view org.eclipse.swt.gtk.linux.x86/src/org/eclipse/swt/internal/image/JPEGDecoder.d @ 113:fb3aa8075988

D2 support for the linux port.
author Jacob Carlborg <doob@me.com>
date Wed, 06 Apr 2011 21:57:23 +0200
parents c01d033c633a
children 536e43f63c81
line wrap: on
line source

/*******************************************************************************
 * Copyright (c) 2000, 2006 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module org.eclipse.swt.internal.image.JPEGDecoder;

import org.eclipse.swt.SWT;
import java.io.InputStream;
import org.eclipse.swt.internal.image.LEDataInputStream;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.graphics.ImageLoader;
import org.eclipse.swt.graphics.ImageLoaderEvent;
import org.eclipse.swt.graphics.PaletteData;
import org.eclipse.swt.graphics.RGB;
import java.lang.all;

version(Tango){
    import tango.util.Convert;
} else { // Phobos
    import std.conv;
}

public class JPEGDecoder {

    static const int DCTSIZE = 8;
    static const int DCTSIZE2 = 64;
    static const int NUM_QUANT_TBLS = 4;
    static const int NUM_HUFF_TBLS = 4;
    static const int NUM_ARITH_TBLS = 16;
    static const int MAX_COMPS_IN_SCAN = 4;
    static const int MAX_COMPONENTS = 10;
    static const int MAX_SAMP_FACTOR = 4;
    static const int D_MAX_BLOCKS_IN_MCU = 10;
    static const int HUFF_LOOKAHEAD = 8;
    static const int MAX_Q_COMPS = 4;
    static const int IFAST_SCALE_BITS = 2;
    static const int MAXJSAMPLE = 255;
    static const int CENTERJSAMPLE = 128;
    static const int MIN_GET_BITS = 32-7;
    static const int INPUT_BUFFER_SIZE = 4096;

    static const int SCALEBITS = 16;    /* speediest right-shift on some machines */
    static const int ONE_HALF = 1 << (SCALEBITS-1);

    static const int RGB_RED = 2;   /* Offset of Red in an RGB scanline element */
    static const int RGB_GREEN = 1; /* Offset of Green */
    static const int RGB_BLUE = 0;  /* Offset of Blue */
    static const int RGB_PIXELSIZE = 3;

    static const int JBUF_PASS_THRU = 0;
    static const int JBUF_SAVE_SOURCE = 1;  /* Run source subobject only, save output */
    static const int JBUF_CRANK_DEST = 2;   /* Run dest subobject only, using saved data */
    static const int JBUF_SAVE_AND_PASS = 3;

    static const int JPEG_MAX_DIMENSION = 65500;
    static const int BITS_IN_JSAMPLE = 8;

    static const int JDITHER_NONE = 0;      /* no dithering */
    static const int JDITHER_ORDERED = 1;   /* simple ordered dither */
    static const int JDITHER_FS = 2;

    static const int JDCT_ISLOW = 0;    /* slow but accurate integer algorithm */
    static const int JDCT_IFAST = 1;    /* faster, less accurate integer method */
    static const int JDCT_FLOAT = 2;    /* floating-point: accurate, fast on fast HW */
    static const int JDCT_DEFAULT = JDCT_ISLOW;

    static const int JCS_UNKNOWN = 0;       /* error/unspecified */
    static const int JCS_GRAYSCALE = 1;     /* monochrome */
    static const int JCS_RGB = 2;       /* red/green/blue */
    static const int JCS_YCbCr = 3;     /* Y/Cb/Cr (also known as YUV) */
    static const int JCS_CMYK = 4;      /* C/M/Y/K */
    static const int JCS_YCCK = 5;      /* Y/Cb/Cr/K */

    static const int SAVED_COEFS = 6;
    static const int Q01_POS = 1;
    static const int Q10_POS = 8;
    static const int Q20_POS = 16;
    static const int Q11_POS = 9;
    static const int Q02_POS = 2;

    static const int CTX_PREPARE_FOR_IMCU = 0;  /* need to prepare for MCU row */
    static const int CTX_PROCESS_IMCU = 1;  /* feeding iMCU to postprocessor */
    static const int CTX_POSTPONED_ROW = 2; /* feeding postponed row group */

    static const int APP0_DATA_LEN = 14;    /* Length of interesting data in APP0 */
    static const int APP14_DATA_LEN = 12;   /* Length of interesting data in APP14 */
    static const int APPN_DATA_LEN = 14;    /* Must be the largest of the above!! */

    /* markers */
    static const int M_SOF0 = 0xc0;
    static const int M_SOF1 = 0xc1;
    static const int M_SOF2 = 0xc2;
    static const int M_SOF3 = 0xc3;
    static const int M_SOF5 = 0xc5;
    static const int M_SOF6 = 0xc6;
    static const int M_SOF7 = 0xc7;
    static const int M_JPG = 0xc8;
    static const int M_SOF9 = 0xc9;
    static const int M_SOF10 = 0xca;
    static const int M_SOF11 = 0xcb;
    static const int M_SOF13 = 0xcd;
    static const int M_SOF14 = 0xce;
    static const int M_SOF15 = 0xcf;
    static const int M_DHT = 0xc4;
    static const int M_DAC = 0xcc;
    static const int M_RST0 = 0xd0;
    static const int M_RST1 = 0xd1;
    static const int M_RST2 = 0xd2;
    static const int M_RST3 = 0xd3;
    static const int M_RST4 = 0xd4;
    static const int M_RST5 = 0xd5;
    static const int M_RST6 = 0xd6;
    static const int M_RST7 = 0xd7;
    static const int M_SOI = 0xd8;
    static const int M_EOI = 0xd9;
    static const int M_SOS = 0xda;
    static const int M_DQT = 0xdb;
    static const int M_DNL = 0xdc;
    static const int M_DRI = 0xdd;
    static const int M_DHP = 0xde;
    static const int M_EXP = 0xdf;
    static const int M_APP0 = 0xe0;
    static const int M_APP1 = 0xe1;
    static const int M_APP2 = 0xe2;
    static const int M_APP3 = 0xe3;
    static const int M_APP4 = 0xe4;
    static const int M_APP5 = 0xe5;
    static const int M_APP6 = 0xe6;
    static const int M_APP7 = 0xe7;
    static const int M_APP8 = 0xe8;
    static const int M_APP9 = 0xe9;
    static const int M_APP10 = 0xea;
    static const int M_APP11 = 0xeb;
    static const int M_APP12 = 0xec;
    static const int M_APP13 = 0xed;
    static const int M_APP14 = 0xee;
    static const int M_APP15 = 0xef;
    static const int M_JPG0 = 0xf0;
    static const int M_JPG13 = 0xfd;
    static const int M_COM = 0xfe;
    static const int M_TEM = 0x01;
    static const int M_ERROR = 0x100;

    /* Values of global_state field (jdapi.c has some dependencies on ordering!) */
    static const int CSTATE_START = 100;    /* after create_compress */
    static const int CSTATE_SCANNING = 101; /* start_compress done, write_scanlines OK */
    static const int CSTATE_RAW_OK = 102;   /* start_compress done, write_raw_data OK */
    static const int CSTATE_WRCOEFS = 103;  /* jpeg_write_coefficients done */
    static const int DSTATE_START = 200;    /* after create_decompress */
    static const int DSTATE_INHEADER = 201; /* reading header markers, no SOS yet */
    static const int DSTATE_READY = 202;    /* found SOS, ready for start_decompress */
    static const int DSTATE_PRELOAD = 203;  /* reading multiscan file in start_decompress*/
    static const int DSTATE_PRESCAN = 204;  /* performing dummy pass for 2-pass quant */
    static const int DSTATE_SCANNING = 205; /* start_decompress done, read_scanlines OK */
    static const int DSTATE_RAW_OK = 206;   /* start_decompress done, read_raw_data OK */
    static const int DSTATE_BUFIMAGE = 207; /* expecting jpeg_start_output */
    static const int DSTATE_BUFPOST = 208;  /* looking for SOS/EOI in jpeg_finish_output */
    static const int DSTATE_RDCOEFS = 209;  /* reading file in jpeg_read_coefficients */
    static const int DSTATE_STOPPING = 210; /* looking for EOI in jpeg_finish_decompress */

    static const int JPEG_REACHED_SOS = 1; /* Reached start of new scan */
    static const int JPEG_REACHED_EOI = 2; /* Reached end of image */
    static const int JPEG_ROW_COMPLETED = 3; /* Completed one iMCU row */
    static const int JPEG_SCAN_COMPLETED = 4; /* Completed last iMCU row of a scan */

    static const int JPEG_SUSPENDED = 0; /* Suspended due to lack of input data */
    static const int JPEG_HEADER_OK = 1; /* Found valid image datastream */
    static const int JPEG_HEADER_TABLES_ONLY = 2; /* Found valid table-specs-only datastream */

    /* Function pointers */
    static const int DECOMPRESS_DATA = 0;
    static const int DECOMPRESS_SMOOTH_DATA = 1;
    static const int DECOMPRESS_ONEPASS = 2;

    static const int CONSUME_DATA = 0;
    static const int DUMMY_CONSUME_DATA = 1;

    static const int PROCESS_DATA_SIMPLE_MAIN = 0;
    static const int PROCESS_DATA_CONTEXT_MAIN = 1;
    static const int PROCESS_DATA_CRANK_POST = 2;

    static const int POST_PROCESS_1PASS = 0;
    static const int POST_PROCESS_DATA_UPSAMPLE = 1;

    static const int NULL_CONVERT = 0;
    static const int GRAYSCALE_CONVERT = 1;
    static const int YCC_RGB_CONVERT = 2;
    static const int GRAY_RGB_CONVERT = 3;
    static const int YCCK_CMYK_CONVERT = 4;

    static const int NOOP_UPSAMPLE = 0;
    static const int FULLSIZE_UPSAMPLE = 1;
    static const int H2V1_FANCY_UPSAMPLE = 2;
    static const int H2V1_UPSAMPLE = 3;
    static const int H2V2_FANCY_UPSAMPLE = 4;
    static const int H2V2_UPSAMPLE = 5;
    static const int INT_UPSAMPLE = 6;

    static const int INPUT_CONSUME_INPUT = 0;
    static const int COEF_CONSUME_INPUT = 1;

    static int extend_test[] =   /* entry n is 2**(n-1) */
    [
        0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
        0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000
    ];

    static int extend_offset[] = /* entry n is (-1 << n) + 1 */
    [
        0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1,
        ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1,
        ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1,
        ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1
    ];

    static int jpeg_natural_order[] = [
        0,  1,  8, 16,  9,  2,  3, 10,
        17, 24, 32, 25, 18, 11, 4,  5,
        12, 19, 26, 33, 40, 48, 41, 34,
        27, 20, 13, 6,  7, 14, 21, 28,
        35, 42, 49, 56, 57, 50, 43, 36,
        29, 22, 15, 23, 30, 37, 44, 51,
        58, 59, 52, 45, 38, 31, 39, 46,
        53, 60, 61, 54, 47, 55, 62, 63,
        63, 63, 63, 63, 63, 63, 63, 63, /* extra entries for safety in decoder */
        63, 63, 63, 63, 63, 63, 63, 63
    ];

    static final class JQUANT_TBL {
        /* This array gives the coefficient quantizers in natural array order
         * (not the zigzag order in which they are stored in a JPEG DQT marker).
         * CAUTION: IJG versions prior to v6a kept this array in zigzag order.
         */
        short[DCTSIZE2] quantval;// = new short[DCTSIZE2];  /* quantization step for each coefficient */
        /* This field is used only during compression.  It's initialized false when
         * the table is created, and set true when it's been output to the file.
         * You could suppress output of a table by setting this to true.
         * (See jpeg_suppress_tables for an example.)
         */
        bool sent_table;     /* true when table has been output */
    }

    static final class JHUFF_TBL {
        /* These two fields directly represent the contents of a JPEG DHT marker */
        byte[17] bits;// = new byte[17]; /* bits[k] = # of symbols with codes of */
                                    /* length k bits; bits[0] is unused */
        byte[256] huffval;// = new byte[256];       /* The symbols, in order of incr code length */
        /* This field is used only during compression.  It's initialized false when
         * the table is created, and set true when it's been output to the file.
         * You could suppress output of a table by setting this to true.
         * (See jpeg_suppress_tables for an example.)
         */
        bool sent_table;     /* true when table has been output */
    }

    static final class bitread_perm_state {     /* Bitreading state saved across MCUs */
        int get_buffer; /* current bit-extraction buffer */
        int bits_left;      /* # of unused bits in it */
    }

    static final class bitread_working_state {      /* Bitreading working state within an MCU */
        /* Current data source location */
        /* We need a copy, rather than munging the original, in case of suspension */
        byte[] buffer; /* => next byte to read from source */
        int bytes_offset;
        int bytes_in_buffer;    /* # of bytes remaining in source buffer */
        /* Bit input buffer --- note these values are kept in register variables,
         * not in this struct, inside the inner loops.
         */
        int get_buffer; /* current bit-extraction buffer */
        int bits_left;      /* # of unused bits in it */
        /* Pointer needed by jpeg_fill_bit_buffer. */
        jpeg_decompress_struct cinfo;   /* back link to decompress master record */
    }

    static final class savable_state {
        int EOBRUN; //Note that this is only used in the progressive case
        int[MAX_COMPS_IN_SCAN] last_dc_val;// = new int[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
    }

    static final class d_derived_tbl {
        /* Basic tables: (element [0] of each array is unused) */
        int[18] maxcode;// = new int[18];       /* largest code of length k (-1 if none) */
        /* (maxcode[17] is a sentinel to ensure jpeg_huff_decode terminates) */
        int[17] valoffset;// = new int[17];     /* huffval[] offset for codes of length k */
        /* valoffset[k] = huffval[] index of 1st symbol of code length k, less
         * the smallest code of length k; so given a code of length k, the
         * corresponding symbol is huffval[code + valoffset[k]]
         */

        /* Link to public Huffman table (needed only in jpeg_huff_decode) */
        JHUFF_TBL pub;

        /* Lookahead tables: indexed by the next HUFF_LOOKAHEAD bits of
         * the input data stream.   If the next Huffman code is no more
         * than HUFF_LOOKAHEAD bits long, we can obtain its length and
         * the corresponding symbol directly from these tables.
         */
        int[1<<HUFF_LOOKAHEAD] look_nbits;// = new int[1<<HUFF_LOOKAHEAD]; /* # bits, or 0 if too long */
        byte[1<<HUFF_LOOKAHEAD] look_sym;// = new byte[1<<HUFF_LOOKAHEAD]; /* symbol, or unused */
    }

    static final class jpeg_d_coef_controller {
        int consume_data;
        int decompress_data;

        /* Pointer to array of coefficient virtual arrays, or null if none */
        short[][][] coef_arrays;

        /* These variables keep track of the current location of the input side. */
        /* cinfo.input_iMCU_row is also used for this. */
        int MCU_ctr;        /* counts MCUs processed in current row */
        int MCU_vert_offset;        /* counts MCU rows within iMCU row */
        int MCU_rows_per_iMCU_row;  /* number of such rows needed */

        /* The output side's location is represented by cinfo.output_iMCU_row. */

        /* In single-pass modes, it's sufficient to buffer just one MCU.
         * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks,
         * and let the entropy decoder write into that workspace each time.
         * (On 80x86, the workspace is FAR even though it's not really very big;
         * this is to keep the module interfaces unchanged when a large coefficient
         * buffer is necessary.)
         * In multi-pass modes, this array points to the current MCU's blocks
         * within the virtual arrays; it is used only by the input side.
         */
        short[][D_MAX_BLOCKS_IN_MCU] MCU_buffer;// = new short[D_MAX_BLOCKS_IN_MCU][];

        /* In multi-pass modes, we need a virtual block array for each component. */
        short[][][][MAX_COMPONENTS] whole_image;// = new short[MAX_COMPONENTS][][][];

        /* When doing block smoothing, we latch coefficient Al values here */
        int[] coef_bits_latch;

        short[] workspace;

        void start_input_pass (jpeg_decompress_struct cinfo) {
            cinfo.input_iMCU_row = 0;
            start_iMCU_row(cinfo);
        }

        /* Reset within-iMCU-row counters for a new row (input side) */
        void start_iMCU_row (jpeg_decompress_struct cinfo) {
            jpeg_d_coef_controller coef = cinfo.coef;

            /* In an interleaved scan, an MCU row is the same as an iMCU row.
             * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
             * But at the bottom of the image, process only what's left.
             */
            if (cinfo.comps_in_scan > 1) {
                coef.MCU_rows_per_iMCU_row = 1;
            } else {
                if (cinfo.input_iMCU_row < (cinfo.total_iMCU_rows-1))
                    coef.MCU_rows_per_iMCU_row = cinfo.cur_comp_info[0].v_samp_factor;
                else
                    coef.MCU_rows_per_iMCU_row = cinfo.cur_comp_info[0].last_row_height;
            }

            coef.MCU_ctr = 0;
            coef.MCU_vert_offset = 0;
        }

    }

    static abstract class jpeg_entropy_decoder {
        abstract void start_pass (jpeg_decompress_struct cinfo);
        abstract bool decode_mcu (jpeg_decompress_struct cinfo, short[][] MCU_data);

        /* This is here to share code between baseline and progressive decoders; */
        /* other modules probably should not use it */
        bool insufficient_data;  /* set true after emitting warning */

        bitread_working_state br_state_local;
        savable_state state_local;
        public this(){
            br_state_local = new bitread_working_state();
            state_local = new savable_state();
        }
    }

    static final class huff_entropy_decoder : jpeg_entropy_decoder {
        bitread_perm_state bitstate;// = new bitread_perm_state();  /* Bit buffer at start of MCU */
        savable_state saved;// = new savable_state();       /* Other state at start of MCU */

        /* These fields are NOT loaded into local working state. */
        int restarts_to_go; /* MCUs left in this restart interval */

        /* Pointers to derived tables (these workspaces have image lifespan) */
        d_derived_tbl[NUM_HUFF_TBLS] dc_derived_tbls;// = new d_derived_tbl[NUM_HUFF_TBLS];
        d_derived_tbl[NUM_HUFF_TBLS] ac_derived_tbls;// = new d_derived_tbl[NUM_HUFF_TBLS];

        /* Precalculated info set up by start_pass for use in decode_mcu: */

        /* Pointers to derived tables to be used for each block within an MCU */
        d_derived_tbl[D_MAX_BLOCKS_IN_MCU] dc_cur_tbls;// = new d_derived_tbl[D_MAX_BLOCKS_IN_MCU];
        d_derived_tbl[D_MAX_BLOCKS_IN_MCU] ac_cur_tbls;// = new d_derived_tbl[D_MAX_BLOCKS_IN_MCU];
        /* Whether we care about the DC and AC coefficient values for each block */
        bool[D_MAX_BLOCKS_IN_MCU] dc_needed;// = new bool[D_MAX_BLOCKS_IN_MCU];
        bool[D_MAX_BLOCKS_IN_MCU] ac_needed;// = new bool[D_MAX_BLOCKS_IN_MCU];

        public this(){
            bitstate = new bitread_perm_state(); /* Bit buffer at start of MCU */
            saved = new savable_state();      /* Other state at start of MCU */
        }

        override void start_pass (jpeg_decompress_struct cinfo) {
            start_pass_huff_decoder(cinfo);
        }

        override bool decode_mcu (jpeg_decompress_struct cinfo, short[][] MCU_data) {
            huff_entropy_decoder entropy = this;
            int blkn;
//          BITREAD_STATE_VARS;
            int get_buffer;
            int bits_left;
//          bitread_working_state br_state = new bitread_working_state();
//          savable_state state = new savable_state();
            bitread_working_state br_state = br_state_local;
            savable_state state = state_local;

                /* Process restart marker if needed; may have to suspend */
            if (cinfo.restart_interval !is 0) {
                if (entropy.restarts_to_go is 0)
                    if (! process_restart(cinfo))
                        return false;
            }

            /* If we've run out of data, just leave the MCU set to zeroes.
             * This way, we return uniform gray for the remainder of the segment.
             */
            if (! entropy.insufficient_data) {

                /* Load up working state */
//              BITREAD_LOAD_STATE(cinfo,entropy.bitstate);
                br_state.cinfo = cinfo;
                br_state.buffer = cinfo.buffer;
                br_state.bytes_in_buffer = cinfo.bytes_in_buffer;
                br_state.bytes_offset = cinfo.bytes_offset;
                get_buffer = entropy.bitstate.get_buffer;
                bits_left = entropy.bitstate.bits_left;

//              ASSIGN_STATE(state, entropy.saved);
                state.last_dc_val[0] = entropy.saved.last_dc_val[0];
                state.last_dc_val[1] = entropy.saved.last_dc_val[1];
                state.last_dc_val[2] = entropy.saved.last_dc_val[2];
                state.last_dc_val[3] = entropy.saved.last_dc_val[3];

                /* Outer loop handles each block in the MCU */

                for (blkn = 0; blkn < cinfo.blocks_in_MCU; blkn++) {
                    short[] block = MCU_data[blkn];
                    d_derived_tbl dctbl = entropy.dc_cur_tbls[blkn];
                    d_derived_tbl actbl = entropy.ac_cur_tbls[blkn];
                    int s = 0, k, r;

                    /* Decode a single block's worth of coefficients */

                    /* Section F.2.2.1: decode the DC coefficient difference */
//                  HUFF_DECODE(s, br_state, dctbl, return FALSE, label1);
                    {
                    int nb = 0, look;
                    if (bits_left < HUFF_LOOKAHEAD) {
                        if (!jpeg_fill_bit_buffer(br_state,get_buffer,bits_left, 0)) {
                            return false;
                        }
                        get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                        if (bits_left < HUFF_LOOKAHEAD) {
                            nb = 1;
//                          goto slowlabel;
                            if ((s=jpeg_huff_decode(br_state,get_buffer,bits_left,dctbl,nb)) < 0) {
                                return false;
                            }
                            get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                        }
                    }
//                  look = PEEK_BITS(HUFF_LOOKAHEAD);
                    if (nb !is 1) {
                        look = (( (get_buffer >> (bits_left -   (HUFF_LOOKAHEAD)))) & ((1<<(HUFF_LOOKAHEAD))-1));
                        if ((nb = dctbl.look_nbits[look]) !is 0) {
//                          DROP_BITS(nb);
                            bits_left -= nb;
                            s = dctbl.look_sym[look] & 0xFF;
                        } else {
                            nb = HUFF_LOOKAHEAD+1;
//                          slowlabel:
                            if ((s=jpeg_huff_decode(br_state,get_buffer,bits_left,dctbl,nb)) < 0) {
                                return false;
                            }
                            get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                        }
                    }
                    }

                    if (s !is 0) {
//                      CHECK_BIT_BUFFER(br_state, s, return FALSE);
                        {
                        if (bits_left < (s)) {
                            if (!jpeg_fill_bit_buffer(br_state,get_buffer,bits_left,s)) {
                                return false;
                            }
                            get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                        }
                        }
//                      r = GET_BITS(s);
                        r = (( (get_buffer >> (bits_left -= (s)))) & ((1<<(s))-1));
//                      s = HUFF_EXTEND(r, s);
                        s = ((r) < extend_test[s] ? (r) + extend_offset[s] : (r));
                    }

                    if (entropy.dc_needed[blkn]) {
                        /* Convert DC difference to actual value, update last_dc_val */
                        int ci = cinfo.MCU_membership[blkn];
                        s += state.last_dc_val[ci];
                        state.last_dc_val[ci] = s;
                        /* Output the DC coefficient (assumes jpeg_natural_order[0] = 0) */
                        block[0] = cast(short) s;
                    }

                    if (entropy.ac_needed[blkn]) {

                        /* Section F.2.2.2: decode the AC coefficients */
                        /* Since zeroes are skipped, output area must be cleared beforehand */
                        for (k = 1; k < DCTSIZE2; k++) {
//                          HUFF_DECODE(s, br_state, actbl, return FALSE, label2);
                            {
                            int nb = 0, look;
                            if (bits_left < HUFF_LOOKAHEAD) {
                                if (!jpeg_fill_bit_buffer(br_state,get_buffer,bits_left, 0)) {
                                    return false;
                                }
                                get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                                if (bits_left < HUFF_LOOKAHEAD) {
                                    nb = 1;
//                                  goto slowlabel;
                                    if ((s=jpeg_huff_decode(br_state,get_buffer,bits_left,actbl,nb)) < 0) {
                                        return false;
                                    }
                                    get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                                }
                            }
                            if (nb !is 1) {
//                              look = PEEK_BITS(HUFF_LOOKAHEAD);
                                look = (( (get_buffer >> (bits_left -   (HUFF_LOOKAHEAD)))) & ((1<<(HUFF_LOOKAHEAD))-1));
                                if ((nb = actbl.look_nbits[look]) !is 0) {
//                                  DROP_BITS(nb);
                                    bits_left -= (nb);
                                    s = actbl.look_sym[look] & 0xFF;
                                } else {
                                    nb = HUFF_LOOKAHEAD+1;
//                                  slowlabel:
                                    if ((s=jpeg_huff_decode(br_state,get_buffer,bits_left,actbl,nb)) < 0) {
                                        return false;
                                    }
                                    get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                                }
                            }
                            }
                            r = s >> 4;
                            s &= 15;

                            if (s !is 0) {
                                k += r;
//                              CHECK_BIT_BUFFER(br_state, s, return FALSE);
                                {
                                if (bits_left < (s)) {
                                    if (!jpeg_fill_bit_buffer(br_state, get_buffer, bits_left, s)) {
                                        return false;
                                    }
                                    get_buffer = br_state.get_buffer;
                                    bits_left = br_state.bits_left;
                                }
                                }
//                              r = GET_BITS(s);
                                r = (((get_buffer >> (bits_left -= (s)))) & ((1 << (s)) - 1));
//                              s = HUFF_EXTEND(r, s);
                                s = ((r) < extend_test[s] ? (r) + extend_offset[s] : (r));
                                /*
                                 * Output coefficient in natural (dezigzagged)
                                 * order. Note: the extra entries in
                                 * jpeg_natural_order[] will save us if k >=
                                 * DCTSIZE2, which could happen if the data is
                                 * corrupted.
                                 */
                                block[jpeg_natural_order[k]] = cast(short) s;
                            } else {
                                if (r !is 15)
                                    break;
                                k += 15;
                            }
                        }

                    } else {

                        /* Section F.2.2.2: decode the AC coefficients */
                        /* In this path we just discard the values */
                        for (k = 1; k < DCTSIZE2; k++) {
//                          HUFF_DECODE(s, br_state, actbl, return FALSE, label3);
                            {
                            int nb = 0, look;
                            if (bits_left < HUFF_LOOKAHEAD) {
                                if (!jpeg_fill_bit_buffer(br_state,get_buffer,bits_left, 0)) {
                                    return false;
                                }
                                get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                                if (bits_left < HUFF_LOOKAHEAD) {
                                    nb = 1;
//                                  goto slowlabel;
                                    if ((s=jpeg_huff_decode(br_state,get_buffer,bits_left,actbl,nb)) < 0) {
                                        return false;
                                    }
                                    get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                                }
                            }
                            if (nb !is 1) {
//                              look = PEEK_BITS(HUFF_LOOKAHEAD);
                                look = (( (get_buffer >> (bits_left -   (HUFF_LOOKAHEAD)))) & ((1<<(HUFF_LOOKAHEAD))-1));
                                if ((nb = actbl.look_nbits[look]) !is 0) {
//                                  DROP_BITS(nb);
                                    bits_left -= (nb);
                                    s = actbl.look_sym[look] & 0xFF;
                                } else {
                                    nb = HUFF_LOOKAHEAD+1;
//                                  slowlabel:
                                    if ((s=jpeg_huff_decode(br_state,get_buffer,bits_left,actbl,nb)) < 0) {
                                        return false;
                                    }
                                    get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                                }
                            }
                            }
                            r = s >> 4;
                            s &= 15;

                            if (s !is 0) {
                                k += r;
//                              CHECK_BIT_BUFFER(br_state, s, return FALSE);
                                {
                                if (bits_left < (s)) {
                                    if (!jpeg_fill_bit_buffer(br_state,get_buffer,bits_left,s)) {
                                        return false;
                                    }
                                    get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                                    }
                                }
//                              DROP_BITS(s);
                                bits_left -= s;
                            } else {
                                if (r !is 15)
                                    break;
                                k += 15;
                            }
                        }

                    }
                }

                /* Completed MCU, so update state */
//              BITREAD_SAVE_STATE(cinfo,entropy.bitstate);
                cinfo.buffer = br_state.buffer;
                cinfo.bytes_in_buffer = br_state.bytes_in_buffer;
                cinfo.bytes_offset = br_state.bytes_offset;
                entropy.bitstate.get_buffer = get_buffer;
                entropy.bitstate.bits_left = bits_left;
//              ASSIGN_STATE(entropy.saved, state);
                entropy.saved.last_dc_val[0] = state.last_dc_val[0];
                entropy.saved.last_dc_val[1] = state.last_dc_val[1];
                entropy.saved.last_dc_val[2] = state.last_dc_val[2];
                entropy.saved.last_dc_val[3] = state.last_dc_val[3];
            }

            /* Account for restart interval (no-op if not using restarts) */
            entropy.restarts_to_go--;

            return true;
        }

        void start_pass_huff_decoder (jpeg_decompress_struct cinfo) {
            huff_entropy_decoder entropy = this;
            int ci, blkn, dctbl, actbl;
            jpeg_component_info compptr;

            /* Check that the scan parameters Ss, Se, Ah/Al are OK for sequential JPEG.
             * This ought to be an error condition, but we make it a warning because
             * there are some baseline files out there with all zeroes in these bytes.
             */
            if (cinfo.Ss !is 0 || cinfo.Se !is DCTSIZE2-1 || cinfo.Ah !is 0 || cinfo.Al !is 0) {
//              WARNMS(cinfo, JWRN_NOT_SEQUENTIAL);
            }

            for (ci = 0; ci < cinfo.comps_in_scan; ci++) {
                compptr = cinfo.cur_comp_info[ci];
                dctbl = compptr.dc_tbl_no;
                actbl = compptr.ac_tbl_no;
                /* Compute derived values for Huffman tables */
                /* We may do this more than once for a table, but it's not expensive */
                jpeg_make_d_derived_tbl(cinfo, true, dctbl, entropy.dc_derived_tbls[dctbl] = new d_derived_tbl());
                jpeg_make_d_derived_tbl(cinfo, false, actbl, entropy.ac_derived_tbls[actbl] = new d_derived_tbl());
                /* Initialize DC predictions to 0 */
                entropy.saved.last_dc_val[ci] = 0;
            }

            /* Precalculate decoding info for each block in an MCU of this scan */
            for (blkn = 0; blkn < cinfo.blocks_in_MCU; blkn++) {
                ci = cinfo.MCU_membership[blkn];
                compptr = cinfo.cur_comp_info[ci];
                /* Precalculate which table to use for each block */
                entropy.dc_cur_tbls[blkn] = entropy.dc_derived_tbls[compptr.dc_tbl_no];
                entropy.ac_cur_tbls[blkn] = entropy.ac_derived_tbls[compptr.ac_tbl_no];
                /* Decide whether we really care about the coefficient values */
                if (compptr.component_needed) {
                    entropy.dc_needed[blkn] = true;
                    /* we don't need the ACs if producing a 1/8th-size image */
                    entropy.ac_needed[blkn] = (compptr.DCT_scaled_size > 1);
                } else {
                    entropy.dc_needed[blkn] = entropy.ac_needed[blkn] = false;
                }
            }

            /* Initialize bitread state variables */
            entropy.bitstate.bits_left = 0;
            entropy.bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
            entropy.insufficient_data = false;

            /* Initialize restart counter */
            entropy.restarts_to_go = cinfo.restart_interval;
        }

        bool process_restart (jpeg_decompress_struct cinfo) {
            huff_entropy_decoder entropy = this;
            int ci;

            /* Throw away any unused bits remaining in bit buffer; */
            /* include any full bytes in next_marker's count of discarded bytes */
            cinfo.marker.discarded_bytes += entropy.bitstate.bits_left / 8;
            entropy.bitstate.bits_left = 0;

            /* Advance past the RSTn marker */
            if (! read_restart_marker (cinfo))
                return false;

            /* Re-initialize DC predictions to 0 */
            for (ci = 0; ci < cinfo.comps_in_scan; ci++)
                entropy.saved.last_dc_val[ci] = 0;

            /* Reset restart counter */
            entropy.restarts_to_go = cinfo.restart_interval;

            /* Reset out-of-data flag, unless read_restart_marker left us smack up
             * against a marker.    In that case we will end up treating the next data
             * segment as empty, and we can avoid producing bogus output pixels by
             * leaving the flag set.
             */
            if (cinfo.unread_marker is 0)
                entropy.insufficient_data = false;

            return true;
        }
    }

    static final class phuff_entropy_decoder : jpeg_entropy_decoder {

        /* These fields are loaded into local variables at start of each MCU.
         * In case of suspension, we exit WITHOUT updating them.
         */
        bitread_perm_state bitstate;// = new bitread_perm_state();  /* Bit buffer at start of MCU */
        savable_state saved;// = new savable_state();       /* Other state at start of MCU */

        /* These fields are NOT loaded into local working state. */
        int restarts_to_go; /* MCUs left in this restart interval */

        /* Pointers to derived tables (these workspaces have image lifespan) */
        d_derived_tbl[NUM_HUFF_TBLS] derived_tbls;// = new d_derived_tbl[NUM_HUFF_TBLS];

        d_derived_tbl ac_derived_tbl; /* active table during an AC scan */

        int[DCTSIZE2] newnz_pos;// = new int[DCTSIZE2];

        public this(){
            bitstate = new bitread_perm_state(); /* Bit buffer at start of MCU */
            saved = new savable_state();      /* Other state at start of MCU */
        }

        override void start_pass (jpeg_decompress_struct cinfo) {
            start_pass_phuff_decoder(cinfo);
        }

        override bool decode_mcu (jpeg_decompress_struct cinfo, short[][] MCU_data) {
            bool is_DC_band = (cinfo.Ss is 0);
            if (cinfo.Ah is 0) {
                if (is_DC_band)
                    return decode_mcu_DC_first(cinfo, MCU_data);
                else
                    return decode_mcu_AC_first(cinfo, MCU_data);
            } else {
                if (is_DC_band)
                    return decode_mcu_DC_refine(cinfo, MCU_data);
                else
                    return decode_mcu_AC_refine(cinfo, MCU_data);
            }
        }

        bool decode_mcu_DC_refine (jpeg_decompress_struct cinfo, short[][] MCU_data) {
            phuff_entropy_decoder entropy = this;
            int p1 = 1 << cinfo.Al; /* 1 in the bit position being coded */
            int blkn;
            short[] block;
//          BITREAD_STATE_VARS;
            int get_buffer;
            int bits_left;
//          bitread_working_state br_state = new bitread_working_state();
            bitread_working_state br_state = br_state_local;

            /* Process restart marker if needed; may have to suspend */
            if (cinfo.restart_interval !is 0) {
                if (entropy.restarts_to_go is 0)
                    if (! process_restart(cinfo))
                        return false;
            }

            /* Not worth the cycles to check insufficient_data here,
             * since we will not change the data anyway if we read zeroes.
             */

            /* Load up working state */
//          BITREAD_LOAD_STATE(cinfo,entropy.bitstate);
            br_state.cinfo = cinfo;
            br_state.buffer = cinfo.buffer;
            br_state.bytes_in_buffer = cinfo.bytes_in_buffer;
            br_state.bytes_offset = cinfo.bytes_offset;
            get_buffer = entropy.bitstate.get_buffer;
            bits_left = entropy.bitstate.bits_left;

            /* Outer loop handles each block in the MCU */

            for (blkn = 0; blkn < cinfo.blocks_in_MCU; blkn++) {
                block = MCU_data[blkn];

                /* Encoded data is simply the next bit of the two's-complement DC value */
//              CHECK_BIT_BUFFER(br_state, 1, return FALSE);
                {
                if (bits_left < (1)) {
                    if (!jpeg_fill_bit_buffer(br_state,get_buffer,bits_left,1)) {
                         return false;
                    }
                    get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                }
                }
//              if (GET_BITS(1))
                if ((( (get_buffer >> (bits_left -= (1)))) & ((1<<(1))-1)) !is 0)
                    block[0] |= p1;
                    /* Note: since we use |=, repeating the assignment later is safe */
            }

            /* Completed MCU, so update state */
//          BITREAD_SAVE_STATE(cinfo,entropy.bitstate);
            cinfo.buffer = br_state.buffer;
            cinfo.bytes_in_buffer = br_state.bytes_in_buffer;
            cinfo.bytes_offset = br_state.bytes_offset;
            entropy.bitstate.get_buffer = get_buffer;
            entropy.bitstate.bits_left = bits_left;

            /* Account for restart interval (no-op if not using restarts) */
            entropy.restarts_to_go--;

            return true;

        }

        bool decode_mcu_AC_refine (jpeg_decompress_struct cinfo, short[][] MCU_data) {
            phuff_entropy_decoder entropy = this;
            int Se = cinfo.Se;
            int p1 = 1 << cinfo.Al; /* 1 in the bit position being coded */
            int m1 = (-1) << cinfo.Al;  /* -1 in the bit position being coded */
            int s = 0, k, r;
            int EOBRUN;
            short[] block;
            short[] thiscoef;
//          BITREAD_STATE_VARS;
            int get_buffer;
            int bits_left;
//          bitread_working_state br_state = new bitread_working_state();
            bitread_working_state br_state = br_state_local;

            d_derived_tbl tbl;
            int num_newnz;
            int[] newnz_pos = entropy.newnz_pos;

                /* Process restart marker if needed; may have to suspend */
            if (cinfo.restart_interval !is 0) {
                if (entropy.restarts_to_go is 0)
                    if (! process_restart(cinfo))
                        return false;
            }

            /* If we've run out of data, don't modify the MCU.
             */
            if (! entropy.insufficient_data) {

                /* Load up working state */
//              BITREAD_LOAD_STATE(cinfo,entropy.bitstate);
                br_state.cinfo = cinfo;
                br_state.buffer = cinfo.buffer;
                br_state.bytes_in_buffer = cinfo.bytes_in_buffer;
                br_state.bytes_offset = cinfo.bytes_offset;
                get_buffer = entropy.bitstate.get_buffer;
                bits_left = entropy.bitstate.bits_left;

                EOBRUN = entropy.saved.EOBRUN; /* only part of saved state we need */

                /* There is always only one block per MCU */
                block = MCU_data[0];
                tbl = entropy.ac_derived_tbl;

                /* If we are forced to suspend, we must undo the assignments to any newly
                 * nonzero coefficients in the block, because otherwise we'd get confused
                 * next time about which coefficients were already nonzero.
                 * But we need not undo addition of bits to already-nonzero coefficients;
                 * instead, we can test the current bit to see if we already did it.
                 */
                num_newnz = 0;

                /* initialize coefficient loop counter to start of band */
                k = cinfo.Ss;

                if (EOBRUN is 0) {
                    for (; k <= Se; k++) {
//                      HUFF_DECODE(s, br_state, tbl, goto undoit, label3);
                        {
                        int nb = 0, look;
                        if (bits_left < HUFF_LOOKAHEAD) {
                            if (! jpeg_fill_bit_buffer(br_state,get_buffer,bits_left, 0)) {
//                              failaction;
                                while (num_newnz > 0)
                                    block[newnz_pos[--num_newnz]] = 0;

                                return false;
                            }
                            get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                            if (bits_left < HUFF_LOOKAHEAD) {
                                nb = 1;
//                              goto slowlabel;
                                if ((s=jpeg_huff_decode(br_state,get_buffer,bits_left,tbl,nb)) < 0) {
//                                  failaction;
                                    while (num_newnz > 0)
                                        block[newnz_pos[--num_newnz]] = 0;

                                    return false;
                                }
                                get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                            }
                        }
                        if (nb !is 1) {
//                          look = PEEK_BITS(HUFF_LOOKAHEAD);
                            look = (( (get_buffer >> (bits_left -   (HUFF_LOOKAHEAD)))) & ((1<<(HUFF_LOOKAHEAD))-1));
                            if ((nb = tbl.look_nbits[look]) !is 0) {
//                              DROP_BITS(nb);
                                bits_left -= nb;
                                s = tbl.look_sym[look] & 0xFF;
                            } else {
                                nb = HUFF_LOOKAHEAD+1;
//                              slowlabel:
                                if ((s=jpeg_huff_decode(br_state,get_buffer,bits_left,tbl,nb)) < 0) {
//                                  failaction;
                                    while (num_newnz > 0)
                                        block[newnz_pos[--num_newnz]] = 0;

                                    return false;
                                }
                                get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                            }
                        }
                        }
                        r = s >> 4;
                        s &= 15;
                        if (s !is 0) {
                            if (s !is 1) {       /* size of new coef should always be 1 */
//                              WARNMS(cinfo, JWRN_HUFF_BAD_CODE);
                            }
//                          CHECK_BIT_BUFFER(br_state, 1, goto undoit);
                            {
                            if (bits_left < (1)) {
                                if (! jpeg_fill_bit_buffer(br_state,get_buffer,bits_left,1)) {
//                                  failaction;
                                    while (num_newnz > 0)
                                        block[newnz_pos[--num_newnz]] = 0;

                                    return false;
                                }
                                get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                                }
                            }
//                          if (GET_BITS(1))
                            if ((( (get_buffer >> (bits_left -= (1)))) & ((1<<(1))-1)) !is 0)
                                s = p1;     /* newly nonzero coef is positive */
                            else
                                s = m1;     /* newly nonzero coef is negative */
                        } else {
                            if (r !is 15) {
                                EOBRUN = 1 << r;    /* EOBr, run length is 2^r + appended bits */
                                if (r !is 0) {
//                                  CHECK_BIT_BUFFER(br_state, r, goto undoit);
                                    {
                                    if (bits_left < (r)) {
                                        if (!jpeg_fill_bit_buffer(br_state,get_buffer,bits_left,r)) {
//                                          failaction;
                                            while (num_newnz > 0)
                                                block[newnz_pos[--num_newnz]] = 0;

                                            return false;
                                        }
                                        get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                                    }
                                    }
//                                  r = GET_BITS(r);
                                    r = (( (get_buffer >> (bits_left -= (r)))) & ((1<<(r))-1));
                                    EOBRUN += r;
                                }
                                break;      /* rest of block is handled by EOB logic */
                            }
                            /* note s = 0 for processing ZRL */
                        }
                        /* Advance over already-nonzero coefs and r still-zero coefs,
                         * appending correction bits to the nonzeroes.  A correction bit is 1
                         * if the absolute value of the coefficient must be increased.
                         */
                        do {
                            thiscoef = block;
                            int thiscoef_offset = jpeg_natural_order[k];
                            if (thiscoef[thiscoef_offset] !is 0) {
//                              CHECK_BIT_BUFFER(br_state, 1, goto undoit);
                                {
                                if (bits_left < (1)) {
                                    if (!jpeg_fill_bit_buffer(br_state,get_buffer,bits_left,1)) {
//                                      failaction;
                                        while (num_newnz > 0)
                                            block[newnz_pos[--num_newnz]] = 0;

                                        return false;
                                    }
                                    get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                                }
                                }
//                              if (GET_BITS(1)) {
                                if ((( (get_buffer >> (bits_left -= (1)))) & ((1<<(1))-1)) !is 0) {
                                    if ((thiscoef[thiscoef_offset] & p1) is 0) { /* do nothing if already set it */
                                        if (thiscoef[thiscoef_offset] >= 0)
                                            thiscoef[thiscoef_offset] += p1;
                                        else
                                            thiscoef[thiscoef_offset] += m1;
                                    }
                                }
                            } else {
                                if (--r < 0)
                                    break;      /* reached target zero coefficient */
                            }
                            k++;
                        } while (k <= Se);
                        if (s !is 0) {
                            int pos = jpeg_natural_order[k];
                            /* Output newly nonzero coefficient */
                            block[pos] = cast(short) s;
                            /* Remember its position in case we have to suspend */
                            newnz_pos[num_newnz++] = pos;
                        }
                    }
                }

                if (EOBRUN > 0) {
                    /* Scan any remaining coefficient positions after the end-of-band
                     * (the last newly nonzero coefficient, if any).    Append a correction
                     * bit to each already-nonzero coefficient. A correction bit is 1
                     * if the absolute value of the coefficient must be increased.
                     */
                    for (; k <= Se; k++) {
                        thiscoef = block;
                        int thiscoef_offset = jpeg_natural_order[k];
                        if (thiscoef[thiscoef_offset] !is 0) {
//                          CHECK_BIT_BUFFER(br_state, 1, goto undoit);
                            {
                            if (bits_left < (1)) {
                                if (! jpeg_fill_bit_buffer(br_state,get_buffer,bits_left,1)) {
//                                  failaction;
                                    while (num_newnz > 0)
                                        block[newnz_pos[--num_newnz]] = 0;

                                    return false;
                                }
                                get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                            }
                            }
//                          if (GET_BITS(1)) {
                            if ((( (get_buffer >> (bits_left -= (1)))) & ((1<<(1))-1)) !is 0) {
                                if ((thiscoef[thiscoef_offset] & p1) is 0) { /* do nothing if already changed it */
                                    if (thiscoef[thiscoef_offset] >= 0)
                                        thiscoef[thiscoef_offset] += p1;
                                    else
                                        thiscoef[thiscoef_offset] += m1;
                                }
                            }
                        }
                    }
                        /* Count one block completed in EOB run */
                    EOBRUN--;
                }

                /* Completed MCU, so update state */
//              BITREAD_SAVE_STATE(cinfo,entropy.bitstate);
                cinfo.buffer = br_state.buffer;
                cinfo.bytes_in_buffer = br_state.bytes_in_buffer;
                cinfo.bytes_offset = br_state.bytes_offset;
                entropy.bitstate.get_buffer = get_buffer;
                entropy.bitstate.bits_left = bits_left;

                entropy.saved.EOBRUN = EOBRUN; /* only part of saved state we need */
            }

            /* Account for restart interval (no-op if not using restarts) */
            entropy.restarts_to_go--;

            return true;

//          undoit:
//              /* Re-zero any output coefficients that we made newly nonzero */
//              while (num_newnz > 0)
//                  (*block)[newnz_pos[--num_newnz]] = 0;
//
//              return false;

        }

        bool decode_mcu_AC_first (jpeg_decompress_struct cinfo, short[][] MCU_data) {
            phuff_entropy_decoder entropy = this;
            int Se = cinfo.Se;
            int Al = cinfo.Al;
            int s = 0, k, r;
            int EOBRUN;
            short[] block;
//          BITREAD_STATE_VARS;
            int get_buffer;
            int bits_left;
//          bitread_working_state br_state = new bitread_working_state();
            bitread_working_state br_state = br_state_local;

            d_derived_tbl tbl;

            /* Process restart marker if needed; may have to suspend */
            if (cinfo.restart_interval !is 0) {
                if (entropy.restarts_to_go is 0)
                    if (! process_restart(cinfo))
                        return false;
            }

            /* If we've run out of data, just leave the MCU set to zeroes.
             * This way, we return uniform gray for the remainder of the segment.
             */
            if (! entropy.insufficient_data) {

                /* Load up working state.
                 * We can avoid loading/saving bitread state if in an EOB run.
                 */
                EOBRUN = entropy.saved.EOBRUN;  /* only part of saved state we need */

                /* There is always only one block per MCU */

                if (EOBRUN > 0)     /* if it's a band of zeroes... */
                    EOBRUN--;           /* ...process it now (we do nothing) */
                else {
//                  BITREAD_LOAD_STATE(cinfo,entropy.bitstate);
                    br_state.cinfo = cinfo;
                    br_state.buffer = cinfo.buffer;
                    br_state.bytes_in_buffer = cinfo.bytes_in_buffer;
                    br_state.bytes_offset = cinfo.bytes_offset;
                    get_buffer = entropy.bitstate.get_buffer;
                    bits_left = entropy.bitstate.bits_left;

                    block = MCU_data[0];
                    tbl = entropy.ac_derived_tbl;

                    for (k = cinfo.Ss; k <= Se; k++) {
//                      HUFF_DECODE(s, br_state, tbl, return FALSE, label2);
                        {
                        int nb = 0, look;
                        if (bits_left < HUFF_LOOKAHEAD) {
                            if (! jpeg_fill_bit_buffer(br_state,get_buffer,bits_left, 0)) {
                                return false;
                            }
                            get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                            if (bits_left < HUFF_LOOKAHEAD) {
                                nb = 1;
//                              goto slowlabel;
                                if ((s=jpeg_huff_decode(br_state,get_buffer,bits_left,tbl,nb)) < 0) {
                                    return false;
                                }
                                get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                            }
                        }
                        if (nb !is 1) {
//                          look = PEEK_BITS(HUFF_LOOKAHEAD);
                            look = (( (get_buffer >> (bits_left -   (HUFF_LOOKAHEAD)))) & ((1<<(HUFF_LOOKAHEAD))-1));

                            if ((nb = tbl.look_nbits[look]) !is 0) {
//                              DROP_BITS(nb);
                                bits_left -= nb;
                                s = tbl.look_sym[look] & 0xFF;
                            } else {
                                nb = HUFF_LOOKAHEAD+1;
//                              slowlabel:
                                if ((s=jpeg_huff_decode(br_state,get_buffer,bits_left,tbl,nb)) < 0) {
                                    return false;
                                }
                                get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                            }
                        }
                        }
                        r = s >> 4;
                        s &= 15;
                        if (s !is 0) {
                            k += r;
//                          CHECK_BIT_BUFFER(br_state, s, return FALSE);
                            {
                            if (bits_left < (s)) {
                                if (! jpeg_fill_bit_buffer(br_state,get_buffer,bits_left,s)) {
                                    return false;
                                }
                                get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                            }
                            }
//                          r = GET_BITS(s);
                            r = (( (get_buffer >> (bits_left -= (s)))) & ((1<<(s))-1));
//                          s = HUFF_EXTEND(r, s);
                            s = ((r) < extend_test[s] ? (r) + extend_offset[s] : (r));
                            /* Scale and output coefficient in natural (dezigzagged) order */
                            block[jpeg_natural_order[k]] = cast(short) (s << Al);
                        } else {
                            if (r is 15) {  /* ZRL */
                                k += 15;        /* skip 15 zeroes in band */
                            } else {        /* EOBr, run length is 2^r + appended bits */
                                EOBRUN = 1 << r;
                                if (r !is 0) {       /* EOBr, r > 0 */
//                                  CHECK_BIT_BUFFER(br_state, r, return FALSE);
                                    {
                                    if (bits_left < (r)) {
                                        if (! jpeg_fill_bit_buffer(br_state,get_buffer,bits_left,r)) {
                                            return false;
                                        }
                                        get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                                    }
                                    }
//                                  r = GET_BITS(r);
                                    r = (( (get_buffer >> (bits_left -= (r)))) & ((1<<(r))-1));
                                    EOBRUN += r;
                                }
                                EOBRUN--;       /* this band is processed at this moment */
                                break;      /* force end-of-band */
                            }
                        }
                    }

//                  BITREAD_SAVE_STATE(cinfo,entropy.bitstate);
                    cinfo.buffer = br_state.buffer;
                    cinfo.bytes_in_buffer = br_state.bytes_in_buffer;
                    cinfo.bytes_offset = br_state.bytes_offset;
                    entropy.bitstate.get_buffer = get_buffer;
                    entropy.bitstate.bits_left = bits_left;
                }

                /* Completed MCU, so update state */
                entropy.saved.EOBRUN = EOBRUN;  /* only part of saved state we need */
            }

            /* Account for restart interval (no-op if not using restarts) */
            entropy.restarts_to_go--;

            return true;
        }

        bool decode_mcu_DC_first (jpeg_decompress_struct cinfo, short[][] MCU_data) {     
            phuff_entropy_decoder entropy = this;
            int Al = cinfo.Al;
            int s = 0, r;
            int blkn, ci;
            short[] block;
//          BITREAD_STATE_VARS;
            int get_buffer;
            int bits_left;
//          bitread_working_state br_state = new bitread_working_state();
            bitread_working_state br_state = br_state_local;

//          savable_state state = new savable_state();
            savable_state state = state_local;
            d_derived_tbl tbl;
            jpeg_component_info compptr;

            /* Process restart marker if needed; may have to suspend */
            if (cinfo.restart_interval !is 0) {
                if (entropy.restarts_to_go is 0)
                    if (! process_restart(cinfo))
                        return false;
            }

            /* If we've run out of data, just leave the MCU set to zeroes.
             * This way, we return uniform gray for the remainder of the segment.
             */
            if (! entropy.insufficient_data) {

                /* Load up working state */
//              BITREAD_LOAD_STATE(cinfo,entropy.bitstate);
                br_state.cinfo = cinfo;
                br_state.buffer = cinfo.buffer;
                br_state.bytes_in_buffer = cinfo.bytes_in_buffer;
                br_state.bytes_offset = cinfo.bytes_offset;
                get_buffer = entropy.bitstate.get_buffer;
                bits_left = entropy.bitstate.bits_left;

//              ASSIGN_STATE(state, entropy.saved);
                state.EOBRUN = entropy.saved.EOBRUN;
                state.last_dc_val[0] = entropy.saved.last_dc_val[0];
                state.last_dc_val[1] = entropy.saved.last_dc_val[1];
                state.last_dc_val[2] = entropy.saved.last_dc_val[2];
                state.last_dc_val[3] = entropy.saved.last_dc_val[3];

                /* Outer loop handles each block in the MCU */

                for (blkn = 0; blkn < cinfo.blocks_in_MCU; blkn++) {
                    block = MCU_data[blkn];
                    ci = cinfo.MCU_membership[blkn];
                    compptr = cinfo.cur_comp_info[ci];
                    tbl = entropy.derived_tbls[compptr.dc_tbl_no];

                    /* Decode a single block's worth of coefficients */

                    /* Section F.2.2.1: decode the DC coefficient difference */
//                  HUFF_DECODE(s, br_state, tbl, return FALSE, label1);
                    {
                    int nb = 0, look;
                    if (bits_left < HUFF_LOOKAHEAD) {
                        if (! jpeg_fill_bit_buffer(br_state,get_buffer,bits_left, 0)) {
                            return false;
                        }
                        get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                        if (bits_left < HUFF_LOOKAHEAD) {
                            nb = 1;
//                          goto slowlabel;
                            if ((s=jpeg_huff_decode(br_state,get_buffer,bits_left,tbl,nb)) < 0) {
                                return false;
                            }
                            get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                        }
                    }
                    if (nb !is 1) {
//                      look = PEEK_BITS(HUFF_LOOKAHEAD);
                        look = (( (get_buffer >> (bits_left -   (HUFF_LOOKAHEAD)))) & ((1<<(HUFF_LOOKAHEAD))-1));

                        if ((nb = tbl.look_nbits[look]) !is 0) {
//                          DROP_BITS(nb);
                            bits_left -= nb;
                            s = tbl.look_sym[look] & 0xFF;
                        } else {
                            nb = HUFF_LOOKAHEAD+1;
//                          slowlabel:
                            if ((s=jpeg_huff_decode(br_state,get_buffer,bits_left,tbl,nb)) < 0) {
                                return false;
                            }
                            get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                        }
                    }
                    }
                    if (s !is 0) {
//                      CHECK_BIT_BUFFER(br_state, s, return FALSE);
                        {
                        if (bits_left < (s)) {
                            if (! jpeg_fill_bit_buffer(br_state,get_buffer,bits_left,s)) {
                                return false;
                            }
                            get_buffer = br_state.get_buffer; bits_left = br_state.bits_left;
                        }
                        }
//                      r = GET_BITS(s);
                        r = (( (get_buffer >> (bits_left -= (s)))) & ((1<<(s))-1));
//                      s = HUFF_EXTEND(r, s);
                        s = ((r) < extend_test[s] ? (r) + extend_offset[s] : (r));
                    }

                        /* Convert DC difference to actual value, update last_dc_val */
                    s += state.last_dc_val[ci];
                    state.last_dc_val[ci] = s;
                    /* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */
                    block[0] = cast(short) (s << Al);
                }

                /* Completed MCU, so update state */
//              BITREAD_SAVE_STATE(cinfo,entropy.bitstate);
                cinfo.buffer = br_state.buffer;
                cinfo.bytes_in_buffer = br_state.bytes_in_buffer;
                cinfo.bytes_offset = br_state.bytes_offset;
                entropy.bitstate.get_buffer = get_buffer;
                entropy.bitstate.bits_left = bits_left;
//              ASSIGN_STATE(entropy.saved, state);
                entropy.saved.EOBRUN = state.EOBRUN;
                entropy.saved.last_dc_val[0] = state.last_dc_val[0];
                entropy.saved.last_dc_val[1] = state.last_dc_val[1];
                entropy.saved.last_dc_val[2] = state.last_dc_val[2];
                entropy.saved.last_dc_val[3] = state.last_dc_val[3];
            }

            /* Account for restart interval (no-op if not using restarts) */
            entropy.restarts_to_go--;

            return true;
        }

        bool process_restart (jpeg_decompress_struct cinfo) {
            phuff_entropy_decoder entropy = this;
            int ci;

            /* Throw away any unused bits remaining in bit buffer; */
            /* include any full bytes in next_marker's count of discarded bytes */
            cinfo.marker.discarded_bytes += entropy.bitstate.bits_left / 8;
            entropy.bitstate.bits_left = 0;

            /* Advance past the RSTn marker */
            if (! read_restart_marker (cinfo))
                return false;

            /* Re-initialize DC predictions to 0 */
            for (ci = 0; ci < cinfo.comps_in_scan; ci++)
                entropy.saved.last_dc_val[ci] = 0;
                /* Re-init EOB run count, too */
            entropy.saved.EOBRUN = 0;

            /* Reset restart counter */
            entropy.restarts_to_go = cinfo.restart_interval;

            /* Reset out-of-data flag, unless read_restart_marker left us smack up
             * against a marker.    In that case we will end up treating the next data
             * segment as empty, and we can avoid producing bogus output pixels by
             * leaving the flag set.
             */
            if (cinfo.unread_marker is 0)
                entropy.insufficient_data = false;

            return true;
        }

        void start_pass_phuff_decoder (jpeg_decompress_struct cinfo) {
            phuff_entropy_decoder entropy = this;
            bool is_DC_band, bad;
            int ci, coefi, tbl;
            int[] coef_bit_ptr;
            jpeg_component_info compptr;

            is_DC_band = (cinfo.Ss is 0);

            /* Validate scan parameters */
            bad = false;
            if (is_DC_band) {
                if (cinfo.Se !is 0)
                    bad = true;
            } else {
                /* need not check Ss/Se < 0 since they came from unsigned bytes */
                if (cinfo.Ss > cinfo.Se || cinfo.Se >= DCTSIZE2)
                    bad = true;
                /* AC scans may have only one component */
                if (cinfo.comps_in_scan !is 1)
                    bad = true;
            }
            if (cinfo.Ah !is 0) {
                /* Successive approximation refinement scan: must have Al = Ah-1. */
                if (cinfo.Al !is cinfo.Ah-1)
                    bad = true;
            }
            if (cinfo.Al > 13)      /* need not check for < 0 */
                bad = true;
            /* Arguably the maximum Al value should be less than 13 for 8-bit precision,
             * but the spec doesn't say so, and we try to be liberal about what we
             * accept.  Note: large Al values could result in out-of-range DC
             * coefficients during early scans, leading to bizarre displays due to
             * overflows in the IDCT math.  But we won't crash.
             */
            if (bad)
                error();
//              ERREXIT4(cinfo, JERR_BAD_PROGRESSION, cinfo.Ss, cinfo.Se, cinfo.Ah, cinfo.Al);
            /* Update progression status, and verify that scan order is legal.
             * Note that inter-scan inconsistencies are treated as warnings
             * not fatal errors ... not clear if this is right way to behave.
             */
            for (ci = 0; ci < cinfo.comps_in_scan; ci++) {
                int cindex = cinfo.cur_comp_info[ci].component_index;
                coef_bit_ptr = cinfo.coef_bits[cindex];
                if (!is_DC_band && coef_bit_ptr[0] < 0) {/* AC without prior DC scan */
//                  WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);
                }
                for (coefi = cinfo.Ss; coefi <= cinfo.Se; coefi++) {
                    int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];
                    if (cinfo.Ah !is expected) {
//                      WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);
                    }
                    coef_bit_ptr[coefi] = cinfo.Al;
                }
            }

            /* Select MCU decoding routine */
//          if (cinfo.Ah is 0) {
//              if (is_DC_band)
//                  entropy.pub.decode_mcu = decode_mcu_DC_first;
//              else
//                  entropy.pub.decode_mcu = decode_mcu_AC_first;
//          } else {
//              if (is_DC_band)
//                  entropy.pub.decode_mcu = decode_mcu_DC_refine;
//              else
//                  entropy.pub.decode_mcu = decode_mcu_AC_refine;
//          }

            for (ci = 0; ci < cinfo.comps_in_scan; ci++) {
                compptr = cinfo.cur_comp_info[ci];
                /* Make sure requested tables are present, and compute derived tables.
                 * We may build same derived table more than once, but it's not expensive.
                 */
                if (is_DC_band) {
                    if (cinfo.Ah is 0) {    /* DC refinement needs no table */
                        tbl = compptr.dc_tbl_no;
                        jpeg_make_d_derived_tbl(cinfo, true, tbl, entropy.derived_tbls[tbl] = new d_derived_tbl());
                    }
                } else {
                    tbl = compptr.ac_tbl_no;
                    jpeg_make_d_derived_tbl(cinfo, false, tbl, entropy.derived_tbls[tbl] = new d_derived_tbl());
                    /* remember the single active table */
                    entropy.ac_derived_tbl = entropy.derived_tbls[tbl];
                }
                /* Initialize DC predictions to 0 */
                entropy.saved.last_dc_val[ci] = 0;
            }

            /* Initialize bitread state variables */
            entropy.bitstate.bits_left = 0;
            entropy.bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
            entropy.insufficient_data = false;

            /* Initialize private state variables */
            entropy.saved.EOBRUN = 0;

            /* Initialize restart counter */
            entropy.restarts_to_go = cinfo.restart_interval;
        }

    }

    static final class jpeg_component_info {
        /* These values are fixed over the whole image. */
        /* For compression, they must be supplied by parameter setup; */
        /* for decompression, they are read from the SOF marker. */
        int component_id;       /* identifier for this component (0..255) */
        int component_index;        /* its index in SOF or cinfo.comp_info[] */
        int h_samp_factor;      /* horizontal sampling factor (1..4) */
        int v_samp_factor;      /* vertical sampling factor (1..4) */
        int quant_tbl_no;       /* quantization table selector (0..3) */
        /* These values may vary between scans. */
        /* For compression, they must be supplied by parameter setup; */
        /* for decompression, they are read from the SOS marker. */
        /* The decompressor output side may not use these variables. */
        int dc_tbl_no;      /* DC entropy table selector (0..3) */
        int ac_tbl_no;      /* AC entropy table selector (0..3) */

        /* Remaining fields should be treated as private by applications. */

        /* These values are computed during compression or decompression startup: */
        /* Component's size in DCT blocks.
         * Any dummy blocks added to complete an MCU are not counted; therefore
         * these values do not depend on whether a scan is interleaved or not.
         */
        int width_in_blocks;
        int height_in_blocks;
        /* Size of a DCT block in samples.  Always DCTSIZE for compression.
         * For decompression this is the size of the output from one DCT block,
         * reflecting any scaling we choose to apply during the IDCT step.
         * Values of 1,2,4,8 are likely to be supported.    Note that different
         * components may receive different IDCT scalings.
         */
        int DCT_scaled_size;
        /* The downsampled dimensions are the component's actual, unpadded number
         * of samples at the main buffer (preprocessing/compression interface), thus
         * downsampled_width = ceil(image_width * Hi/Hmax)
         * and similarly for height.    For decompression, IDCT scaling is included, so
         * downsampled_width = ceil(image_width * Hi/Hmax * DCT_scaled_size/DCTSIZE)
         */
        int downsampled_width;   /* actual width in samples */
        int downsampled_height; /* actual height in samples */
        /* This flag is used only for decompression.    In cases where some of the
         * components will be ignored (eg grayscale output from YCbCr image),
         * we can skip most computations for the unused components.
         */
        bool component_needed;   /* do we need the value of this component? */

        /* These values are computed before starting a scan of the component. */
        /* The decompressor output side may not use these variables. */
        int MCU_width;      /* number of blocks per MCU, horizontally */
        int MCU_height;     /* number of blocks per MCU, vertically */
        int MCU_blocks;     /* MCU_width * MCU_height */
        int MCU_sample_width;       /* MCU width in samples, MCU_width*DCT_scaled_size */
        int last_col_width;     /* # of non-dummy blocks across in last MCU */
        int last_row_height;        /* # of non-dummy blocks down in last MCU */

        /* Saved quantization table for component; null if none yet saved.
         * See jdinput.c comments about the need for this information.
         * This field is currently used only for decompression.
         */
        JQUANT_TBL quant_table;

        /* Private per-component storage for DCT or IDCT subsystem. */
        int[] dct_table;
    }

    static final class jpeg_color_quantizer {
//      JMETHOD(void, start_pass, (j_decompress_ptr cinfo, bool is_pre_scan));
//      JMETHOD(void, color_quantize, (j_decompress_ptr cinfo,
//                   JSAMPARRAY input_buf, JSAMPARRAY output_buf,
//                   int num_rows));
//      JMETHOD(void, finish_pass, (j_decompress_ptr cinfo));
//      JMETHOD(void, new_color_map, (j_decompress_ptr cinfo));

        /* Initially allocated colormap is saved here */
        int[][] sv_colormap;    /* The color map as a 2-D pixel array */
        int sv_actual;      /* number of entries in use */

        int[][] colorindex; /* Precomputed mapping for speed */
        /* colorindex[i][j] = index of color closest to pixel value j in component i,
         * premultiplied as described above.    Since colormap indexes must fit into
         * JSAMPLEs, the entries of this array will too.
         */
        bool is_padded;      /* is the colorindex padded for odither? */

        int[MAX_Q_COMPS] Ncolors;// = new int [MAX_Q_COMPS];    /* # of values alloced to each component */

        /* Variables for ordered dithering */
        int row_index;      /* cur row's vertical index in dither matrix */
//          ODITHER_MATRIX_PTR odither[MAX_Q_COMPS]; /* one dither array per component */

        /* Variables for Floyd-Steinberg dithering */
//          FSERRPTR fserrors[MAX_Q_COMPS]; /* accumulated errors */
        bool on_odd_row; 

        void start_pass (jpeg_decompress_struct cinfo, bool is_pre_scan) {
            error();
        }
    }

    static final class jpeg_upsampler {
//      JMETHOD(void, start_pass, (j_decompress_ptr cinfo));
//      JMETHOD(void, upsample, (j_decompress_ptr cinfo,
//                   JSAMPIMAGE input_buf,
//                   JDIMENSION *in_row_group_ctr,
//                   JDIMENSION in_row_groups_avail,
//                   JSAMPARRAY output_buf,
//                   JDIMENSION *out_row_ctr,
//                   JDIMENSION out_rows_avail));

        bool need_context_rows;  /* TRUE if need rows above & below */

        /* Color conversion buffer. When using separate upsampling and color
         * conversion steps, this buffer holds one upsampled row group until it
         * has been color converted and output.
         * Note: we do not allocate any storage for component(s) which are full-size,
         * ie do not need rescaling.    The corresponding entry of color_buf[] is
         * simply set to point to the input data array, thereby avoiding copying.
         */
        byte[][][MAX_COMPONENTS] color_buf;// = new byte[MAX_COMPONENTS][][];
        int[MAX_COMPONENTS] color_buf_offset;// = new int[MAX_COMPONENTS];

        /* Per-component upsampling method pointers */
        int[MAX_COMPONENTS] methods;// = new int[MAX_COMPONENTS];

        int next_row_out;       /* counts rows emitted from color_buf */
        int rows_to_go; /* counts rows remaining in image */

        /* Height of an input row group for each component. */
        int[MAX_COMPONENTS] rowgroup_height;// = new int[MAX_COMPONENTS];

        /* These arrays save pixel expansion factors so that int_expand need not
         * recompute them each time.    They are unused for other upsampling methods.
         */
        byte[MAX_COMPONENTS] h_expand;// = new byte[MAX_COMPONENTS];
        byte[MAX_COMPONENTS] v_expand;// = new byte[MAX_COMPONENTS];

        void start_pass (jpeg_decompress_struct cinfo) {
            jpeg_upsampler upsample = cinfo.upsample;

            /* Mark the conversion buffer empty */
            upsample.next_row_out = cinfo.max_v_samp_factor;
            /* Initialize total-height counter for detecting bottom of image */
            upsample.rows_to_go = cinfo.output_height;
        }

    }

    static final class jpeg_marker_reader {
        /* Read a restart marker --- exported for use by entropy decoder only */
//      jpeg_marker_parser_method read_restart_marker;

        /* State of marker reader --- nominally internal, but applications
         * supplying COM or APPn handlers might like to know the state.
         */
        bool saw_SOI;        /* found SOI? */
        bool saw_SOF;        /* found SOF? */
        int next_restart_num;       /* next restart number expected (0-7) */
        int discarded_bytes;    /* # of bytes skipped looking for a marker */

        /* Application-overridable marker processing methods */
//      jpeg_marker_parser_method process_COM;
//      jpeg_marker_parser_method process_APPn[16];

        /* Limit on marker data length to save for each marker type */
        int length_limit_COM;
        int[16] length_limit_APPn;// = new int[16];

        /* Status of COM/APPn marker saving */
//      jpeg_marker_reader cur_marker;  /* null if not processing a marker */
//      int bytes_read;     /* data bytes read so far in marker */
        /* Note: cur_marker is not linked into marker_list until it's all read. */
    }


    static final class jpeg_d_main_controller {
//      JMETHOD(void, start_pass, (j_decompress_ptr cinfo, J_BUF_MODE pass_mode));
        int process_data;

         /* Pointer to allocated workspace (M or M+2 row groups). */
        byte[][][MAX_COMPONENTS] buffer;// = new byte[MAX_COMPONENTS][][];
        int[MAX_COMPONENTS] buffer_offset;// = new int[MAX_COMPONENTS];

        bool buffer_full;        /* Have we gotten an iMCU row from decoder? */
        int[1] rowgroup_ctr;// = new int[1];    /* counts row groups output to postprocessor */

        /* Remaining fields are only used in the context case. */

        /* These are the master pointers to the funny-order pointer lists. */
        byte[][][][2] xbuffer;// = new byte[2][][][];   /* pointers to weird pointer lists */
        int[][2] xbuffer_offset;// = new int[2][];

        int whichptr;           /* indicates which pointer set is now in use */
        int context_state;      /* process_data state machine status */
        int rowgroups_avail;    /* row groups available to postprocessor */
        int iMCU_row_ctr;   /* counts iMCU rows to detect image top/bot */

        void start_pass (jpeg_decompress_struct cinfo, int pass_mode) {
            jpeg_d_main_controller main = cinfo.main;

            switch (pass_mode) {
                case JBUF_PASS_THRU:
                    if (cinfo.upsample.need_context_rows) {
                        main.process_data = PROCESS_DATA_CONTEXT_MAIN;
                        make_funny_pointers(cinfo); /* Create the xbuffer[] lists */
                        main.whichptr = 0;  /* Read first iMCU row into xbuffer[0] */
                        main.context_state = CTX_PREPARE_FOR_IMCU;
                        main.iMCU_row_ctr = 0;
                    } else {
                        /* Simple case with no context needed */
                        main.process_data = PROCESS_DATA_SIMPLE_MAIN;
                    }
                    main.buffer_full = false;   /* Mark buffer empty */
                    main.rowgroup_ctr[0] = 0;
                    break;
//              #ifdef QUANT_2PASS_SUPPORTED
//              case JBUF_CRANK_DEST:
//                  /* For last pass of 2-pass quantization, just crank the postprocessor */
//                  main.process_data = PROCESS_DATA_CRANK_POST;
//                  break;
//              #endif
                default:
                    error();
//                  ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
                    break;
            }
        }

    }

    static final class jpeg_decomp_master {
//      JMETHOD(void, prepare_for_output_pass, (j_decompress_ptr cinfo));
//      JMETHOD(void, finish_output_pass, (j_decompress_ptr cinfo));

        /* State variables made visible to other modules */
        bool is_dummy_pass;

        int pass_number;        /* # of passes completed */

        bool using_merged_upsample; /* true if using merged upsample/cconvert */

        /* Saved references to initialized quantizer modules,
         * in case we need to switch modes.
         */
        jpeg_color_quantizer quantizer_1pass;
        jpeg_color_quantizer quantizer_2pass;
    }

    static final class jpeg_inverse_dct {
//      JMETHOD(void, start_pass, (j_decompress_ptr cinfo));
//      /* It is useful to allow each component to have a separate IDCT method. */
//      inverse_DCT_method_ptr inverse_DCT[MAX_COMPONENTS];
        int[MAX_COMPONENTS] cur_method;// = new int[MAX_COMPONENTS];

        void start_pass (jpeg_decompress_struct cinfo) {
            jpeg_inverse_dct idct = cinfo.idct;
            int ci, i;
            jpeg_component_info compptr;
            int method = 0;
//          inverse_DCT_method_ptr method_ptr = NULL;
            JQUANT_TBL qtbl;

            for (ci = 0; ci < cinfo.num_components; ci++) {
                compptr = cinfo.comp_info[ci];
                /* Select the proper IDCT routine for this component's scaling */
                switch (compptr.DCT_scaled_size) {
//                  #ifdef IDCT_SCALING_SUPPORTED
//                  case 1:
//                      method_ptr = jpeg_idct_1x1;
//                      method = JDCT_ISLOW;    /* jidctred uses islow-style table */
//                      break;
//                  case 2:
//                      method_ptr = jpeg_idct_2x2;
//                      method = JDCT_ISLOW;    /* jidctred uses islow-style table */
//                      break;
//                  case 4:
//                      method_ptr = jpeg_idct_4x4;
//                      method = JDCT_ISLOW;    /* jidctred uses islow-style table */
//                      break;
//                  #endif
                    case DCTSIZE:
                        switch (cinfo.dct_method) {
//                          #ifdef DCT_ISLOW_SUPPORTED
                            case JDCT_ISLOW:
//                              method_ptr = jpeg_idct_islow;
                                method = JDCT_ISLOW;
                                break;
//                          #endif
//                          #ifdef DCT_IFAST_SUPPORTED
//                          case JDCT_IFAST:
//                              method_ptr = jpeg_idct_ifast;
//                              method = JDCT_IFAST;
//                              break;
//                          #endif
//                          #ifdef DCT_FLOAT_SUPPORTED
//                          case JDCT_FLOAT:
//                              method_ptr = jpeg_idct_float;
//                              method = JDCT_FLOAT;
//                              break;
//                          #endif
                            default:
                                error();
//                              ERREXIT(cinfo, JERR_NOT_COMPILED);
                                break;
                        }
                        break;
                    default:
                        error();
//                      ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr.DCT_scaled_size);
                        break;
                    }
//                  idct.inverse_DCT[ci] = method_ptr;
                    /* Create multiplier table from quant table.
                     * However, we can skip this if the component is uninteresting
                     * or if we already built the table.    Also, if no quant table
                     * has yet been saved for the component, we leave the
                     * multiplier table all-zero; we'll be reading zeroes from the
                     * coefficient controller's buffer anyway.
                     */
                    if (! compptr.component_needed || idct.cur_method[ci] is method)
                        continue;
                    qtbl = compptr.quant_table;
                    if (qtbl is null)       /* happens if no data yet for component */
                        continue;
                    idct.cur_method[ci] = method;
                    switch (method) {
//                      #ifdef PROVIDE_ISLOW_TABLES
                        case JDCT_ISLOW:
                        {
                            /* For LL&M IDCT method, multipliers are equal to raw quantization
                             * coefficients, but are stored as ints to ensure access efficiency.
                             */
                            int[] ismtbl = compptr.dct_table;
                            for (i = 0; i < DCTSIZE2; i++) {
                                ismtbl[i] = qtbl.quantval[i];
                            }
                        }
                        break;
//                      #endif
//                      #ifdef DCT_IFAST_SUPPORTED
//                      case JDCT_IFAST:
//                      {
//                          /* For AA&N IDCT method, multipliers are equal to quantization
//                           * coefficients scaled by scalefactor[row]*scalefactor[col], where
//                           *   scalefactor[0] = 1
//                           *   scalefactor[k] = cos(k*PI/16) * sqrt(2)        for k=1..7
//                           * For integer operation, the multiplier table is to be scaled by
//                           * IFAST_SCALE_BITS.
//                           */
//                          int[] ifmtbl = compptr.dct_table;
//                          short aanscales[] = {
//                              /* precomputed values scaled up by 14 bits */
//                              16384, 22725, 21407, 19266, 16384, 12873,   8867,   4520,
//                              22725, 31521, 29692, 26722, 22725, 17855, 12299,    6270,
//                              21407, 29692, 27969, 25172, 21407, 16819, 11585,    5906,
//                              19266, 26722, 25172, 22654, 19266, 15137, 10426,    5315,
//                              16384, 22725, 21407, 19266, 16384, 12873,   8867,   4520,
//                              12873, 17855, 16819, 15137, 12873, 10114,   6967,   3552,
//                              8867, 12299, 11585, 10426,  8867,   6967,   4799,   2446,
//                              4520,   6270,   5906,   5315,   4520,   3552,   2446,   1247
//                          };
//                          SHIFT_TEMPS
//
//                          for (i = 0; i < DCTSIZE2; i++) {
//                              ifmtbl[i] = DESCALE(MULTIPLY16V16( qtbl.quantval[i], aanscales[i]), CONST_BITS-IFAST_SCALE_BITS);
//                          }
//                      }
//                      break;
//                      #endif
//                      #ifdef DCT_FLOAT_SUPPORTED
//                      case JDCT_FLOAT:
//                      {
//                          /* For float AA&N IDCT method, multipliers are equal to quantization
//                           * coefficients scaled by scalefactor[row]*scalefactor[col], where
//                           *   scalefactor[0] = 1
//                           *   scalefactor[k] = cos(k*PI/16) * sqrt(2)        for k=1..7
//                           */
//                          FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr.dct_table;
//                          int row, col;
//                          static const double aanscalefactor[DCTSIZE] = {
//                              1.0, 1.387039845, 1.306562965, 1.175875602,
//                              1.0, 0.785694958, 0.541196100, 0.275899379
//                          };
//
//                          i = 0;
//                          for (row = 0; row < DCTSIZE; row++) {
//                              for (col = 0; col < DCTSIZE; col++) {
//                                  fmtbl[i] = (FLOAT_MULT_TYPE)
//                                      ((double) qtbl.quantval[i] *
//                                   aanscalefactor[row] * aanscalefactor[col]);
//                                  i++;
//                              }
//                          }
//                      }
//                      break;
//                      #endif
                    default:
                        error();
//                      ERREXIT(cinfo, JERR_NOT_COMPILED);
                        break;
                }
            }
        }
    }

    static final class jpeg_input_controller {
        int consume_input;
        bool has_multiple_scans; /* True if file has multiple scans */
        bool eoi_reached;

        bool inheaders;      /* true until first SOS is reached */
    }

    static final class  jpeg_color_deconverter {
//      JMETHOD(void, start_pass, (j_decompress_ptr cinfo));
        int color_convert;

        /* Private state for YCC.RGB conversion */
        int[] Cr_r_tab;     /* => table for Cr to R conversion */
        int[] Cb_b_tab;     /* => table for Cb to B conversion */
        int[] Cr_g_tab;     /* => table for Cr to G conversion */
        int[] Cb_g_tab;     /* => table for Cb to G conversion */

        void start_pass (jpeg_decompress_struct cinfo) {
            /* no work needed */
        }

    }

    static final class jpeg_d_post_controller {
//      JMETHOD(void, start_pass, (j_decompress_ptr cinfo, J_BUF_MODE pass_mode));
        int post_process_data;

        /* Color quantization source buffer: this holds output data from
         * the upsample/color conversion step to be passed to the quantizer.
         * For two-pass color quantization, we need a full-image buffer;
         * for one-pass operation, a strip buffer is sufficient.
         */
        int[] whole_image;  /* virtual array, or NULL if one-pass */
        int[][] buffer;     /* strip buffer, or current strip of virtual */
        int strip_height;   /* buffer size in rows */
        /* for two-pass mode only: */
        int starting_row;   /* row # of first row in current strip */
        int next_row;       /* index of next row to fill/empty in strip */

        void start_pass (jpeg_decompress_struct cinfo, int pass_mode) {
            jpeg_d_post_controller post = cinfo.post;

            switch (pass_mode) {
                case JBUF_PASS_THRU:
                    if (cinfo.quantize_colors) {
                        error(SWT.ERROR_NOT_IMPLEMENTED);
//                      /* Single-pass processing with color quantization. */
//                      post.post_process_data = POST_PROCESS_1PASS;
//                      /* We could be doing buffered-image output before starting a 2-pass
//                       * color quantization; in that case, jinit_d_post_controller did not
//                       * allocate a strip buffer. Use the virtual-array buffer as workspace.
//                       */
//                      if (post.buffer is null) {
//                          post.buffer = (*cinfo.mem.access_virt_sarray)
//                              ((j_common_ptr) cinfo, post.whole_image,
//                              (JDIMENSION) 0, post.strip_height, TRUE);
//                      }
                    } else {
                        /* For single-pass processing without color quantization,
                         * I have no work to do; just call the upsampler directly.
                         */
                        post.post_process_data = POST_PROCESS_DATA_UPSAMPLE;
                    }
                    break;
//              #ifdef QUANT_2PASS_SUPPORTED
//              case JBUF_SAVE_AND_PASS:
//                  /* First pass of 2-pass quantization */
//                  if (post.whole_image is NULL)
//                      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
//                  post.pub.post_process_data = post_process_prepass;
//                  break;
//              case JBUF_CRANK_DEST:
//                  /* Second pass of 2-pass quantization */
//                  if (post.whole_image is NULL)
//                      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
//                  post.pub.post_process_data = post_process_2pass;
//                  break;
//              #endif /* QUANT_2PASS_SUPPORTED */
                    default:
                        error();
//                      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
                        break;
            }
            post.starting_row = post.next_row = 0;
        }

    }

    static final class jpeg_decompress_struct {
//      jpeg_error_mgr * err;   /* Error handler module */\
//      struct jpeg_memory_mgr * mem;   /* Memory manager module */\
//      struct jpeg_progress_mgr * progress; /* Progress monitor, or null if none */\
//      void * client_data;     /* Available for use by application */\
        bool is_decompressor;    /* So common code can tell which is which */
        int global_state;       /* For checking call sequence validity */

//      /* Source of compressed data */
//      struct jpeg_source_mgr * src;
        InputStream inputStream;
        byte[] buffer;
        int bytes_in_buffer;
        int bytes_offset;
        bool start_of_file;

        /* Basic description of image --- filled in by jpeg_read_header(). */
        /* Application may inspect these values to decide how to process image. */

        int image_width;    /* nominal image width (from SOF marker) */
        int image_height;   /* nominal image height */
        int num_components;     /* # of color components in JPEG image */
        int jpeg_color_space; /* colorspace of JPEG image */

        /* Decompression processing parameters --- these fields must be set before
         * calling jpeg_start_decompress(). Note that jpeg_read_header() initializes
         * them to default values.
         */

        int out_color_space; /* colorspace for output */

        int scale_num, scale_denom; /* fraction by which to scale image */

        double output_gamma;        /* image gamma wanted in output */

        bool buffered_image; /* true=multiple output passes */
        bool raw_data_out;       /* true=downsampled data wanted */

        int dct_method; /* IDCT algorithm selector */
        bool do_fancy_upsampling;    /* true=apply fancy upsampling */
        bool do_block_smoothing; /* true=apply interblock smoothing */

        bool quantize_colors;    /* true=colormapped output wanted */
        /* the following are ignored if not quantize_colors: */
        int dither_mode;    /* type of color dithering to use */
        bool two_pass_quantize;  /* true=use two-pass color quantization */
        int desired_number_of_colors;   /* max # colors to use in created colormap */
        /* these are significant only in buffered-image mode: */
        bool enable_1pass_quant; /* enable future use of 1-pass quantizer */
        bool enable_external_quant;/* enable future use of external colormap */
        bool enable_2pass_quant; /* enable future use of 2-pass quantizer */

        /* Description of actual output image that will be returned to application.
         * These fields are computed by jpeg_start_decompress().
         * You can also use jpeg_calc_output_dimensions() to determine these values
         * in advance of calling jpeg_start_decompress().
         */

        int output_width;   /* scaled image width */
        int output_height;  /* scaled image height */
        int out_color_components;   /* # of color components in out_color_space */
        int output_components;  /* # of color components returned */
        /* output_components is 1 (a colormap index) when quantizing colors;
         * otherwise it equals out_color_components.
         */
        int rec_outbuf_height;  /* min recommended height of scanline buffer */
        /* If the buffer passed to jpeg_read_scanlines() is less than this many rows
         * high, space and time will be wasted due to unnecessary data copying.
         * Usually rec_outbuf_height will be 1 or 2, at most 4.
         */

        /* When quantizing colors, the output colormap is described by these fields.
         * The application can supply a colormap by setting colormap non-null before
         * calling jpeg_start_decompress; otherwise a colormap is created during
         * jpeg_start_decompress or jpeg_start_output.
         * The map has out_color_components rows and actual_number_of_colors columns.
         */
        int actual_number_of_colors;    /* number of entries in use */
        int[] colormap;     /* The color map as a 2-D pixel array */

        /* State variables: these variables indicate the progress of decompression.
         * The application may examine these but must not modify them.
         */

        /* Row index of next scanline to be read from jpeg_read_scanlines().
         * Application may use this to control its processing loop, e.g.,
         * "while (output_scanline < output_height)".
         */
        int output_scanline;    /* 0 .. output_height-1 */

        /* Current input scan number and number of iMCU rows completed in scan.
         * These indicate the progress of the decompressor input side.
         */
        int input_scan_number;  /* Number of SOS markers seen so far */
        int input_iMCU_row; /* Number of iMCU rows completed */

        /* The "output scan number" is the notional scan being displayed by the
         * output side. The decompressor will not allow output scan/row number
         * to get ahead of input scan/row, but it can fall arbitrarily far behind.
         */
        int output_scan_number; /* Nominal scan number being displayed */
        int output_iMCU_row;    /* Number of iMCU rows read */

        /* Current progression status.  coef_bits[c][i] indicates the precision
         * with which component c's DCT coefficient i (in zigzag order) is known.
         * It is -1 when no data has yet been received, otherwise it is the point
         * transform (shift) value for the most recent scan of the coefficient
         * (thus, 0 at completion of the progression).
         * This pointer is null when reading a non-progressive file.
         */
        int[][] coef_bits;  /* -1 or current Al value for each coef */

        /* Internal JPEG parameters --- the application usually need not look at
         * these fields.    Note that the decompressor output side may not use
         * any parameters that can change between scans.
         */

        /* Quantization and Huffman tables are carried forward across input
         * datastreams when processing abbreviated JPEG datastreams.
         */

        JQUANT_TBL[NUM_QUANT_TBLS] quant_tbl_ptrs;// = new JQUANT_TBL[NUM_QUANT_TBLS];
        /* ptrs to coefficient quantization tables, or null if not defined */

        JHUFF_TBL[NUM_HUFF_TBLS] dc_huff_tbl_ptrs;// = new JHUFF_TBL[NUM_HUFF_TBLS];
        JHUFF_TBL[NUM_HUFF_TBLS] ac_huff_tbl_ptrs;// = new JHUFF_TBL[NUM_HUFF_TBLS];
        /* ptrs to Huffman coding tables, or null if not defined */

        /* These parameters are never carried across datastreams, since they
         * are given in SOF/SOS markers or defined to be reset by SOI.
         */

        int data_precision;     /* bits of precision in image data */

        jpeg_component_info[] comp_info;
        /* comp_info[i] describes component that appears i'th in SOF */

        bool progressive_mode;   /* true if SOFn specifies progressive mode */
        bool arith_code;     /* true=arithmetic coding, false=Huffman */

        byte[NUM_ARITH_TBLS] arith_dc_L;// = new byte[NUM_ARITH_TBLS]; /* L values for DC arith-coding tables */
        byte[NUM_ARITH_TBLS] arith_dc_U;// = new byte[NUM_ARITH_TBLS]; /* U values for DC arith-coding tables */
        byte[NUM_ARITH_TBLS] arith_ac_K;// = new byte[NUM_ARITH_TBLS]; /* Kx values for AC arith-coding tables */

        int restart_interval; /* MCUs per restart interval, or 0 for no restart */

        /* These fields record data obtained from optional markers recognized by
         * the JPEG library.
         */
        bool saw_JFIF_marker;    /* true iff a JFIF APP0 marker was found */
        /* Data copied from JFIF marker; only valid if saw_JFIF_marker is true: */
        byte JFIF_major_version;    /* JFIF version number */
        byte JFIF_minor_version;
        byte density_unit;      /* JFIF code for pixel size units */
        short X_density;        /* Horizontal pixel density */
        short Y_density;        /* Vertical pixel density */
        bool saw_Adobe_marker;   /* true iff an Adobe APP14 marker was found */
        byte Adobe_transform;   /* Color transform code from Adobe marker */

        bool CCIR601_sampling;   /* true=first samples are cosited */

        /* Aside from the specific data retained from APPn markers known to the
         * library, the uninterpreted contents of any or all APPn and COM markers
         * can be saved in a list for examination by the application.
         */
        jpeg_marker_reader marker_list; /* Head of list of saved markers */

        /* Remaining fields are known throughout decompressor, but generally
         * should not be touched by a surrounding application.
         */

        /*
         * These fields are computed during decompression startup
         */
        int max_h_samp_factor;  /* largest h_samp_factor */
        int max_v_samp_factor;  /* largest v_samp_factor */

        int min_DCT_scaled_size;    /* smallest DCT_scaled_size of any component */

        int total_iMCU_rows;    /* # of iMCU rows in image */
        /* The coefficient controller's input and output progress is measured in
         * units of "iMCU" (interleaved MCU) rows.  These are the same as MCU rows
         * in fully interleaved JPEG scans, but are used whether the scan is
         * interleaved or not.  We define an iMCU row as v_samp_factor DCT block
         * rows of each component.  Therefore, the IDCT output contains
         * v_samp_factor*DCT_scaled_size sample rows of a component per iMCU row.
         */

        byte[] sample_range_limit; /* table for fast range-limiting */
        int sample_range_limit_offset;

        /*
         * These fields are valid during any one scan.
         * They describe the components and MCUs actually appearing in the scan.
         * Note that the decompressor output side must not use these fields.
         */
        int comps_in_scan;      /* # of JPEG components in this scan */
        jpeg_component_info[MAX_COMPS_IN_SCAN] cur_comp_info;// = new jpeg_component_info[MAX_COMPS_IN_SCAN];
        /* *cur_comp_info[i] describes component that appears i'th in SOS */

        int MCUs_per_row;   /* # of MCUs across the image */
        int MCU_rows_in_scan;   /* # of MCU rows in the image */

        int blocks_in_MCU;      /* # of DCT blocks per MCU */
        int[D_MAX_BLOCKS_IN_MCU] MCU_membership;// = new int[D_MAX_BLOCKS_IN_MCU];
        /* MCU_membership[i] is index in cur_comp_info of component owning */
        /* i'th block in an MCU */

        int Ss, Se, Ah, Al;     /* progressive JPEG parameters for scan */

        /* This field is shared between entropy decoder and marker parser.
         * It is either zero or the code of a JPEG marker that has been
         * read from the data source, but has not yet been processed.
         */
        int unread_marker;

        int[DCTSIZE2] workspace;// = new int[DCTSIZE2];
        int[1] row_ctr;// = new int[1];

        /*
         * Links to decompression subobjects (methods, private variables of modules)
         */
        jpeg_decomp_master master;
        jpeg_d_main_controller main;
        jpeg_d_coef_controller coef;
        jpeg_d_post_controller post;
        jpeg_input_controller inputctl;
        jpeg_marker_reader marker;
        jpeg_entropy_decoder entropy;
        jpeg_inverse_dct idct;
        jpeg_upsampler upsample;
        jpeg_color_deconverter cconvert;
        jpeg_color_quantizer cquantize;
    }

static void error() {
    SWT.error(SWT.ERROR_INVALID_IMAGE);
}

static void error(int code) {
    SWT.error(code);
}

static void error(String msg) {
    SWT.error(SWT.ERROR_INVALID_IMAGE, null, msg);
}

static void jinit_marker_reader (jpeg_decompress_struct cinfo) {
    jpeg_marker_reader marker = cinfo.marker = new jpeg_marker_reader();
//  int i;

    /* Initialize COM/APPn processing.
     * By default, we examine and then discard APP0 and APP14,
     * but simply discard COM and all other APPn.
     */
//  marker.process_COM = skip_variable;
    marker.length_limit_COM = 0;
//  for (i = 0; i < 16; i++) {
//      marker.process_APPn[i] = skip_variable;
//      marker.length_limit_APPn[i] = 0;
//  }
//  marker.process_APPn[0] = get_interesting_appn;
//  marker.process_APPn[14] = get_interesting_appn;
    /* Reset marker processing state */
    reset_marker_reader(cinfo);
}

static void jinit_d_coef_controller (jpeg_decompress_struct cinfo, bool need_full_buffer) {
    jpeg_d_coef_controller coef = new jpeg_d_coef_controller();
    cinfo.coef = coef;
//  coef.pub.start_input_pass = start_input_pass;
//  coef.pub.start_output_pass = start_output_pass;
    coef.coef_bits_latch = null;

    /* Create the coefficient buffer. */
    if (need_full_buffer) {
//#ifdef D_MULTISCAN_FILES_SUPPORTED
        /* Allocate a full-image virtual array for each component, */
        /* padded to a multiple of samp_factor DCT blocks in each direction. */
        /* Note we ask for a pre-zeroed array. */
        int ci, access_rows;
        jpeg_component_info compptr;

        for (ci = 0; ci < cinfo.num_components; ci++) {
            compptr = cinfo.comp_info[ci];
            access_rows = compptr.v_samp_factor;
//#ifdef BLOCK_SMOOTHING_SUPPORTED
            /* If block smoothing could be used, need a bigger window */
            if (cinfo.progressive_mode)
                access_rows *= 3;
//#endif
            coef.whole_image[ci] =
                new short[][][](
                    cast(int)jround_up( compptr.height_in_blocks, compptr.v_samp_factor),
                    cast(int)jround_up( compptr.width_in_blocks, compptr.h_samp_factor),
                    DCTSIZE2
                    );
        }
//      coef.consume_data = consume_data;
        coef.decompress_data = DECOMPRESS_DATA;
        coef.coef_arrays = coef.whole_image[0]; /* link to virtual arrays */
//      #else
//              ERREXIT(cinfo, JERR_NOT_COMPILED);
//      #endif
    } else {
        /* We only need a single-MCU buffer. */
        foreach( ref el; coef.MCU_buffer ){
            el = new short[](DCTSIZE2);
        }
//      coef.consume_data = dummy_consume_data;
        coef.decompress_data = DECOMPRESS_ONEPASS;
        coef.coef_arrays = null; /* flag for no virtual arrays */
    }
}

static void start_output_pass (jpeg_decompress_struct cinfo) {
//#ifdef BLOCK_SMOOTHING_SUPPORTED
    jpeg_d_coef_controller coef = cinfo.coef;

    /* If multipass, check to see whether to use block smoothing on this pass */
    if (coef.coef_arrays !is null) {
        if (cinfo.do_block_smoothing && smoothing_ok(cinfo))
            coef.decompress_data = DECOMPRESS_SMOOTH_DATA;
        else
            coef.decompress_data = DECOMPRESS_DATA;
    }
//#endif
    cinfo.output_iMCU_row = 0;
}

static void jpeg_create_decompress(jpeg_decompress_struct cinfo) {
    cinfo.is_decompressor = true;


    /* Initialize marker processor so application can override methods
     * for COM, APPn markers before calling jpeg_read_header.
     */
    cinfo.marker_list = null;
    jinit_marker_reader(cinfo);

    /* And initialize the overall input controller. */
    jinit_input_controller(cinfo);

    /* OK, I'm ready */
    cinfo.global_state = DSTATE_START;
}

static void jpeg_calc_output_dimensions (jpeg_decompress_struct cinfo)
/* Do computations that are needed before master selection phase */
{
//#ifdef IDCT_SCALING_SUPPORTED
//  int ci;
//  jpeg_component_info compptr;
//#endif

    /* Prevent application from calling me at wrong times */
    if (cinfo.global_state !is DSTATE_READY)
        error();
//      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo.global_state);

//#ifdef IDCT_SCALING_SUPPORTED
//
//  /* Compute actual output image dimensions and DCT scaling choices. */
//  if (cinfo.scale_num * 8 <= cinfo.scale_denom) {
//      /* Provide 1/8 scaling */
//      cinfo.output_width = cast(int)
//          jdiv_round_up(cinfo.image_width, 8L);
//      cinfo.output_height = cast(int)
//          jdiv_round_up(cinfo.image_height, 8L);
//      cinfo.min_DCT_scaled_size = 1;
//  } else if (cinfo.scale_num * 4 <= cinfo.scale_denom) {
//      /* Provide 1/4 scaling */
//      cinfo.output_width = cast(int)
//          jdiv_round_up(cinfo.image_width, 4L);
//      cinfo.output_height = cast(int)
//          jdiv_round_up(cinfo.image_height, 4L);
//      cinfo.min_DCT_scaled_size = 2;
//  } else if (cinfo.scale_num * 2 <= cinfo.scale_denom) {
//      /* Provide 1/2 scaling */
//      cinfo.output_width = cast(int)
//          jdiv_round_up(cinfo.image_width, 2L);
//      cinfo.output_height = cast(int)
//          jdiv_round_up(cinfo.image_height, 2L);
//      cinfo.min_DCT_scaled_size = 4;
//  } else {
//      /* Provide 1/1 scaling */
//      cinfo.output_width = cinfo.image_width;
//      cinfo.output_height = cinfo.image_height;
//      cinfo.min_DCT_scaled_size = DCTSIZE;
//  }
//  /* In selecting the actual DCT scaling for each component, we try to
//   * scale up the chroma components via IDCT scaling rather than upsampling.
//   * This saves time if the upsampler gets to use 1:1 scaling.
//   * Note this code assumes that the supported DCT scalings are powers of 2.
//   */
//  for (ci = 0; ci < cinfo.num_components; ci++) {
//      compptr = cinfo.comp_info[ci];
//      int ssize = cinfo.min_DCT_scaled_size;
//      while (ssize < DCTSIZE &&
//          (compptr.h_samp_factor * ssize * 2 <= cinfo.max_h_samp_factor * cinfo.min_DCT_scaled_size) &&
//          (compptr.v_samp_factor * ssize * 2 <= cinfo.max_v_samp_factor * cinfo.min_DCT_scaled_size))
//      {
//          ssize = ssize * 2;
//      }
//      compptr.DCT_scaled_size = ssize;
//  }
//
//  /* Recompute downsampled dimensions of components;
//   * application needs to know these if using raw downsampled data.
//   */
//  for (ci = 0; ci < cinfo.num_components; ci++) {
//      compptr = cinfo.comp_info[ci];
//      /* Size in samples, after IDCT scaling */
//      compptr.downsampled_width = cast(int)
//          jdiv_round_up(cast(long) cinfo.image_width * cast(long) (compptr.h_samp_factor * compptr.DCT_scaled_size),
//              (cinfo.max_h_samp_factor * DCTSIZE));
//      compptr.downsampled_height = cast(int)
//          jdiv_round_up(cast(long) cinfo.image_height * cast(long) (compptr.v_samp_factor * compptr.DCT_scaled_size),
//              (cinfo.max_v_samp_factor * DCTSIZE));
//  }
//
//#else /* !IDCT_SCALING_SUPPORTED */

    /* Hardwire it to "no scaling" */
    cinfo.output_width = cinfo.image_width;
    cinfo.output_height = cinfo.image_height;
    /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
     * and has computed unscaled downsampled_width and downsampled_height.
     */

//#endif /* IDCT_SCALING_SUPPORTED */

    /* Report number of components in selected colorspace. */
    /* Probably this should be in the color conversion module... */
    switch (cinfo.out_color_space) {
        case JCS_GRAYSCALE:
            cinfo.out_color_components = 1;
            break;
        case JCS_RGB:
            if (RGB_PIXELSIZE !is 3) {
                cinfo.out_color_components = RGB_PIXELSIZE;
                break;
            }
            //FALLTHROUGH
        case JCS_YCbCr:
            cinfo.out_color_components = 3;
            break;
        case JCS_CMYK:
        case JCS_YCCK:
            cinfo.out_color_components = 4;
            break;
        default:            /* else must be same colorspace as in file */
            cinfo.out_color_components = cinfo.num_components;
            break;
    }
    cinfo.output_components = (cinfo.quantize_colors ? 1 : cinfo.out_color_components);

    /* See if upsampler will want to emit more than one row at a time */
    if (use_merged_upsample(cinfo))
        cinfo.rec_outbuf_height = cinfo.max_v_samp_factor;
    else
        cinfo.rec_outbuf_height = 1;
}

static bool use_merged_upsample (jpeg_decompress_struct cinfo) {
//#ifdef UPSAMPLE_MERGING_SUPPORTED
    /* Merging is the equivalent of plain box-filter upsampling */
    if (cinfo.do_fancy_upsampling || cinfo.CCIR601_sampling)
        return false;
    /* jdmerge.c only supports YCC=>RGB color conversion */
    if (cinfo.jpeg_color_space !is JCS_YCbCr || cinfo.num_components !is 3 ||
            cinfo.out_color_space !is JCS_RGB ||
            cinfo.out_color_components !is RGB_PIXELSIZE)
        return false;
    /* and it only handles 2h1v or 2h2v sampling ratios */
    if (cinfo.comp_info[0].h_samp_factor !is 2 ||
            cinfo.comp_info[1].h_samp_factor !is 1 ||
            cinfo.comp_info[2].h_samp_factor !is 1 ||
            cinfo.comp_info[0].v_samp_factor >  2 ||
            cinfo.comp_info[1].v_samp_factor !is 1 ||
            cinfo.comp_info[2].v_samp_factor !is 1)
        return false;
    /* furthermore, it doesn't work if we've scaled the IDCTs differently */
    if (cinfo.comp_info[0].DCT_scaled_size !is cinfo.min_DCT_scaled_size ||
            cinfo.comp_info[1].DCT_scaled_size !is cinfo.min_DCT_scaled_size ||
            cinfo.comp_info[2].DCT_scaled_size !is cinfo.min_DCT_scaled_size)
        return false;
    /* ??? also need to test for upsample-time rescaling, when & if supported */
    return true;            /* by golly, it'll work... */
//#else
//  return false;
//#endif
}

static void prepare_range_limit_table (jpeg_decompress_struct cinfo)
/* Allocate and fill in the sample_range_limit table */
{
    byte[] table;
    int i;

    table = new byte[5 * (MAXJSAMPLE+1) + CENTERJSAMPLE];
    int offset = (MAXJSAMPLE+1);    /* allow negative subscripts of simple table */
    cinfo.sample_range_limit_offset = offset;
    cinfo.sample_range_limit = table;
    /* First segment of "simple" table: limit[x] = 0 for x < 0 */
    /* Main part of "simple" table: limit[x] = x */
    for (i = 0; i <= MAXJSAMPLE; i++)
        table[i + offset] = cast(byte)i;
    offset += CENTERJSAMPLE;    /* Point to where post-IDCT table starts */
    /* End of simple table, rest of first half of post-IDCT table */
    for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
        table[i+offset] = cast(byte)MAXJSAMPLE;
    /* Second half of post-IDCT table */
    System.arraycopy(cinfo.sample_range_limit, cinfo.sample_range_limit_offset, table, offset + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE), CENTERJSAMPLE);
}

static void build_ycc_rgb_table (jpeg_decompress_struct cinfo) {
    jpeg_color_deconverter cconvert = cinfo.cconvert;
    int i;
    int x;
//  SHIFT_TEMPS

    cconvert.Cr_r_tab = new int[MAXJSAMPLE+1];
    cconvert.Cb_b_tab = new int[MAXJSAMPLE+1];
    cconvert.Cr_g_tab = new int[MAXJSAMPLE+1];
    cconvert.Cb_g_tab = new int[MAXJSAMPLE+1];

    for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
        /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
        /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
        /* Cr=>R value is nearest int to 1.40200 * x */
        cconvert.Cr_r_tab[i] = (cast(int)(1.40200f * (1<<SCALEBITS) + 0.5f) * x + ONE_HALF) >> SCALEBITS;
        /* Cb=>B value is nearest int to 1.77200 * x */
        cconvert.Cb_b_tab[i] = (cast(int)(1.77200f * (1<<SCALEBITS) + 0.5f) * x + ONE_HALF) >> SCALEBITS;
        /* Cr=>G value is scaled-up -0.71414 * x */
        cconvert.Cr_g_tab[i] = (cast(int)(- (0.71414f * (1<<SCALEBITS) + 0.5f)) * x);
        /* Cb=>G value is scaled-up -0.34414 * x */
        /* We also add in ONE_HALF so that need not do it in inner loop */
        cconvert.Cb_g_tab[i] = (cast(int)(- (0.34414f* (1<<SCALEBITS) + 0.5f)) * x + ONE_HALF);
    }
}

static void jinit_color_deconverter (jpeg_decompress_struct cinfo) {
    jpeg_color_deconverter cconvert = cinfo.cconvert = new jpeg_color_deconverter();
//  cconvert.start_pass = start_pass_dcolor;

    /* Make sure num_components agrees with jpeg_color_space */
    switch (cinfo.jpeg_color_space) {
        case JCS_GRAYSCALE:
            if (cinfo.num_components !is 1)
                error();
//              ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
            break;

        case JCS_RGB:
        case JCS_YCbCr:
            if (cinfo.num_components !is 3)
                error();
//              ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
            break;

        case JCS_CMYK:
        case JCS_YCCK:
            if (cinfo.num_components !is 4)
                error();
//              ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
            break;

        default:            /* JCS_UNKNOWN can be anything */
            if (cinfo.num_components < 1)
                error();
//              ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
            break;
    }

    /* Set out_color_components and conversion method based on requested space.
     * Also clear the component_needed flags for any unused components,
     * so that earlier pipeline stages can avoid useless computation.
     */

    int ci;
    switch (cinfo.out_color_space) {
        case JCS_GRAYSCALE:
            cinfo.out_color_components = 1;
            if (cinfo.jpeg_color_space is JCS_GRAYSCALE || cinfo.jpeg_color_space is JCS_YCbCr) {
                cconvert.color_convert = GRAYSCALE_CONVERT;
                /* For color.grayscale conversion, only the Y (0) component is needed */
                for (ci = 1; ci < cinfo.num_components; ci++)
                    cinfo.comp_info[ci].component_needed = false;
            } else
                error();
//              ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
            break;

        case JCS_RGB:
            cinfo.out_color_components = RGB_PIXELSIZE;
            if (cinfo.jpeg_color_space is JCS_YCbCr) {
                cconvert.color_convert = YCC_RGB_CONVERT;
                build_ycc_rgb_table(cinfo);
            } else if (cinfo.jpeg_color_space is JCS_GRAYSCALE) {
                cconvert.color_convert = GRAY_RGB_CONVERT;
            } else if (cinfo.jpeg_color_space is JCS_RGB && RGB_PIXELSIZE is 3) {
                cconvert.color_convert = NULL_CONVERT;
            } else
                error();
//              ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
                break;

        case JCS_CMYK:
            cinfo.out_color_components = 4;
            if (cinfo.jpeg_color_space is JCS_YCCK) {
                cconvert.color_convert = YCCK_CMYK_CONVERT;
                build_ycc_rgb_table(cinfo);
            } else if (cinfo.jpeg_color_space is JCS_CMYK) {
                cconvert.color_convert = NULL_CONVERT;
            } else
                error();
//              ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
            break;

        default:
            /* Permit null conversion to same output space */
            if (cinfo.out_color_space is cinfo.jpeg_color_space) {
                cinfo.out_color_components = cinfo.num_components;
                cconvert.color_convert = NULL_CONVERT;
            } else  /* unsupported non-null conversion */
                error();
//              ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
            break;
    }

    if (cinfo.quantize_colors)
        cinfo.output_components = 1; /* single colormapped output component */
    else
        cinfo.output_components = cinfo.out_color_components;
}

static void jinit_d_post_controller (jpeg_decompress_struct cinfo, bool need_full_buffer) {
    jpeg_d_post_controller post = cinfo.post = new jpeg_d_post_controller();
//  post.pub.start_pass = start_pass_dpost;
    post.whole_image = null;    /* flag for no virtual arrays */
    post.buffer = null;     /* flag for no strip buffer */

    /* Create the quantization buffer, if needed */
    if (cinfo.quantize_colors) {
        error(SWT.ERROR_NOT_IMPLEMENTED);
//      /* The buffer strip height is max_v_samp_factor, which is typically
//       * an efficient number of rows for upsampling to return.
//       * (In the presence of output rescaling, we might want to be smarter?)
//       */
//      post.strip_height = cinfo.max_v_samp_factor;
//      if (need_full_buffer) {
//          /* Two-pass color quantization: need full-image storage. */
//          /* We round up the number of rows to a multiple of the strip height. */
//#ifdef QUANT_2PASS_SUPPORTED
//          post.whole_image = (*cinfo.mem.request_virt_sarray)
//              ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
//              cinfo.output_width * cinfo.out_color_components,
//              (JDIMENSION) jround_up(cast(long) cinfo.output_height,
//              cast(long) post.strip_height),
//   post.strip_height);
//#else
//          ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
//#endif /* QUANT_2PASS_SUPPORTED */
//      } else {
//          /* One-pass color quantization: just make a strip buffer. */
//          post.buffer = (*cinfo.mem.alloc_sarray)
//              ((j_common_ptr) cinfo, JPOOL_IMAGE,
//              cinfo.output_width * cinfo.out_color_components,
//              post.strip_height);
//      }
    }
}

static void make_funny_pointers (jpeg_decompress_struct cinfo)
/* Create the funny pointer lists discussed in the comments above.
 * The actual workspace is already allocated (in main.buffer),
 * and the space for the pointer lists is allocated too.
 * This routine just fills in the curiously ordered lists.
 * This will be repeated at the beginning of each pass.
 */
{
    jpeg_d_main_controller main = cinfo.main;
    int ci, i, rgroup;
    int M = cinfo.min_DCT_scaled_size;
    jpeg_component_info compptr;
    byte[][] buf, xbuf0, xbuf1;

    for (ci = 0; ci < cinfo.num_components; ci++) {
        compptr = cinfo.comp_info[ci];
        rgroup = (compptr.v_samp_factor * compptr.DCT_scaled_size) /
            cinfo.min_DCT_scaled_size; /* height of a row group of component */
        xbuf0 = main.xbuffer[0][ci];
        int xbuf0_offset = main.xbuffer_offset[0][ci];
        xbuf1 = main.xbuffer[1][ci];
        int xbuf1_offset = main.xbuffer_offset[1][ci];
        /* First copy the workspace pointers as-is */
        buf = main.buffer[ci];
        for (i = 0; i < rgroup * (M + 2); i++) {
            xbuf0[i + xbuf0_offset] = xbuf1[i + xbuf1_offset] = buf[i];
        }
        /* In the second list, put the last four row groups in swapped order */
        for (i = 0; i < rgroup * 2; i++) {
            xbuf1[rgroup*(M-2) + i + xbuf1_offset] = buf[rgroup*M + i];
            xbuf1[rgroup*M + i + xbuf1_offset] = buf[rgroup*(M-2) + i];
        }
        /* The wraparound pointers at top and bottom will be filled later
         * (see set_wraparound_pointers, below).    Initially we want the "above"
         * pointers to duplicate the first actual data line.    This only needs
         * to happen in xbuffer[0].
         */
        for (i = 0; i < rgroup; i++) {
            xbuf0[i - rgroup + xbuf0_offset] = xbuf0[0 + xbuf0_offset];
        }
    }
}

static void alloc_funny_pointers (jpeg_decompress_struct cinfo)
/* Allocate space for the funny pointer lists.
 * This is done only once, not once per pass.
 */
{
    jpeg_d_main_controller main = cinfo.main;
    int ci, rgroup;
    int M = cinfo.min_DCT_scaled_size;
    jpeg_component_info compptr;
    byte[][] xbuf;

    /* Get top-level space for component array pointers.
     * We alloc both arrays with one call to save a few cycles.
     */
    main.xbuffer[0] = new byte[][][](cinfo.num_components);
    main.xbuffer[1] = new byte[][][](cinfo.num_components);
    main.xbuffer_offset[0] = new int[](cinfo.num_components);
    main.xbuffer_offset[1] = new int[](cinfo.num_components);

    for (ci = 0; ci < cinfo.num_components; ci++) {
        compptr = cinfo.comp_info[ci];
        rgroup = (compptr.v_samp_factor * compptr.DCT_scaled_size) / cinfo.min_DCT_scaled_size; /* height of a row group of component */
        /* Get space for pointer lists --- M+4 row groups in each list.
         * We alloc both pointer lists with one call to save a few cycles.
         */
        xbuf = new byte[][](2 * (rgroup * (M + 4)));
        int offset = rgroup;
        main.xbuffer_offset[0][ci] = offset;
        main.xbuffer[0][ci] = xbuf;
        offset += rgroup * (M + 4);
        main.xbuffer_offset[1][ci] = offset;
        main.xbuffer[1][ci] = xbuf;
    }
}


static void jinit_d_main_controller (jpeg_decompress_struct cinfo, bool need_full_buffer) {
    int ci, rgroup, ngroups;
    jpeg_component_info compptr;

    jpeg_d_main_controller main = cinfo.main = new jpeg_d_main_controller();
//  main.pub.start_pass = start_pass_main;

    if (need_full_buffer)       /* shouldn't happen */
        error();
//      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

    /* Allocate the workspace.
     * ngroups is the number of row groups we need.
     */
    if (cinfo.upsample.need_context_rows) {
        if (cinfo.min_DCT_scaled_size < 2) /* unsupported, see comments above */
            error();
//          ERREXIT(cinfo, JERR_NOTIMPL);
        alloc_funny_pointers(cinfo); /* Alloc space for xbuffer[] lists */
        ngroups = cinfo.min_DCT_scaled_size + 2;
    } else {
        ngroups = cinfo.min_DCT_scaled_size;
    }

    for (ci = 0; ci < cinfo.num_components; ci++) {
        compptr = cinfo.comp_info[ci];
        rgroup = (compptr.v_samp_factor * compptr.DCT_scaled_size) / cinfo.min_DCT_scaled_size; /* height of a row group of component */
        main.buffer[ci] = new byte[][]( rgroup * ngroups, compptr.width_in_blocks * compptr.DCT_scaled_size );
    }
}

static long jround_up (long a, long b)
/* Compute a rounded up to next multiple of b, ie, ceil(a/b)*b */
/* Assumes a >= 0, b > 0 */
{
    a += b - 1L;
    return a - (a % b);
}

static void jinit_upsampler (jpeg_decompress_struct cinfo) {
    int ci;
    jpeg_component_info compptr;
    bool need_buffer, do_fancy;
    int h_in_group, v_in_group, h_out_group, v_out_group;

    jpeg_upsampler upsample = new jpeg_upsampler();
    cinfo.upsample = upsample;
//  upsample.start_pass = start_pass_upsample;
//  upsample.upsample = sep_upsample;
    upsample.need_context_rows = false; /* until we find out differently */

    if (cinfo.CCIR601_sampling) /* this isn't supported */
        error();
//      ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);

    /* jdmainct.c doesn't support context rows when min_DCT_scaled_size = 1,
     * so don't ask for it.
     */
    do_fancy = cinfo.do_fancy_upsampling && cinfo.min_DCT_scaled_size > 1;

    /* Verify we can handle the sampling factors, select per-component methods,
     * and create storage as needed.
     */
    for (ci = 0; ci < cinfo.num_components; ci++) {
        compptr = cinfo.comp_info[ci];
        /* Compute size of an "input group" after IDCT scaling. This many samples
         * are to be converted to max_h_samp_factor * max_v_samp_factor pixels.
         */
        h_in_group = (compptr.h_samp_factor * compptr.DCT_scaled_size) /
         cinfo.min_DCT_scaled_size;
        v_in_group = (compptr.v_samp_factor * compptr.DCT_scaled_size) /
         cinfo.min_DCT_scaled_size;
        h_out_group = cinfo.max_h_samp_factor;
        v_out_group = cinfo.max_v_samp_factor;
        upsample.rowgroup_height[ci] = v_in_group; /* save for use later */
        need_buffer = true;
        if (! compptr.component_needed) {
            /* Don't bother to upsample an uninteresting component. */
            upsample.methods[ci] = NOOP_UPSAMPLE;
            need_buffer = false;
        } else if (h_in_group is h_out_group && v_in_group is v_out_group) {
            /* Fullsize components can be processed without any work. */
            upsample.methods[ci] = FULLSIZE_UPSAMPLE;
            need_buffer = false;
        } else if (h_in_group * 2 is h_out_group && v_in_group is v_out_group) {
            /* Special cases for 2h1v upsampling */
            if (do_fancy && compptr.downsampled_width > 2)
                upsample.methods[ci] = H2V1_FANCY_UPSAMPLE;
            else
                upsample.methods[ci] = H2V1_UPSAMPLE;
        } else if (h_in_group * 2 is h_out_group && v_in_group * 2 is v_out_group) {
            /* Special cases for 2h2v upsampling */
            if (do_fancy && compptr.downsampled_width > 2) {
                upsample.methods[ci] = H2V2_FANCY_UPSAMPLE;
                upsample.need_context_rows = true;
            } else
                upsample.methods[ci] = H2V2_UPSAMPLE;
        } else if ((h_out_group % h_in_group) is 0 && (v_out_group % v_in_group) is 0) {
            /* Generic integral-factors upsampling method */
            upsample.methods[ci] = INT_UPSAMPLE;
            upsample.h_expand[ci] = cast(byte) (h_out_group / h_in_group);
            upsample.v_expand[ci] = cast(byte) (v_out_group / v_in_group);
        } else
            error();
//          ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
        if (need_buffer) {
            upsample.color_buf[ci] = new byte[][]( cinfo.max_v_samp_factor,
                         cast(int) jround_up(cinfo.output_width, cinfo.max_h_samp_factor));
        }
    }
}

static void jinit_phuff_decoder (jpeg_decompress_struct cinfo) {
    int[][] coef_bit_ptr;
    int ci, i;

    cinfo.entropy = new phuff_entropy_decoder();
//  entropy.pub.start_pass = start_pass_phuff_decoder;

    /* Create progression status table */
    cinfo.coef_bits = new int[][]( cinfo.num_components, DCTSIZE2 );
    coef_bit_ptr = cinfo.coef_bits;
    for (ci = 0; ci < cinfo.num_components; ci++)
        for (i = 0; i < DCTSIZE2; i++)
            coef_bit_ptr[ci][i] = -1;
}


static void jinit_huff_decoder (jpeg_decompress_struct cinfo) {

    cinfo.entropy = new huff_entropy_decoder();
//  entropy.pub.start_pass = start_pass_huff_decoder;
//  entropy.pub.decode_mcu = decode_mcu;

}

static void jinit_inverse_dct (jpeg_decompress_struct cinfo) {
    int ci;
    jpeg_component_info compptr;

    jpeg_inverse_dct idct = cinfo.idct = new jpeg_inverse_dct();
//  idct.pub.start_pass = start_pass;

    for (ci = 0; ci < cinfo.num_components; ci++) {
        compptr = cinfo.comp_info[ci];
        /* Allocate and pre-zero a multiplier table for each component */
        compptr.dct_table = new int[DCTSIZE2];
        /* Mark multiplier table not yet set up for any method */
        idct.cur_method[ci] = -1;
    }
}

static const int CONST_BITS = 13;
static const int PASS1_BITS = 2;
static const int RANGE_MASK =(MAXJSAMPLE * 4 + 3);
static void jpeg_idct_islow (jpeg_decompress_struct cinfo, jpeg_component_info compptr,
    short[] coef_block,
    byte[][] output_buf, int output_buf_offset, int output_col)
{
    int tmp0, tmp1, tmp2, tmp3;
    int tmp10, tmp11, tmp12, tmp13;
    int z1, z2, z3, z4, z5;
    short[] inptr;
    int[] quantptr;
    int[] wsptr;
    byte[] outptr;
    byte[] range_limit = cinfo.sample_range_limit;
    int range_limit_offset = cinfo.sample_range_limit_offset + CENTERJSAMPLE;
    int ctr;
    int[] workspace = cinfo.workspace;  /* buffers data between passes */
//  SHIFT_TEMPS

    /* Pass 1: process columns from input, store into work array. */
    /* Note results are scaled up by sqrt(8) compared to a true IDCT; */
    /* furthermore, we scale the results by 2**PASS1_BITS. */

    inptr = coef_block;
    quantptr = compptr.dct_table;
    wsptr = workspace;
    int inptr_offset = 0, quantptr_offset = 0, wsptr_offset = 0;
    for (ctr = DCTSIZE; ctr > 0; ctr--) {
        /* Due to quantization, we will usually find that many of the input
         * coefficients are zero, especially the AC terms.  We can exploit this
         * by short-circuiting the IDCT calculation for any column in which all
         * the AC terms are zero.   In that case each output is equal to the
         * DC coefficient (with scale factor as needed).
         * With typical images and quantization tables, half or more of the
         * column DCT calculations can be simplified this way.
         */

        if (inptr[DCTSIZE*1+inptr_offset] is 0 && inptr[DCTSIZE*2+inptr_offset] is 0 &&
            inptr[DCTSIZE*3+inptr_offset] is 0 && inptr[DCTSIZE*4+inptr_offset] is 0 &&
            inptr[DCTSIZE*5+inptr_offset] is 0 && inptr[DCTSIZE*6+inptr_offset] is 0 &&
            inptr[DCTSIZE*7+inptr_offset] is 0)
        {
            /* AC terms all zero */
            int dcval = ((inptr[DCTSIZE*0+inptr_offset]) * quantptr[DCTSIZE*0+quantptr_offset]) << PASS1_BITS;

            wsptr[DCTSIZE*0+wsptr_offset] = dcval;
            wsptr[DCTSIZE*1+wsptr_offset] = dcval;
            wsptr[DCTSIZE*2+wsptr_offset] = dcval;
            wsptr[DCTSIZE*3+wsptr_offset] = dcval;
            wsptr[DCTSIZE*4+wsptr_offset] = dcval;
            wsptr[DCTSIZE*5+wsptr_offset] = dcval;
            wsptr[DCTSIZE*6+wsptr_offset] = dcval;
            wsptr[DCTSIZE*7+wsptr_offset] = dcval;

            inptr_offset++;         /* advance pointers to next column */
            quantptr_offset++;
            wsptr_offset++;
            continue;
        }

        /* Even part: reverse the even part of the forward DCT. */
        /* The rotator is sqrt(2)*c(-6). */

        z2 = ((inptr[DCTSIZE*2+inptr_offset]) * quantptr[DCTSIZE*2+quantptr_offset]);
        z3 = ((inptr[DCTSIZE*6+inptr_offset]) * quantptr[DCTSIZE*6+quantptr_offset]);

        z1 = ((z2 + z3) * 4433/*FIX_0_541196100*/);
        tmp2 = z1 + (z3 * - 15137/*FIX_1_847759065*/);
        tmp3 = z1 + (z2 * 6270/*FIX_0_765366865*/);

        z2 = ((inptr[DCTSIZE*0+inptr_offset]) * quantptr[DCTSIZE*0+quantptr_offset]);
        z3 = ((inptr[DCTSIZE*4+inptr_offset]) * quantptr[DCTSIZE*4+quantptr_offset]);

        tmp0 = (z2 + z3) << CONST_BITS;
        tmp1 = (z2 - z3) << CONST_BITS;

        tmp10 = tmp0 + tmp3;
        tmp13 = tmp0 - tmp3;
        tmp11 = tmp1 + tmp2;
        tmp12 = tmp1 - tmp2;

        /* Odd part per figure 8; the matrix is unitary and hence its
         * transpose is its inverse.    i0..i3 are y7,y5,y3,y1 respectively.
         */

        tmp0 = ((inptr[DCTSIZE*7+inptr_offset]) * quantptr[DCTSIZE*7+quantptr_offset]);
        tmp1 = ((inptr[DCTSIZE*5+inptr_offset]) * quantptr[DCTSIZE*5+quantptr_offset]);
        tmp2 = ((inptr[DCTSIZE*3+inptr_offset]) * quantptr[DCTSIZE*3+quantptr_offset]);
        tmp3 = ((inptr[DCTSIZE*1+inptr_offset]) * quantptr[DCTSIZE*1+quantptr_offset]);

        z1 = tmp0 + tmp3;
        z2 = tmp1 + tmp2;
        z3 = tmp0 + tmp2;
        z4 = tmp1 + tmp3;
        z5 = ((z3 + z4) * 9633/*FIX_1_175875602*/); /* sqrt(2) * c3 */

        tmp0 = (tmp0 * 2446/*FIX_0_298631336*/); /* sqrt(2) * (-c1+c3+c5-c7) */
        tmp1 = (tmp1 * 16819/*FIX_2_053119869*/); /* sqrt(2) * ( c1+c3-c5+c7) */
        tmp2 = (tmp2 * 25172/*FIX_3_072711026*/); /* sqrt(2) * ( c1+c3+c5-c7) */
        tmp3 = (tmp3 * 12299/*FIX_1_501321110*/); /* sqrt(2) * ( c1+c3-c5-c7) */
        z1 = (z1 * - 7373/*FIX_0_899976223*/); /* sqrt(2) * (c7-c3) */
        z2 = (z2 * - 20995/*FIX_2_562915447*/); /* sqrt(2) * (-c1-c3) */
        z3 = (z3 * - 16069/*FIX_1_961570560*/); /* sqrt(2) * (-c3-c5) */
        z4 = (z4 * - 3196/*FIX_0_390180644*/); /* sqrt(2) * (c5-c3) */

        z3 += z5;
        z4 += z5;

        tmp0 += z1 + z3;
        tmp1 += z2 + z4;
        tmp2 += z2 + z3;
        tmp3 += z1 + z4;

        /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */

//      #define DESCALE(x,n)    RIGHT_SHIFT((x) + (ONE << ((n)-1)), n)
        wsptr[DCTSIZE*0+wsptr_offset] = (((tmp10 + tmp3) + (1 << ((CONST_BITS-PASS1_BITS)-1))) >> (CONST_BITS-PASS1_BITS));
        wsptr[DCTSIZE*7+wsptr_offset] = (((tmp10 - tmp3) + (1 << ((CONST_BITS-PASS1_BITS)-1))) >> (CONST_BITS-PASS1_BITS));
        wsptr[DCTSIZE*1+wsptr_offset] = (((tmp11 + tmp2) + (1 << ((CONST_BITS-PASS1_BITS)-1))) >> (CONST_BITS-PASS1_BITS));
        wsptr[DCTSIZE*6+wsptr_offset] = (((tmp11 - tmp2) + (1 << ((CONST_BITS-PASS1_BITS)-1))) >> (CONST_BITS-PASS1_BITS));
        wsptr[DCTSIZE*2+wsptr_offset] = (((tmp12 + tmp1) + (1 << ((CONST_BITS-PASS1_BITS)-1))) >> (CONST_BITS-PASS1_BITS));
        wsptr[DCTSIZE*5+wsptr_offset] = (((tmp12 - tmp1) + (1 << ((CONST_BITS-PASS1_BITS)-1))) >> (CONST_BITS-PASS1_BITS));
        wsptr[DCTSIZE*3+wsptr_offset] = (((tmp13 + tmp0) + (1 << ((CONST_BITS-PASS1_BITS)-1))) >> (CONST_BITS-PASS1_BITS));
        wsptr[DCTSIZE*4+wsptr_offset] = (((tmp13 - tmp0) + (1 << ((CONST_BITS-PASS1_BITS)-1))) >> (CONST_BITS-PASS1_BITS));

        inptr_offset++;         /* advance pointers to next column */
        quantptr_offset++;
        wsptr_offset++;
    }


    /* Pass 2: process rows from work array, store into output array. */
    /* Note that we must descale the results by a factor of 8 is 2**3, */
    /* and also undo the PASS1_BITS scaling. */

    int outptr_offset = 0;
    wsptr = workspace;
    wsptr_offset =0;
    for (ctr = 0; ctr < DCTSIZE; ctr++) {
        outptr = output_buf[ctr+output_buf_offset];
        outptr_offset = output_col;
        /* Rows of zeroes can be exploited in the same way as we did with columns.
         * However, the column calculation has created many nonzero AC terms, so
         * the simplification applies less often (typically 5% to 10% of the time).
         * On machines with very fast multiplication, it's possible that the
         * test takes more time than it's worth.    In that case this section
         * may be commented out.
         */

//#ifndef NO_ZERO_ROW_TEST
        if (wsptr[1+wsptr_offset] is 0 && wsptr[2+wsptr_offset] is 0 && wsptr[3+wsptr_offset] is 0 && wsptr[4+wsptr_offset] is 0 &&
            wsptr[5+wsptr_offset] is 0 && wsptr[6+wsptr_offset] is 0 && wsptr[7+wsptr_offset] is 0)
        {
            /* AC terms all zero */
//          #define DESCALE(x,n)    RIGHT_SHIFT((x) + (ONE << ((n)-1)), n)
            byte dcval = range_limit[range_limit_offset + ((((wsptr[0+wsptr_offset]) + (1 << ((PASS1_BITS+3)-1))) >> PASS1_BITS+3)
                    & RANGE_MASK)];

            outptr[0+outptr_offset] = dcval;
            outptr[1+outptr_offset] = dcval;
            outptr[2+outptr_offset] = dcval;
            outptr[3+outptr_offset] = dcval;
            outptr[4+outptr_offset] = dcval;
            outptr[5+outptr_offset] = dcval;
            outptr[6+outptr_offset] = dcval;
            outptr[7+outptr_offset] = dcval;

            wsptr_offset += DCTSIZE;        /* advance pointer to next row */
            continue;
        }
//#endif

        /* Even part: reverse the even part of the forward DCT. */
        /* The rotator is sqrt(2)*c(-6). */

        z2 = wsptr[2+wsptr_offset];
        z3 = wsptr[6+wsptr_offset];

        z1 = ((z2 + z3) * 4433/*FIX_0_541196100*/);
        tmp2 = z1 + (z3 * - 15137/*FIX_1_847759065*/);
        tmp3 = z1 + (z2 * 6270/*FIX_0_765366865*/);

        tmp0 = (wsptr[0+wsptr_offset] + wsptr[4+wsptr_offset]) << CONST_BITS;
        tmp1 = (wsptr[0+wsptr_offset] - wsptr[4+wsptr_offset]) << CONST_BITS;

        tmp10 = tmp0 + tmp3;
        tmp13 = tmp0 - tmp3;
        tmp11 = tmp1 + tmp2;
        tmp12 = tmp1 - tmp2;

        /* Odd part per figure 8; the matrix is unitary and hence its
         * transpose is its inverse.    i0..i3 are y7,y5,y3,y1 respectively.
         */

        tmp0 = wsptr[7+wsptr_offset];
        tmp1 = wsptr[5+wsptr_offset];
        tmp2 = wsptr[3+wsptr_offset];
        tmp3 = wsptr[1+wsptr_offset];

        z1 = tmp0 + tmp3;
        z2 = tmp1 + tmp2;
        z3 = tmp0 + tmp2;
        z4 = tmp1 + tmp3;
        z5 = ((z3 + z4) * 9633/*FIX_1_175875602*/); /* sqrt(2) * c3 */

        tmp0 = (tmp0 * 2446/*FIX_0_298631336*/); /* sqrt(2) * (-c1+c3+c5-c7) */
        tmp1 = (tmp1 * 16819/*FIX_2_053119869*/); /* sqrt(2) * ( c1+c3-c5+c7) */
        tmp2 = (tmp2 * 25172/*FIX_3_072711026*/); /* sqrt(2) * ( c1+c3+c5-c7) */
        tmp3 = (tmp3 * 12299/*FIX_1_501321110*/); /* sqrt(2) * ( c1+c3-c5-c7) */
        z1 = (z1 * - 7373/*FIX_0_899976223*/); /* sqrt(2) * (c7-c3) */
        z2 = (z2 * - 20995/*FIX_2_562915447*/); /* sqrt(2) * (-c1-c3) */
        z3 = (z3 * - 16069/*FIX_1_961570560*/); /* sqrt(2) * (-c3-c5) */
        z4 = (z4 * - 3196/*FIX_0_390180644*/); /* sqrt(2) * (c5-c3) */

        z3 += z5;
        z4 += z5;

        tmp0 += z1 + z3;
        tmp1 += z2 + z4;
        tmp2 += z2 + z3;
        tmp3 += z1 + z4;

        /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */


//      #define DESCALE(x,n)    RIGHT_SHIFT((x) + (ONE << ((n)-1)), n)
        outptr[0+outptr_offset] = range_limit[range_limit_offset + ((((tmp10 + tmp3) + (1 << ((CONST_BITS+PASS1_BITS+3)-1))) >>
                        CONST_BITS+PASS1_BITS+3)
                    & RANGE_MASK)];
        outptr[7+outptr_offset] = range_limit[range_limit_offset + ((((tmp10 - tmp3) + (1 << ((CONST_BITS+PASS1_BITS+3)-1))) >>
                                    CONST_BITS+PASS1_BITS+3)
                    & RANGE_MASK)];
        outptr[1+outptr_offset] = range_limit[range_limit_offset + ((((tmp11 + tmp2) + (1 << ((CONST_BITS+PASS1_BITS+3)-1))) >>
                                    CONST_BITS+PASS1_BITS+3)
                    & RANGE_MASK)];
        outptr[6+outptr_offset] = range_limit[range_limit_offset + ((((tmp11 - tmp2) + (1 << ((CONST_BITS+PASS1_BITS+3)-1))) >>
                                    CONST_BITS+PASS1_BITS+3)
                    & RANGE_MASK)];
        outptr[2+outptr_offset] = range_limit[range_limit_offset + ((((tmp12 + tmp1) + (1 << ((CONST_BITS+PASS1_BITS+3)-1))) >>
                                    CONST_BITS+PASS1_BITS+3)
                    & RANGE_MASK)];
        outptr[5+outptr_offset] = range_limit[range_limit_offset + ((((tmp12 - tmp1) + (1 << ((CONST_BITS+PASS1_BITS+3)-1))) >>
                                    CONST_BITS+PASS1_BITS+3)
                    & RANGE_MASK)];
        outptr[3+outptr_offset] = range_limit[range_limit_offset + ((((tmp13 + tmp0) + (1 << ((CONST_BITS+PASS1_BITS+3)-1))) >>
                                    CONST_BITS+PASS1_BITS+3)
                    & RANGE_MASK)];
        outptr[4+outptr_offset] = range_limit[range_limit_offset + ((((tmp13 - tmp0) + (1 << ((CONST_BITS+PASS1_BITS+3)-1))) >>
                                    CONST_BITS+PASS1_BITS+3)
                    & RANGE_MASK)];

        wsptr_offset += DCTSIZE;        /* advance pointer to next row */
    }
}

static void upsample (jpeg_decompress_struct cinfo,
    byte[][][] input_buf, int[] input_buf_offset, int[] in_row_group_ctr,
    int in_row_groups_avail,
    byte[][] output_buf, int[] out_row_ctr,
    int out_rows_avail)
{
    sep_upsample(cinfo, input_buf, input_buf_offset, in_row_group_ctr, in_row_groups_avail, output_buf, out_row_ctr, out_rows_avail);
}

static bool smoothing_ok (jpeg_decompress_struct cinfo) {
    jpeg_d_coef_controller coef = cinfo.coef;
    bool smoothing_useful = false;
    int ci, coefi;
    jpeg_component_info compptr;
    JQUANT_TBL qtable;
    int[] coef_bits;
    int[] coef_bits_latch;

    if (! cinfo.progressive_mode || cinfo.coef_bits is null)
        return false;

    /* Allocate latch area if not already done */
    if (coef.coef_bits_latch is null)
        coef.coef_bits_latch = new int[cinfo.num_components * SAVED_COEFS];
    coef_bits_latch = coef.coef_bits_latch;
    int coef_bits_latch_offset = 0;

    for (ci = 0; ci < cinfo.num_components; ci++) {
        compptr = cinfo.comp_info[ci];
        /* All components' quantization values must already be latched. */
        if ((qtable = compptr.quant_table) is null)
            return false;
        /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */
        if (qtable.quantval[0] is 0 ||
            qtable.quantval[Q01_POS] is 0 ||
            qtable.quantval[Q10_POS] is 0 ||
            qtable.quantval[Q20_POS] is 0 ||
            qtable.quantval[Q11_POS] is 0 ||
            qtable.quantval[Q02_POS] is 0)
                return false;
        /* DC values must be at least partly known for all components. */
        coef_bits = cinfo.coef_bits[ci];
        if (coef_bits[0] < 0)
            return false;
        /* Block smoothing is helpful if some AC coefficients remain inaccurate. */
        for (coefi = 1; coefi <= 5; coefi++) {
            coef_bits_latch[coefi+coef_bits_latch_offset] = coef_bits[coefi];
            if (coef_bits[coefi] !is 0)
                smoothing_useful = true;
        }
        coef_bits_latch_offset += SAVED_COEFS;
    }

    return smoothing_useful;
}

static void master_selection (jpeg_decompress_struct cinfo) {
    jpeg_decomp_master master = cinfo.master;
    bool use_c_buffer;
    long samplesperrow;
    int jd_samplesperrow;

    /* Initialize dimensions and other stuff */
    jpeg_calc_output_dimensions(cinfo);
    prepare_range_limit_table(cinfo);

    /* Width of an output scanline must be representable as JDIMENSION. */
    samplesperrow = cast(long) cinfo.output_width * cast(long) cinfo.out_color_components;
    jd_samplesperrow = cast(int) samplesperrow;
    if ( jd_samplesperrow !is samplesperrow)
        error();
//      ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);

    /* Initialize my private state */
    master.pass_number = 0;
    master.using_merged_upsample = use_merged_upsample(cinfo);

    /* Color quantizer selection */
    master.quantizer_1pass = null;
    master.quantizer_2pass = null;
    /* No mode changes if not using buffered-image mode. */
    if (! cinfo.quantize_colors || ! cinfo.buffered_image) {
        cinfo.enable_1pass_quant = false;
        cinfo.enable_external_quant = false;
        cinfo.enable_2pass_quant = false;
    }
    if (cinfo.quantize_colors) {
        error(SWT.ERROR_NOT_IMPLEMENTED);
//      if (cinfo.raw_data_out)
//          ERREXIT(cinfo, JERR_NOTIMPL);
//      /* 2-pass quantizer only works in 3-component color space. */
//      if (cinfo.out_color_components !is 3) {
//          cinfo.enable_1pass_quant = true;
//          cinfo.enable_external_quant = false;
//          cinfo.enable_2pass_quant = false;
//          cinfo.colormap = null;
//      } else if (cinfo.colormap !is null) {
//          cinfo.enable_external_quant = true;
//      } else if (cinfo.two_pass_quantize) {
//          cinfo.enable_2pass_quant = true;
//      } else {
//          cinfo.enable_1pass_quant = true;
//      }
//
//      if (cinfo.enable_1pass_quant) {
//#ifdef QUANT_1PASS_SUPPORTED
//          jinit_1pass_quantizer(cinfo);
//          master.quantizer_1pass = cinfo.cquantize;
//#else
//          ERREXIT(cinfo, JERR_NOT_COMPILED);
//#endif
//      }
//
//      /* We use the 2-pass code to map to external colormaps. */
//      if (cinfo.enable_2pass_quant || cinfo.enable_external_quant) {
//#ifdef QUANT_2PASS_SUPPORTED
//          jinit_2pass_quantizer(cinfo);
//          master.quantizer_2pass = cinfo.cquantize;
//#else
//          ERREXIT(cinfo, JERR_NOT_COMPILED);
//#endif
//      }
//      /* If both quantizers are initialized, the 2-pass one is left active;
//       * this is necessary for starting with quantization to an external map.
//       */
    }

    /* Post-processing: in particular, color conversion first */
    if (! cinfo.raw_data_out) {
        if (master.using_merged_upsample) {
//#ifdef UPSAMPLE_MERGING_SUPPORTED
//          jinit_merged_upsampler(cinfo); /* does color conversion too */
//#else
            error();
//          ERREXIT(cinfo, JERR_NOT_COMPILED);
//#endif
        } else {
            jinit_color_deconverter(cinfo);
            jinit_upsampler(cinfo);
        }
        jinit_d_post_controller(cinfo, cinfo.enable_2pass_quant);
    }
    /* Inverse DCT */
    jinit_inverse_dct(cinfo);
    /* Entropy decoding: either Huffman or arithmetic coding. */
    if (cinfo.arith_code) {
        error();
//      ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
    } else {
        if (cinfo.progressive_mode) {
//#ifdef D_PROGRESSIVE_SUPPORTED
            jinit_phuff_decoder(cinfo);
//#else
//          ERREXIT(cinfo, JERR_NOT_COMPILED);
//#endif
        } else
            jinit_huff_decoder(cinfo);
    }

    /* Initialize principal buffer controllers. */
    use_c_buffer = cinfo.inputctl.has_multiple_scans || cinfo.buffered_image;
    jinit_d_coef_controller(cinfo, use_c_buffer);

    if (! cinfo.raw_data_out)
        jinit_d_main_controller(cinfo, false /* never need full buffer here */);

    /* Initialize input side of decompressor to consume first scan. */
    start_input_pass (cinfo);

//#ifdef D_MULTISCAN_FILES_SUPPORTED
    /* If jpeg_start_decompress will read the whole file, initialize
     * progress monitoring appropriately.   The input step is counted
     * as one pass.
     */
//  if (cinfo.progress !is null && ! cinfo.buffered_image &&
//          cinfo.inputctl.has_multiple_scans) {
//      int nscans;
//      /* Estimate number of scans to set pass_limit. */
//      if (cinfo.progressive_mode) {
//          /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
//          nscans = 2 + 3 * cinfo.num_components;
//      } else {
//          /* For a nonprogressive multiscan file, estimate 1 scan per component. */
//          nscans = cinfo.num_components;
//      }
//      cinfo.progress.pass_counter = 0L;
//      cinfo.progress.pass_limit = cast(long) cinfo.total_iMCU_rows * nscans;
//      cinfo.progress.completed_passes = 0;
//      cinfo.progress.total_passes = (cinfo.enable_2pass_quant ? 3 : 2);
//      /* Count the input pass as done */
//      master.pass_number++;
//  }
//#endif /* D_MULTISCAN_FILES_SUPPORTED */
}

static void jinit_master_decompress (jpeg_decompress_struct cinfo) {
    jpeg_decomp_master master = new jpeg_decomp_master();
    cinfo.master = master;
//  master.prepare_for_output_pass = prepare_for_output_pass;
//  master.finish_output_pass = finish_output_pass;

    master.is_dummy_pass = false;

    master_selection(cinfo);
}

static void
jcopy_sample_rows (byte[][] input_array, int source_row,
           byte[][] output_array, int dest_row,
           int num_rows, int num_cols)
/* Copy some rows of samples from one place to another.
 * num_rows rows are copied from input_array[source_row++]
 * to output_array[dest_row++]; these areas may overlap for duplication.
 * The source and destination arrays must be at least as wide as num_cols.
 */
{
  byte[] inptr, outptr;
  int count = num_cols;
  int row;

  int input_array_offset = source_row;
  int output_array_offset = dest_row;

  for (row = num_rows; row > 0; row--) {
    inptr = input_array[input_array_offset++];
    outptr = output_array[output_array_offset++];
    System.arraycopy(inptr, 0, outptr, 0, count);
  }
}

static bool jpeg_start_decompress (jpeg_decompress_struct cinfo) {
    if (cinfo.global_state is DSTATE_READY) {
        /* First call: initialize master control, select active modules */
        jinit_master_decompress(cinfo);
        if (cinfo.buffered_image) {
            /* No more work here; expecting jpeg_start_output next */
            cinfo.global_state = DSTATE_BUFIMAGE;
            return true;
        }
        cinfo.global_state = DSTATE_PRELOAD;
    }
    if (cinfo.global_state is DSTATE_PRELOAD) {
        /* If file has multiple scans, absorb them all into the coef buffer */
        if (cinfo.inputctl.has_multiple_scans) {
//#ifdef D_MULTISCAN_FILES_SUPPORTED
            for (;;) {
                int retcode;
                /* Call progress monitor hook if present */
//              if (cinfo.progress !is null)
//                  (*cinfo.progress.progress_monitor) ((j_common_ptr) cinfo);
                /* Absorb some more input */
                retcode = consume_input (cinfo);
                if (retcode is JPEG_SUSPENDED)
                    return false;
                if (retcode is JPEG_REACHED_EOI)
                    break;
                /* Advance progress counter if appropriate */
//              if (cinfo.progress !is null && (retcode is JPEG_ROW_COMPLETED || retcode is JPEG_REACHED_SOS)) {
//                  if (++cinfo.progress.pass_counter >= cinfo.progress.pass_limit) {
//                      /* jdmaster underestimated number of scans; ratchet up one scan */
//                      cinfo.progress.pass_limit += cast(long) cinfo.total_iMCU_rows;
//                  }
//              }
            }
//#else
//          ERREXIT(cinfo, JERR_NOT_COMPILED);
//#endif /* D_MULTISCAN_FILES_SUPPORTED */
        }
        cinfo.output_scan_number = cinfo.input_scan_number;
    } else if (cinfo.global_state !is DSTATE_PRESCAN)
        error();
//      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo.global_state);
    /* Perform any dummy output passes, and set up for the final pass */
    return output_pass_setup(cinfo);
}

static void prepare_for_output_pass (jpeg_decompress_struct cinfo) {
    jpeg_decomp_master master = cinfo.master;

    if (master.is_dummy_pass) {
//#ifdef QUANT_2PASS_SUPPORTED
//      /* Final pass of 2-pass quantization */
//      master.pub.is_dummy_pass = FALSE;
//      (*cinfo.cquantize.start_pass) (cinfo, FALSE);
//      (*cinfo.post.start_pass) (cinfo, JBUF_CRANK_DEST);
//      (*cinfo.main.start_pass) (cinfo, JBUF_CRANK_DEST);
//#else
        error(SWT.ERROR_NOT_IMPLEMENTED);
//      ERREXIT(cinfo, JERR_NOT_COMPILED);
//#endif /* QUANT_2PASS_SUPPORTED */
    } else {
        if (cinfo.quantize_colors && cinfo.colormap is null) {
            /* Select new quantization method */
            if (cinfo.two_pass_quantize && cinfo.enable_2pass_quant) {
                cinfo.cquantize = master.quantizer_2pass;
                master.is_dummy_pass = true;
            } else if (cinfo.enable_1pass_quant) {
                cinfo.cquantize = master.quantizer_1pass;
            } else {
                error();
//  ERREXIT(cinfo, JERR_MODE_CHANGE);
            }
        }
        cinfo.idct.start_pass (cinfo);
        start_output_pass (cinfo);
        if (! cinfo.raw_data_out) {
            if (! master.using_merged_upsample)
                cinfo.cconvert.start_pass (cinfo);
            cinfo.upsample.start_pass (cinfo);
            if (cinfo.quantize_colors)
                cinfo.cquantize.start_pass (cinfo, master.is_dummy_pass);
            cinfo.post.start_pass (cinfo, (master.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
            cinfo.main.start_pass (cinfo, JBUF_PASS_THRU);
        }
    }

//  /* Set up progress monitor's pass info if present */
//  if (cinfo.progress !is NULL) {
//      cinfo.progress.completed_passes = master.pass_number;
//      cinfo.progress.total_passes = master.pass_number +
//                      (master.pub.is_dummy_pass ? 2 : 1);
//      /* In buffered-image mode, we assume one more output pass if EOI not
//       * yet reached, but no more passes if EOI has been reached.
//       */
//      if (cinfo.buffered_image && ! cinfo.inputctl.eoi_reached) {
//          cinfo.progress.total_passes += (cinfo.enable_2pass_quant ? 2 : 1);
//      }
//  }
}


static bool jpeg_resync_to_restart (jpeg_decompress_struct cinfo, int desired) {
    int marker = cinfo.unread_marker;
    int action = 1;

    /* Always put up a warning. */
//  WARNMS2(cinfo, JWRN_MUST_RESYNC, marker, desired);

    /* Outer loop handles repeated decision after scanning forward. */
    for (;;) {
        if (marker < M_SOF0)
            action = 2;     /* invalid marker */
        else if (marker < M_RST0 || marker > M_RST7)
            action = 3;     /* valid non-restart marker */
        else {
            if (marker is (M_RST0 + ((desired+1) & 7)) || marker is ( M_RST0 + ((desired+2) & 7)))
                action = 3;     /* one of the next two expected restarts */
            else if (marker is (M_RST0 + ((desired-1) & 7)) || marker is ( M_RST0 + ((desired-2) & 7)))
                action = 2;     /* a prior restart, so advance */
            else
                action = 1;     /* desired restart or too far away */
        }
//      TRACEMS2(cinfo, 4, JTRC_RECOVERY_ACTION, marker, action);
        switch (action) {
            case 1:
                /* Discard marker and let entropy decoder resume processing. */
                cinfo.unread_marker = 0;
                return true;
            case 2:
                /* Scan to the next marker, and repeat the decision loop. */
                if (! next_marker(cinfo))
                    return false;
                marker = cinfo.unread_marker;
                break;
            case 3:
                /* Return without advancing past this marker. */
                /* Entropy decoder will be forced to process an empty segment. */
                return true;
            default:
        }
    } /* end loop */
}

static bool read_restart_marker (jpeg_decompress_struct cinfo) {
    /* Obtain a marker unless we already did. */
    /* Note that next_marker will complain if it skips any data. */
    if (cinfo.unread_marker is 0) {
        if (! next_marker(cinfo))
            return false;
    }

    if (cinfo.unread_marker is (M_RST0 + cinfo.marker.next_restart_num)) {
        /* Normal case --- swallow the marker and let entropy decoder continue */
//      TRACEMS1(cinfo, 3, JTRC_RST, cinfo.marker.next_restart_num);
        cinfo.unread_marker = 0;
    } else {
        /* Uh-oh, the restart markers have been messed up. */
        /* Let the data source manager determine how to resync. */
        if (! jpeg_resync_to_restart (cinfo, cinfo.marker.next_restart_num))
            return false;
    }

    /* Update next-restart state */
    cinfo.marker.next_restart_num = (cinfo.marker.next_restart_num + 1) & 7;

    return true;
}

static bool jpeg_fill_bit_buffer (bitread_working_state state, int get_buffer, int bits_left, int nbits)
/* Load up the bit buffer to a depth of at least nbits */
{
    /* Copy heavily used state fields into locals (hopefully registers) */
    byte[] buffer = state.buffer;
    int bytes_in_buffer = state.bytes_in_buffer;
    int bytes_offset = state.bytes_offset;
    jpeg_decompress_struct cinfo = state.cinfo;

    /* Attempt to load at least MIN_GET_BITS bits into get_buffer. */
    /* (It is assumed that no request will be for more than that many bits.) */
    /* We fail to do so only if we hit a marker or are forced to suspend. */

    if (cinfo.unread_marker is 0) { /* cannot advance past a marker */
        while (bits_left < MIN_GET_BITS) {
            int c;

            /* Attempt to read a byte */
            if (bytes_offset is bytes_in_buffer) {
                if (! fill_input_buffer (cinfo))
                    return false;
                buffer = cinfo.buffer;
                bytes_in_buffer = cinfo.bytes_in_buffer;
                bytes_offset = cinfo.bytes_offset;
            }
            c = buffer[bytes_offset++] & 0xFF;

            /* If it's 0xFF, check and discard stuffed zero byte */
            if (c is 0xFF) {
                /* Loop here to discard any padding FF's on terminating marker,
                 * so that we can save a valid unread_marker value. NOTE: we will
                 * accept multiple FF's followed by a 0 as meaning a single FF data
                 * byte.    This data pattern is not valid according to the standard.
                 */
                do {
                    if (bytes_offset is bytes_in_buffer) {
                        if (! fill_input_buffer (cinfo))
                            return false;
                        buffer = cinfo.buffer;
                        bytes_in_buffer = cinfo.bytes_in_buffer;
                        bytes_offset = cinfo.bytes_offset;
                    }
                    c = buffer[bytes_offset++] & 0xFF;
                } while (c is 0xFF);

                if (c is 0) {
                    /* Found FF/00, which represents an FF data byte */
                    c = 0xFF;
                } else {
                    /* Oops, it's actually a marker indicating end of compressed data.
                     * Save the marker code for later use.
                     * Fine point: it might appear that we should save the marker into
                     * bitread working state, not straight into permanent state.    But
                     * once we have hit a marker, we cannot need to suspend within the
                     * current MCU, because we will read no more bytes from the data
                     * source.  So it is OK to update permanent state right away.
                     */
                    cinfo.unread_marker = c;
                    /* See if we need to insert some fake zero bits. */
//                  goto no_more_bytes;
                    if (nbits > bits_left) {
                        /* Uh-oh.   Report corrupted data to user and stuff zeroes into
                         * the data stream, so that we can produce some kind of image.
                         * We use a nonvolatile flag to ensure that only one warning message
                         * appears per data segment.
                         */
                        if (! cinfo.entropy.insufficient_data) {
//                          WARNMS(cinfo, JWRN_HIT_MARKER);
                            cinfo.entropy.insufficient_data = true;
                        }
                    /* Fill the buffer with zero bits */
                        get_buffer <<= MIN_GET_BITS - bits_left;
                        bits_left = MIN_GET_BITS;
                    }

                    /* Unload the local registers */
                    state.buffer = buffer;
                    state.bytes_in_buffer = bytes_in_buffer;
                    state.bytes_offset = bytes_offset;
                    state.get_buffer = get_buffer;
                    state.bits_left = bits_left;

                    return true;

                }
            }

            /* OK, load c into get_buffer */
            get_buffer = (get_buffer << 8) | c;
            bits_left += 8;
        } /* end while */
    } else {
//      no_more_bytes:
        /* We get here if we've read the marker that terminates the compressed
         * data segment.    There should be enough bits in the buffer register
         * to satisfy the request; if so, no problem.
         */
        if (nbits > bits_left) {
            /* Uh-oh.   Report corrupted data to user and stuff zeroes into
             * the data stream, so that we can produce some kind of image.
             * We use a nonvolatile flag to ensure that only one warning message
             * appears per data segment.
             */
            if (! cinfo.entropy.insufficient_data) {
//              WARNMS(cinfo, JWRN_HIT_MARKER);
                cinfo.entropy.insufficient_data = true;
            }
            /* Fill the buffer with zero bits */
            get_buffer <<= MIN_GET_BITS - bits_left;
            bits_left = MIN_GET_BITS;
        }
    }

    /* Unload the local registers */
    state.buffer = buffer;
    state.bytes_in_buffer = bytes_in_buffer;
    state.bytes_offset = bytes_offset;
    state.get_buffer = get_buffer;
    state.bits_left = bits_left;

    return true;
}

static int jpeg_huff_decode (bitread_working_state state, int get_buffer, int bits_left, d_derived_tbl htbl, int min_bits) {
    int l = min_bits;
    int code;

    /* HUFF_DECODE has determined that the code is at least min_bits */
    /* bits long, so fetch that many bits in one swoop. */

//  CHECK_BIT_BUFFER(*state, l, return -1);
    {
    if (bits_left < (l)) {
        if (! jpeg_fill_bit_buffer(state,get_buffer,bits_left,l)) {
            return -1;
        }
        get_buffer = state.get_buffer; bits_left = state.bits_left;
    }
    }
//  code = GET_BITS(l);
    code = (( (get_buffer >> (bits_left -= (l)))) & ((1<<(l))-1));

    /* Collect the rest of the Huffman code one bit at a time. */
    /* This is per Figure F.16 in the JPEG spec. */

    while (code > htbl.maxcode[l]) {
        code <<= 1;
//      CHECK_BIT_BUFFER(*state, 1, return -1);
        {
        if (bits_left < (1)) {
            if (! jpeg_fill_bit_buffer(state,get_buffer,bits_left,1)) {
                return -1;
            }
            get_buffer = state.get_buffer; bits_left = state.bits_left;
        }
        }
//      code |= GET_BITS(1);
        code |= (( (get_buffer >> (bits_left -= (1)))) & ((1<<(1))-1));
        l++;
    }

    /* Unload the local registers */
    state.get_buffer = get_buffer;
    state.bits_left = bits_left;

    /* With garbage input we may reach the sentinel value l = 17. */

    if (l > 16) {
//      WARNMS(state.cinfo, JWRN_HUFF_BAD_CODE);
        return 0;           /* fake a zero as the safest result */
    }

    return htbl.pub.huffval[ (code + htbl.valoffset[l]) ] & 0xFF;
}

static int decompress_onepass (jpeg_decompress_struct cinfo, byte[][][] output_buf, int[] output_buf_offset) {
    jpeg_d_coef_controller coef = cinfo.coef;
    int MCU_col_num;    /* index of current MCU within row */
    int last_MCU_col = cinfo.MCUs_per_row - 1;
    int last_iMCU_row = cinfo.total_iMCU_rows - 1;
    int blkn, ci, xindex, yindex, yoffset, useful_width;
    byte[][] output_ptr;
    int start_col, output_col;
    jpeg_component_info compptr;
//  inverse_DCT_method_ptr inverse_DCT;

    /* Loop to process as much as one whole iMCU row */
    for (yoffset = coef.MCU_vert_offset; yoffset < coef.MCU_rows_per_iMCU_row; yoffset++) {
        for (MCU_col_num = coef.MCU_ctr; MCU_col_num <= last_MCU_col; MCU_col_num++) {
            /* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */
            for (int i = 0; i < cinfo.blocks_in_MCU; i++) {
                short[] blk = coef.MCU_buffer[i];
                for (int j = 0; j < blk.length; j++) {
                    blk[j] = 0;
                }
            }
            if (! cinfo.entropy.decode_mcu (cinfo, coef.MCU_buffer)) {
                /* Suspension forced; update state counters and exit */
                coef.MCU_vert_offset = yoffset;
                coef.MCU_ctr = MCU_col_num;
                return JPEG_SUSPENDED;
            }
            /* Determine where data should go in output_buf and do the IDCT thing.
             * We skip dummy blocks at the right and bottom edges (but blkn gets
             * incremented past them!). Note the inner loop relies on having
             * allocated the MCU_buffer[] blocks sequentially.
             */
            blkn = 0;           /* index of current DCT block within MCU */
            for (ci = 0; ci < cinfo.comps_in_scan; ci++) {
                compptr = cinfo.cur_comp_info[ci];
                /* Don't bother to IDCT an uninteresting component. */
                if (! compptr.component_needed) {
                    blkn += compptr.MCU_blocks;
                    continue;
                }
//              inverse_DCT = cinfo.idct.inverse_DCT[compptr.component_index];
                useful_width = (MCU_col_num < last_MCU_col) ? compptr.MCU_width : compptr.last_col_width;
                output_ptr = output_buf[compptr.component_index];
                int output_ptr_offset = output_buf_offset[compptr.component_index] + yoffset * compptr.DCT_scaled_size;
                start_col = MCU_col_num * compptr.MCU_sample_width;
                for (yindex = 0; yindex < compptr.MCU_height; yindex++) {
                    if (cinfo.input_iMCU_row < last_iMCU_row || yoffset+yindex < compptr.last_row_height) {
                        output_col = start_col;
                        for (xindex = 0; xindex < useful_width; xindex++) {
                            jpeg_idct_islow(cinfo, compptr, coef.MCU_buffer[blkn+xindex], output_ptr, output_ptr_offset, output_col);
                            output_col += compptr.DCT_scaled_size;
                        }
                    }
                    blkn += compptr.MCU_width;
                    output_ptr_offset += compptr.DCT_scaled_size;
                }
            }
        }
        /* Completed an MCU row, but perhaps not an iMCU row */
        coef.MCU_ctr = 0;
    }
    /* Completed the iMCU row, advance counters for next one */
    cinfo.output_iMCU_row++;
    if (++(cinfo.input_iMCU_row) < cinfo.total_iMCU_rows) {
        coef.start_iMCU_row(cinfo);
        return JPEG_ROW_COMPLETED;
    }
    /* Completed the scan */
    finish_input_pass (cinfo);
    return JPEG_SCAN_COMPLETED;
}

static int decompress_smooth_data (jpeg_decompress_struct cinfo, byte[][][] output_buf, int[] output_buf_offset) {
    jpeg_d_coef_controller coef = cinfo.coef;
    int last_iMCU_row = cinfo.total_iMCU_rows - 1;
    int block_num, last_block_column;
    int ci, block_row, block_rows, access_rows;
    short[][][] buffer;
    short[][] buffer_ptr, prev_block_row, next_block_row;
    byte[][] output_ptr;
    int output_col;
    jpeg_component_info compptr;
//  inverse_DCT_method_ptr inverse_DCT;
    bool first_row, last_row;
    short[] workspace = coef.workspace;
    if (workspace is null) workspace = coef.workspace = new short[DCTSIZE2];
    int[] coef_bits;
    JQUANT_TBL quanttbl;
    int Q00,Q01,Q02,Q10,Q11,Q20, num;
    int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9;
    int Al, pred;

    /* Force some input to be done if we are getting ahead of the input. */
    while (cinfo.input_scan_number <= cinfo.output_scan_number && ! cinfo.inputctl.eoi_reached) {
        if (cinfo.input_scan_number is cinfo.output_scan_number) {
            /* If input is working on current scan, we ordinarily want it to
             * have completed the current row.  But if input scan is DC,
             * we want it to keep one row ahead so that next block row's DC
             * values are up to date.
             */
            int delta = (cinfo.Ss is 0) ? 1 : 0;
            if (cinfo.input_iMCU_row > cinfo.output_iMCU_row+delta)
                break;
        }
        if (consume_input(cinfo) is JPEG_SUSPENDED)
            return JPEG_SUSPENDED;
    }

    /* OK, output from the virtual arrays. */
    for (ci = 0; ci < cinfo.num_components; ci++) {
        compptr = cinfo.comp_info[ci];
        /* Don't bother to IDCT an uninteresting component. */
        if (! compptr.component_needed)
            continue;
        /* Count non-dummy DCT block rows in this iMCU row. */
        if (cinfo.output_iMCU_row < last_iMCU_row) {
            block_rows = compptr.v_samp_factor;
            access_rows = block_rows * 2; /* this and next iMCU row */
            last_row = false;
        } else {
            /* NB: can't use last_row_height here; it is input-side-dependent! */
            block_rows = (compptr.height_in_blocks % compptr.v_samp_factor);
            if (block_rows is 0) block_rows = compptr.v_samp_factor;
            access_rows = block_rows; /* this iMCU row only */
            last_row = true;
        }
        /* Align the virtual buffer for this component. */
        int buffer_offset;
        if (cinfo.output_iMCU_row > 0) {
            access_rows += compptr.v_samp_factor; /* prior iMCU row too */
            buffer = coef.whole_image[ci];
            buffer_offset = (cinfo.output_iMCU_row - 1) * compptr.v_samp_factor;
            buffer_offset += compptr.v_samp_factor; /* point to current iMCU row */
            first_row = false;
        } else {
            buffer = coef.whole_image[ci];
            buffer_offset = 0;
            first_row = true;
        }
        /* Fetch component-dependent info */
        coef_bits = coef.coef_bits_latch;
        int coef_offset = (ci * SAVED_COEFS);
        quanttbl = compptr.quant_table;
        Q00 = quanttbl.quantval[0];
        Q01 = quanttbl.quantval[Q01_POS];
        Q10 = quanttbl.quantval[Q10_POS];
        Q20 = quanttbl.quantval[Q20_POS];
        Q11 = quanttbl.quantval[Q11_POS];
        Q02 = quanttbl.quantval[Q02_POS];
//      inverse_DCT = cinfo.idct.inverse_DCT[ci];
        output_ptr = output_buf[ci];
        int output_ptr_offset = output_buf_offset[ci];
        /* Loop over all DCT blocks to be processed. */
        for (block_row = 0; block_row < block_rows; block_row++) {
            buffer_ptr = buffer[block_row+buffer_offset];
            int buffer_ptr_offset = 0, prev_block_row_offset = 0, next_block_row_offset = 0;
            if (first_row && block_row is 0) {
                prev_block_row = buffer_ptr;
                prev_block_row_offset = buffer_ptr_offset;
            } else {
                prev_block_row = buffer[block_row-1+buffer_offset];
                prev_block_row_offset = 0;
            }
            if (last_row && block_row is block_rows-1) {
                next_block_row = buffer_ptr;
                next_block_row_offset = buffer_ptr_offset;
            } else {
                next_block_row = buffer[block_row+1+buffer_offset];
                next_block_row_offset = 0;
            }
            /* We fetch the surrounding DC values using a sliding-register approach.
             * Initialize all nine here so as to do the right thing on narrow pics.
             */
            DC1 = DC2 = DC3 = prev_block_row[0+prev_block_row_offset][0];
            DC4 = DC5 = DC6 = buffer_ptr[0+buffer_ptr_offset][0];
            DC7 = DC8 = DC9 = next_block_row[0+next_block_row_offset][0];
            output_col = 0;
            last_block_column = compptr.width_in_blocks - 1;
            for (block_num = 0; block_num <= last_block_column; block_num++) {
                /* Fetch current DCT block into workspace so we can modify it. */
//              jcopy_block_row(buffer_ptr, workspace, 1);
                System.arraycopy(buffer_ptr[buffer_ptr_offset], 0, workspace, 0, workspace.length);
                /* Update DC values */
                if (block_num < last_block_column) {
                    DC3 = prev_block_row[1+prev_block_row_offset][0];
                    DC6 = buffer_ptr[1+buffer_ptr_offset][0];
                    DC9 = next_block_row[1+next_block_row_offset][0];
                }
                /* Compute coefficient estimates per K.8.
                 * An estimate is applied only if coefficient is still zero,
                 * and is not known to be fully accurate.
                 */
                /* AC01 */
                if ((Al=coef_bits[1+coef_offset]) !is 0 && workspace[1] is 0) {
                    num = 36 * Q00 * (DC4 - DC6);
                    if (num >= 0) {
                        pred = (((Q01<<7) + num) / (Q01<<8));
                        if (Al > 0 && pred >= (1<<Al))
                            pred = (1<<Al)-1;
                    } else {
                        pred = (((Q01<<7) - num) / (Q01<<8));
                        if (Al > 0 && pred >= (1<<Al))
                            pred = (1<<Al)-1;
                        pred = -pred;
                    }
                    workspace[1] = cast(short) pred;
                }
                /* AC10 */
                if ((Al=coef_bits[2+coef_offset]) !is 0 && workspace[8] is 0) {
                    num = 36 * Q00 * (DC2 - DC8);
                    if (num >= 0) {
                        pred = (((Q10<<7) + num) / (Q10<<8));
                        if (Al > 0 && pred >= (1<<Al))
                            pred = (1<<Al)-1;
                    } else {
                        pred = (((Q10<<7) - num) / (Q10<<8));
                        if (Al > 0 && pred >= (1<<Al))
                            pred = (1<<Al)-1;
                        pred = -pred;
                    }
                    workspace[8] = cast(short) pred;
                }
                /* AC20 */
                if ((Al=coef_bits[3+coef_offset]) !is 0 && workspace[16] is 0) {
                    num = 9 * Q00 * (DC2 + DC8 - 2*DC5);
                    if (num >= 0) {
                        pred = (((Q20<<7) + num) / (Q20<<8));
                        if (Al > 0 && pred >= (1<<Al))
                            pred = (1<<Al)-1;
                    } else {
                        pred = (((Q20<<7) - num) / (Q20<<8));
                        if (Al > 0 && pred >= (1<<Al))
                            pred = (1<<Al)-1;
                        pred = -pred;
                    }
                    workspace[16] = cast(short) pred;
                }
                /* AC11 */
                if ((Al=coef_bits[4+coef_offset]) !is 0 && workspace[9] is 0) {
                    num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
                    if (num >= 0) {
                        pred = (((Q11<<7) + num) / (Q11<<8));
                        if (Al > 0 && pred >= (1<<Al))
                            pred = (1<<Al)-1;
                    } else {
                        pred = (((Q11<<7) - num) / (Q11<<8));
                        if (Al > 0 && pred >= (1<<Al))
                            pred = (1<<Al)-1;
                        pred = -pred;
                    }
                    workspace[9] = cast(short) pred;
                }
                /* AC02 */
                if ((Al=coef_bits[5+coef_offset]) !is 0 && workspace[2] is 0) {
                    num = 9 * Q00 * (DC4 + DC6 - 2*DC5);
                    if (num >= 0) {
                        pred = (((Q02<<7) + num) / (Q02<<8));
                        if (Al > 0 && pred >= (1<<Al))
                            pred = (1<<Al)-1;
                    } else {
                        pred = (((Q02<<7) - num) / (Q02<<8));
                        if (Al > 0 && pred >= (1<<Al))
                            pred = (1<<Al)-1;
                        pred = -pred;
                    }
                    workspace[2] = cast(short) pred;
                }
                /* OK, do the IDCT */
                jpeg_idct_islow(cinfo, compptr, workspace, output_ptr, output_ptr_offset, output_col);
                /* Advance for next column */
                DC1 = DC2; DC2 = DC3;
                DC4 = DC5; DC5 = DC6;
                DC7 = DC8; DC8 = DC9;
                buffer_ptr_offset++; prev_block_row_offset++; next_block_row_offset++;
                output_col += compptr.DCT_scaled_size;
            }
            output_ptr_offset += compptr.DCT_scaled_size;
        }
    }

    if (++(cinfo.output_iMCU_row) < cinfo.total_iMCU_rows)
        return JPEG_ROW_COMPLETED;
    return JPEG_SCAN_COMPLETED;
}

static int decompress_data (jpeg_decompress_struct cinfo, byte[][][] output_buf, int[] output_buf_offset) {
    jpeg_d_coef_controller coef = cinfo.coef;
    int last_iMCU_row = cinfo.total_iMCU_rows - 1;
    int block_num;
    int ci, block_row, block_rows;
    short[][][] buffer;
    short[][] buffer_ptr;
    byte[][] output_ptr;
    int output_col;
    jpeg_component_info compptr;
//  inverse_DCT_method_ptr inverse_DCT;

    /* Force some input to be done if we are getting ahead of the input. */
    while (cinfo.input_scan_number < cinfo.output_scan_number ||
     (cinfo.input_scan_number is cinfo.output_scan_number &&
        cinfo.input_iMCU_row <= cinfo.output_iMCU_row))
    {
        if (consume_input(cinfo) is JPEG_SUSPENDED)
            return JPEG_SUSPENDED;
    }

    /* OK, output from the virtual arrays. */
    for (ci = 0; ci < cinfo.num_components; ci++) {
        compptr = cinfo.comp_info[ci];
        /* Don't bother to IDCT an uninteresting component. */
        if (! compptr.component_needed)
            continue;
        /* Align the virtual buffer for this component. */
        buffer = coef.whole_image[ci];
        int buffer_offset = cinfo.output_iMCU_row * compptr.v_samp_factor;
        /* Count non-dummy DCT block rows in this iMCU row. */
        if (cinfo.output_iMCU_row < last_iMCU_row)
            block_rows = compptr.v_samp_factor;
        else {
            /* NB: can't use last_row_height here; it is input-side-dependent! */
            block_rows = (compptr.height_in_blocks % compptr.v_samp_factor);
            if (block_rows is 0) block_rows = compptr.v_samp_factor;
        }
//      inverse_DCT = cinfo.idct.inverse_DCT[ci];
        output_ptr = output_buf[ci];
        int output_ptr_offset = output_buf_offset[ci];
        /* Loop over all DCT blocks to be processed. */
        for (block_row = 0; block_row < block_rows; block_row++) {
            buffer_ptr = buffer[block_row+buffer_offset];
            int buffer_ptr_offset = 0;
            output_col = 0;
            for (block_num = 0; block_num < compptr.width_in_blocks; block_num++) {
                jpeg_idct_islow(cinfo, compptr, buffer_ptr[buffer_ptr_offset], output_ptr, output_ptr_offset, output_col);

                buffer_ptr_offset++;
                output_col += compptr.DCT_scaled_size;
            }
            output_ptr_offset += compptr.DCT_scaled_size;
        }
    }

    if (++(cinfo.output_iMCU_row) < cinfo.total_iMCU_rows)
        return JPEG_ROW_COMPLETED;
    return JPEG_SCAN_COMPLETED;
}

static void post_process_data (jpeg_decompress_struct cinfo,
                byte[][][] input_buf, int[] input_buf_offset, int[] in_row_group_ctr,
                int in_row_groups_avail,
                byte[][] output_buf, int[] out_row_ctr,
                int out_rows_avail)
{
    upsample(cinfo, input_buf, input_buf_offset, in_row_group_ctr, in_row_groups_avail, output_buf, out_row_ctr, out_rows_avail);
}

static void set_bottom_pointers (jpeg_decompress_struct cinfo)
/* Change the pointer lists to duplicate the last sample row at the bottom
 * of the image.    whichptr indicates which xbuffer holds the final iMCU row.
 * Also sets rowgroups_avail to indicate number of nondummy row groups in row.
 */
{
    jpeg_d_main_controller main = cinfo.main;
    int ci, i, rgroup, iMCUheight, rows_left;
    jpeg_component_info compptr;
    byte[][] xbuf;

    for (ci = 0; ci < cinfo.num_components; ci++) {
        compptr = cinfo.comp_info[ci];
        /* Count sample rows in one iMCU row and in one row group */
        iMCUheight = compptr.v_samp_factor * compptr.DCT_scaled_size;
        rgroup = iMCUheight / cinfo.min_DCT_scaled_size;
        /* Count nondummy sample rows remaining for this component */
        rows_left = (compptr.downsampled_height % iMCUheight);
        if (rows_left is 0) rows_left = iMCUheight;
        /* Count nondummy row groups.   Should get same answer for each component,
         * so we need only do it once.
         */
        if (ci is 0) {
            main.rowgroups_avail = ((rows_left-1) / rgroup + 1);
        }
        /* Duplicate the last real sample row rgroup*2 times; this pads out the
         * last partial rowgroup and ensures at least one full rowgroup of context.
         */
        xbuf = main.xbuffer[main.whichptr][ci];
        int xbuf_offset = main.xbuffer_offset[main.whichptr][ci];
        for (i = 0; i < rgroup * 2; i++) {
            xbuf[rows_left + i + xbuf_offset] = xbuf[rows_left-1 + xbuf_offset];
        }
    }
}

static void set_wraparound_pointers (jpeg_decompress_struct cinfo)
/* Set up the "wraparound" pointers at top and bottom of the pointer lists.
 * This changes the pointer list state from top-of-image to the normal state.
 */
{
    jpeg_d_main_controller main = cinfo.main;
    int ci, i, rgroup;
    int M = cinfo.min_DCT_scaled_size;
    jpeg_component_info compptr;
    byte[][] xbuf0, xbuf1;

    for (ci = 0; ci < cinfo.num_components; ci++) {
        compptr = cinfo.comp_info[ci];
        rgroup = (compptr.v_samp_factor * compptr.DCT_scaled_size) / cinfo.min_DCT_scaled_size; /* height of a row group of component */
        xbuf0 = main.xbuffer[0][ci];
        int xbuf0_offset = main.xbuffer_offset[0][ci];
        xbuf1 = main.xbuffer[1][ci];
        int xbuf1_offset = main.xbuffer_offset[1][ci];
        for (i = 0; i < rgroup; i++) {
            xbuf0[i - rgroup + xbuf0_offset] = xbuf0[rgroup*(M+1) + i + xbuf0_offset];
            xbuf1[i - rgroup + xbuf1_offset] = xbuf1[rgroup*(M+1) + i + xbuf1_offset];
            xbuf0[rgroup*(M+2) + i + xbuf0_offset] = xbuf0[i + xbuf0_offset];
            xbuf1[rgroup*(M+2) + i + xbuf1_offset] = xbuf1[i + xbuf1_offset];
        }
    }
}

static void process_data_crank_post (jpeg_decompress_struct cinfo,
    byte[][] output_buf, int[] out_row_ctr,
    int out_rows_avail)
{
    error();
}

static void process_data_context_main (jpeg_decompress_struct cinfo,
    byte[][] output_buf, int[] out_row_ctr,
    int out_rows_avail)
{
    jpeg_d_main_controller main = cinfo.main;

    /* Read input data if we haven't filled the main buffer yet */
    if (! main.buffer_full) {
        int result;
        switch (cinfo.coef.decompress_data) {
            case DECOMPRESS_DATA:
                result = decompress_data(cinfo, main.xbuffer[main.whichptr], main.xbuffer_offset[main.whichptr]);
                break;
            case DECOMPRESS_SMOOTH_DATA:
                result = decompress_smooth_data(cinfo, main.xbuffer[main.whichptr], main.xbuffer_offset[main.whichptr]);
                break;
            case DECOMPRESS_ONEPASS:
                result = decompress_onepass(cinfo, main.xbuffer[main.whichptr], main.xbuffer_offset[main.whichptr]);
                break;
            default: result = 0;
        }
        if (result is 0)
            return;         /* suspension forced, can do nothing more */
        main.buffer_full = true;    /* OK, we have an iMCU row to work with */
        main.iMCU_row_ctr++;    /* count rows received */
    }

    /* Postprocessor typically will not swallow all the input data it is handed
     * in one call (due to filling the output buffer first).    Must be prepared
     * to exit and restart. This switch lets us keep track of how far we got.
     * Note that each case falls through to the next on successful completion.
     */
    switch (main.context_state) {
        case CTX_POSTPONED_ROW:
            /* Call postprocessor using previously set pointers for postponed row */
            post_process_data (cinfo, main.xbuffer[main.whichptr], main.xbuffer_offset[main.whichptr], main.rowgroup_ctr, main.rowgroups_avail, output_buf, out_row_ctr, out_rows_avail);
            if (main.rowgroup_ctr[0] < main.rowgroups_avail)
                return;         /* Need to suspend */
            main.context_state = CTX_PREPARE_FOR_IMCU;
            if (out_row_ctr[0] >= out_rows_avail)
                return;         /* Postprocessor exactly filled output buf */
            /*FALLTHROUGH*/
        case CTX_PREPARE_FOR_IMCU:
            /* Prepare to process first M-1 row groups of this iMCU row */
            main.rowgroup_ctr[0] = 0;
            main.rowgroups_avail = (cinfo.min_DCT_scaled_size - 1);
            /* Check for bottom of image: if so, tweak pointers to "duplicate"
             * the last sample row, and adjust rowgroups_avail to ignore padding rows.
             */
            if (main.iMCU_row_ctr is cinfo.total_iMCU_rows)
                set_bottom_pointers(cinfo);
            main.context_state = CTX_PROCESS_IMCU;
            /*FALLTHROUGH*/
        case CTX_PROCESS_IMCU:
            /* Call postprocessor using previously set pointers */
            post_process_data (cinfo, main.xbuffer[main.whichptr], main.xbuffer_offset[main.whichptr], main.rowgroup_ctr, main.rowgroups_avail, output_buf, out_row_ctr, out_rows_avail);
            if (main.rowgroup_ctr[0] < main.rowgroups_avail)
                return;         /* Need to suspend */
            /* After the first iMCU, change wraparound pointers to normal state */
            if (main.iMCU_row_ctr is 1)
                set_wraparound_pointers(cinfo);
            /* Prepare to load new iMCU row using other xbuffer list */
            main.whichptr ^= 1; /* 0=>1 or 1=>0 */
            main.buffer_full = false;
            /* Still need to process last row group of this iMCU row, */
            /* which is saved at index M+1 of the other xbuffer */
            main.rowgroup_ctr[0] = (cinfo.min_DCT_scaled_size + 1);
            main.rowgroups_avail =  (cinfo.min_DCT_scaled_size + 2);
            main.context_state = CTX_POSTPONED_ROW;
        default:
    }
}

static void process_data_simple_main (jpeg_decompress_struct cinfo, byte[][] output_buf, int[] out_row_ctr, int out_rows_avail) {
    jpeg_d_main_controller main = cinfo.main;
    int rowgroups_avail;

    /* Read input data if we haven't filled the main buffer yet */
    if (! main.buffer_full) {
        int result;
        switch (cinfo.coef.decompress_data) {
            case DECOMPRESS_DATA:
                result = decompress_data(cinfo, main.buffer, main.buffer_offset);
                break;
            case DECOMPRESS_SMOOTH_DATA:
                result = decompress_smooth_data(cinfo, main.buffer, main.buffer_offset);
                break;
            case DECOMPRESS_ONEPASS:
                result = decompress_onepass(cinfo, main.buffer, main.buffer_offset);
                break;
            default: result = 0;
        }
        if (result is 0)
            return;         /* suspension forced, can do nothing more */
        main.buffer_full = true;    /* OK, we have an iMCU row to work with */
    }

    /* There are always min_DCT_scaled_size row groups in an iMCU row. */
    rowgroups_avail = cinfo.min_DCT_scaled_size;
    /* Note: at the bottom of the image, we may pass extra garbage row groups
     * to the postprocessor.    The postprocessor has to check for bottom
     * of image anyway (at row resolution), so no point in us doing it too.
     */

    /* Feed the postprocessor */
    post_process_data (cinfo, main.buffer, main.buffer_offset, main.rowgroup_ctr, rowgroups_avail, output_buf, out_row_ctr, out_rows_avail);

    /* Has postprocessor consumed all the data yet? If so, mark buffer empty */
    if (main.rowgroup_ctr[0] >= rowgroups_avail) {
        main.buffer_full = false;
        main.rowgroup_ctr[0] = 0;
    }
}

static int jpeg_read_scanlines (jpeg_decompress_struct cinfo, byte[][] scanlines, int max_lines) {

    if (cinfo.global_state !is DSTATE_SCANNING)
        error();
//      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo.global_state);
    if (cinfo.output_scanline >= cinfo.output_height) {
//      WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
        return 0;
    }

    /* Call progress monitor hook if present */
//  if (cinfo.progress !is NULL) {
//      cinfo.progress.pass_counter = cast(long) cinfo.output_scanline;
//      cinfo.progress.pass_limit = cast(long) cinfo.output_height;
//      (*cinfo.progress.progress_monitor) ((j_common_ptr) cinfo);
//  }

    /* Process some data */
    cinfo.row_ctr[0] = 0;
    switch (cinfo.main.process_data) {
        case PROCESS_DATA_SIMPLE_MAIN:
            process_data_simple_main (cinfo, scanlines, cinfo.row_ctr, max_lines);
            break;
        case PROCESS_DATA_CONTEXT_MAIN:
            process_data_context_main (cinfo, scanlines, cinfo.row_ctr, max_lines);
            break;
        case PROCESS_DATA_CRANK_POST:
            process_data_crank_post (cinfo, scanlines, cinfo.row_ctr, max_lines);
            break;
        default: error();
    }
    cinfo.output_scanline += cinfo.row_ctr[0];
    return cinfo.row_ctr[0];
}


static bool output_pass_setup (jpeg_decompress_struct cinfo) {
    if (cinfo.global_state !is DSTATE_PRESCAN) {
        /* First call: do pass setup */
        prepare_for_output_pass (cinfo);
        cinfo.output_scanline = 0;
        cinfo.global_state = DSTATE_PRESCAN;
    }
    /* Loop over any required dummy passes */
    while (cinfo.master.is_dummy_pass) {
        error();
//#ifdef QUANT_2PASS_SUPPORTED
//      /* Crank through the dummy pass */
//      while (cinfo.output_scanline < cinfo.output_height) {
//          JDIMENSION last_scanline;
//          /* Call progress monitor hook if present */
//          if (cinfo.progress !is NULL) {
//  cinfo.progress.pass_counter = cast(long) cinfo.output_scanline;
//  cinfo.progress.pass_limit = cast(long) cinfo.output_height;
//  (*cinfo.progress.progress_monitor) ((j_common_ptr) cinfo);
//          }
//          /* Process some data */
//          last_scanline = cinfo.output_scanline;
//          (*cinfo.main.process_data) (cinfo, (JSAMPARRAY) NULL,
//                      &cinfo.output_scanline, (JDIMENSION) 0);
//          if (cinfo.output_scanline is last_scanline)
//  return FALSE;       /* No progress made, must suspend */
//      }
//      /* Finish up dummy pass, and set up for another one */
//      (*cinfo.master.finish_output_pass) (cinfo);
//      (*cinfo.master.prepare_for_output_pass) (cinfo);
//      cinfo.output_scanline = 0;
//#else
//      ERREXIT(cinfo, JERR_NOT_COMPILED);
//#endif /* QUANT_2PASS_SUPPORTED */
    }
    /* Ready for application to drive output pass through
     * jpeg_read_scanlines or jpeg_read_raw_data.
     */
    cinfo.global_state = cinfo.raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
    return true;
}

static bool get_dht (jpeg_decompress_struct cinfo)
/* Process a DHT marker */
{
    int length;
    byte[] bits = new byte[17];
    byte[] huffval = new byte[256];
    int i, index, count;
    JHUFF_TBL htblptr;

    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length = (cinfo.buffer[cinfo.bytes_offset++] & 0xFF) << 8;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length |= cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
    length -= 2;

    while (length > 16) {
        if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
        index = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;

//      TRACEMS1(cinfo, 1, JTRC_DHT, index);

        bits[0] = 0;
        count = 0;
        for (i = 1; i <= 16; i++) {
            if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
        bits[i] = cinfo.buffer[cinfo.bytes_offset++];
            count += bits[i] & 0xFF;
        }

        length -= 1 + 16;

//      TRACEMS8(cinfo, 2, JTRC_HUFFBITS,
//           bits[1], bits[2], bits[3], bits[4],
//           bits[5], bits[6], bits[7], bits[8]);
//      TRACEMS8(cinfo, 2, JTRC_HUFFBITS,
//           bits[9], bits[10], bits[11], bits[12],
//           bits[13], bits[14], bits[15], bits[16]);

        /* Here we just do minimal validation of the counts to avoid walking
         * off the end of our table space.  jdhuff.c will check more carefully.
         */
        if (count > 256 || (count) > length)
            error();
//          ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);

        for (i = 0; i < count; i++) {
            if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
            huffval[i] = cinfo.buffer[cinfo.bytes_offset++];
        }

        length -= count;

        if ((index & 0x10) !is 0) {      /* AC table definition */
            index -= 0x10;
            htblptr = cinfo.ac_huff_tbl_ptrs[index] = new JHUFF_TBL();
        } else {            /* DC table definition */
            htblptr = cinfo.dc_huff_tbl_ptrs[index] = new JHUFF_TBL();
        }

        if (index < 0 || index >= NUM_HUFF_TBLS)
            error();
//          ERREXIT1(cinfo, JERR_DHT_INDEX, index);

        System.arraycopy(bits, 0, htblptr.bits, 0, bits.length);
        System.arraycopy(huffval, 0, htblptr.huffval, 0, huffval.length);
    }

    if (length !is 0)
        error();
//      ERREXIT(cinfo, JERR_BAD_LENGTH);

    return true;
}


static bool get_dqt (jpeg_decompress_struct cinfo)
/* Process a DQT marker */
{
    int length;
    int n, i, prec;
    int tmp;
    JQUANT_TBL quant_ptr;

    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length = (cinfo.buffer[cinfo.bytes_offset++] & 0xFF) << 8;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length |= cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
    length -= 2;

    while (length > 0) {
        if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    n = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
        prec = n >> 4;
        n &= 0x0F;

//      TRACEMS2(cinfo, 1, JTRC_DQT, n, prec);

        if (n >= NUM_QUANT_TBLS)
            error();
//          ERREXIT1(cinfo, JERR_DQT_INDEX, n);

        if (cinfo.quant_tbl_ptrs[n] is null)
            cinfo.quant_tbl_ptrs[n] = new JQUANT_TBL();
        quant_ptr = cinfo.quant_tbl_ptrs[n];

        for (i = 0; i < DCTSIZE2; i++) {
            if (prec !is 0) {
                if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
                tmp = (cinfo.buffer[cinfo.bytes_offset++] & 0xFF) << 8;
                if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
                tmp |= cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
            } else {
                    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
                tmp = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
            }
            /* We convert the zigzag-order table to natural array order. */
            quant_ptr.quantval[jpeg_natural_order[i]] = cast(short) tmp;
        }

//      if (cinfo.err.trace_level >= 2) {
//          for (i = 0; i < DCTSIZE2; i += 8) {
//              TRACEMS8(cinfo, 2, JTRC_QUANTVALS,
//                  quant_ptr.quantval[i],   quant_ptr.quantval[i+1],
//                   quant_ptr.quantval[i+2], quant_ptr.quantval[i+3],
//                   quant_ptr.quantval[i+4], quant_ptr.quantval[i+5],
//                   quant_ptr.quantval[i+6], quant_ptr.quantval[i+7]);
//          }
//      }

        length -= (DCTSIZE2+1);
        if (prec !is 0) length -= DCTSIZE2;
    }

    if (length !is 0)
        error();
//      ERREXIT(cinfo, JERR_BAD_LENGTH);

    return true;
}

static bool get_dri (jpeg_decompress_struct cinfo)
/* Process a DRI marker */
{
    int length;
    int tmp;

    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length = (cinfo.buffer[cinfo.bytes_offset++] & 0xFF) << 8;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length |= cinfo.buffer[cinfo.bytes_offset++] & 0xFF;

    if (length !is 4)
    error();
//      ERREXIT(cinfo, JERR_BAD_LENGTH);

    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    tmp = (cinfo.buffer[cinfo.bytes_offset++] & 0xFF) << 8;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    tmp |= cinfo.buffer[cinfo.bytes_offset++] & 0xFF;

//  TRACEMS1(cinfo, 1, JTRC_DRI, tmp);

    cinfo.restart_interval = tmp;

    return true;
}

static bool get_dac (jpeg_decompress_struct cinfo)
/* Process a DAC marker */
{
    int length;
    int index, val;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length = (cinfo.buffer[cinfo.bytes_offset++] & 0xFF) << 8;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length |= cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
    length -= 2;

    while (length > 0) {
        if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
        index = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
        if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
        val = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;

        length -= 2;

//      TRACEMS2(cinfo, 1, JTRC_DAC, index, val);

        if (index < 0 || index >= (2*NUM_ARITH_TBLS))
            error();
//          ERREXIT1(cinfo, JERR_DAC_INDEX, index);

        if (index >= NUM_ARITH_TBLS) { /* define AC table */
            cinfo.arith_ac_K[index-NUM_ARITH_TBLS] = cast(byte) val;
        } else {            /* define DC table */
            cinfo.arith_dc_L[index] = cast(byte) (val & 0x0F);
            cinfo.arith_dc_U[index] = cast(byte) (val >> 4);
            if (cinfo.arith_dc_L[index] > cinfo.arith_dc_U[index])
                error();
//  ERREXIT1(cinfo, JERR_DAC_VALUE, val);
        }
    }

    if (length !is 0)
        error();
//      ERREXIT(cinfo, JERR_BAD_LENGTH);

    return true;
}


static bool get_sos (jpeg_decompress_struct cinfo)
/* Process a SOS marker */
{
    int length;
    int i, ci, n, c, cc;
    jpeg_component_info compptr = null;

    if (! cinfo.marker.saw_SOF)
        error();
//      ERREXIT(cinfo, JERR_SOS_NO_SOF);

    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length = (cinfo.buffer[cinfo.bytes_offset++] & 0xFF) << 8;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length |= cinfo.buffer[cinfo.bytes_offset++] & 0xFF;

    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    n = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;

//  TRACEMS1(cinfo, 1, JTRC_SOS, n);

    if (length !is (n * 2 + 6) || n < 1 || n > MAX_COMPS_IN_SCAN)
        error();
//      ERREXIT(cinfo, JERR_BAD_LENGTH);

    cinfo.comps_in_scan = n;

    /* Collect the component-spec parameters */

    for (i = 0; i < n; i++) {
        if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
        cc = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
        if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
        c = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;

        for (ci = 0; ci < cinfo.num_components; ci++) {
            compptr = cinfo.comp_info[ci];
            if (cc is compptr.component_id)
                break;
        }

        if (ci is cinfo.num_components)
            error();
//          ERREXIT1(cinfo, JERR_BAD_COMPONENT_ID, cc);

        cinfo.cur_comp_info[i] = compptr;
        compptr.dc_tbl_no = (c >> 4) & 15;
        compptr.ac_tbl_no = (c       ) & 15;

//      TRACEMS3(cinfo, 1, JTRC_SOS_COMPONENT, cc, compptr.dc_tbl_no, compptr.ac_tbl_no);
    }

    /* Collect the additional scan parameters Ss, Se, Ah/Al. */
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    c = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
    cinfo.Ss = c;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    c = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
    cinfo.Se = c;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    c = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
    cinfo.Ah = (c >> 4) & 15;
    cinfo.Al = (c        ) & 15;

//  TRACEMS4(cinfo, 1, JTRC_SOS_PARAMS, cinfo.Ss, cinfo.Se, cinfo.Ah, cinfo.Al);

    /* Prepare to scan data & restart markers */
    cinfo.marker.next_restart_num = 0;

    /* Count another SOS marker */
    cinfo.input_scan_number++;

    return true;
}

static bool get_sof (jpeg_decompress_struct cinfo, bool is_prog, bool is_arith) {
    int length;
    int c, ci;

    cinfo.progressive_mode = is_prog;
    cinfo.arith_code = is_arith;

    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length = (cinfo.buffer[cinfo.bytes_offset++] & 0xFF) << 8;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length |= cinfo.buffer[cinfo.bytes_offset++] & 0xFF;

    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    cinfo.data_precision = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;

    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    cinfo.image_height = (cinfo.buffer[cinfo.bytes_offset++] & 0xFF) << 8;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    cinfo.image_height |= cinfo.buffer[cinfo.bytes_offset++] & 0xFF;

    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    cinfo.image_width = (cinfo.buffer[cinfo.bytes_offset++] & 0xFF) << 8;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    cinfo.image_width |= cinfo.buffer[cinfo.bytes_offset++] & 0xFF;

    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    cinfo.num_components = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;

    length -= 8;

//  TRACEMS4(cinfo, 1, JTRC_SOF, cinfo.unread_marker,
//       cast(int) cinfo.image_width, cast(int) cinfo.image_height,
//       cinfo.num_components);

    if (cinfo.marker.saw_SOF)
        error();
//      ERREXIT(cinfo, JERR_SOF_DUPLICATE);

    /* We don't support files in which the image height is initially specified */
    /* as 0 and is later redefined by DNL.  As long as we have to check that,   */
    /* might as well have a general sanity check. */
    if (cinfo.image_height <= 0 || cinfo.image_width <= 0 || cinfo.num_components <= 0)
        error();
//      ERREXIT(cinfo, JERR_EMPTY_IMAGE);

    if (length !is (cinfo.num_components * 3))
        error();
//      ERREXIT(cinfo, JERR_BAD_LENGTH);

    if (cinfo.comp_info is null)    /* do only once, even if suspend */
        cinfo.comp_info = new jpeg_component_info[cinfo.num_components];

    for (ci = 0; ci < cinfo.num_components; ci++) {
        jpeg_component_info compptr = cinfo.comp_info[ci] = new jpeg_component_info();
        compptr.component_index = ci;
        if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
        compptr.component_id = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
        if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
        c = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
        compptr.h_samp_factor = (c >> 4) & 15;
        compptr.v_samp_factor = (c       ) & 15;
        if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
        compptr.quant_tbl_no = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;

//      TRACEMS4(cinfo, 1, JTRC_SOF_COMPONENT,
//           compptr.component_id, compptr.h_samp_factor,
//           compptr.v_samp_factor, compptr.quant_tbl_no);
    }

    cinfo.marker.saw_SOF = true;

    return true;
}

static void sep_upsample (jpeg_decompress_struct cinfo, byte[][][] input_buf, int[] input_buf_offset,
        int[] in_row_group_ctr, int in_row_groups_avail,
        byte[][] output_buf, int[] out_row_ctr, int out_rows_avail)
{
    jpeg_upsampler upsample = cinfo.upsample;
    int ci;
    jpeg_component_info compptr;
    int num_rows;

    /* Fill the conversion buffer, if it's empty */
    if (upsample.next_row_out >= cinfo.max_v_samp_factor) {
        for (ci = 0; ci < cinfo.num_components; ci++) {
            compptr = cinfo.comp_info[ci];
            /* Invoke per-component upsample method.    Notice we pass a POINTER
             * to color_buf[ci], so that fullsize_upsample can change it.
             */
            int offset = input_buf_offset[ci] + (in_row_group_ctr[0] * upsample.rowgroup_height[ci]);
            switch (upsample.methods[ci]) {
                case NOOP_UPSAMPLE: noop_upsample(cinfo, compptr, input_buf[ci], offset, upsample.color_buf, upsample.color_buf_offset, ci); break;
                case FULLSIZE_UPSAMPLE: fullsize_upsample(cinfo, compptr, input_buf[ci], offset, upsample.color_buf, upsample.color_buf_offset, ci); break;
                case H2V1_FANCY_UPSAMPLE: h2v1_fancy_upsample(cinfo, compptr, input_buf[ci], offset, upsample.color_buf, upsample.color_buf_offset, ci); break;
                case H2V1_UPSAMPLE: h2v1_upsample(cinfo, compptr, input_buf[ci], offset, upsample.color_buf, upsample.color_buf_offset, ci); break;
                case H2V2_FANCY_UPSAMPLE: h2v2_fancy_upsample(cinfo, compptr, input_buf[ci], offset, upsample.color_buf, upsample.color_buf_offset, ci); break;
                case H2V2_UPSAMPLE: h2v2_upsample(cinfo, compptr, input_buf[ci], offset, upsample.color_buf, upsample.color_buf_offset, ci); break;
                case INT_UPSAMPLE: int_upsample(cinfo, compptr, input_buf[ci], offset, upsample.color_buf, upsample.color_buf_offset, ci); break;
            default:
            }
        }
        upsample.next_row_out = 0;
    }

    /* Color-convert and emit rows */

    /* How many we have in the buffer: */
    num_rows =  (cinfo.max_v_samp_factor - upsample.next_row_out);
    /* Not more than the distance to the end of the image.  Need this test
     * in case the image height is not a multiple of max_v_samp_factor:
     */
    if (num_rows > upsample.rows_to_go)
        num_rows = upsample.rows_to_go;
    /* And not more than what the client can accept: */
    out_rows_avail -= out_row_ctr[0];
    if (num_rows > out_rows_avail)
        num_rows = out_rows_avail;

    switch (cinfo.cconvert.color_convert) {
        case NULL_CONVERT: null_convert (cinfo, upsample.color_buf, upsample.color_buf_offset, upsample.next_row_out, output_buf, out_row_ctr[0], num_rows); break;
        case GRAYSCALE_CONVERT: grayscale_convert (cinfo, upsample.color_buf, upsample.color_buf_offset, upsample.next_row_out, output_buf, out_row_ctr[0], num_rows); break;
        case YCC_RGB_CONVERT: ycc_rgb_convert (cinfo, upsample.color_buf, upsample.color_buf_offset, upsample.next_row_out, output_buf, out_row_ctr[0], num_rows); break;
        case GRAY_RGB_CONVERT: gray_rgb_convert (cinfo, upsample.color_buf, upsample.color_buf_offset, upsample.next_row_out, output_buf, out_row_ctr[0], num_rows); break;
        case YCCK_CMYK_CONVERT: error(); break;
            default:
    }

    /* Adjust counts */
    out_row_ctr[0] += num_rows;
    upsample.rows_to_go -= num_rows;
    upsample.next_row_out += num_rows;
    /* When the buffer is emptied, declare this input row group consumed */
    if (upsample.next_row_out >= cinfo.max_v_samp_factor) {
        in_row_group_ctr[0]++;
    }
}

static void noop_upsample (jpeg_decompress_struct cinfo, jpeg_component_info compptr,
     byte[][] input_data, int input_data_offset, byte[][][] output_data_ptr, int[] output_data_offset, int output_data_index)
{
    output_data_ptr[output_data_index] = null;  /* safety check */
}

static void fullsize_upsample (jpeg_decompress_struct cinfo, jpeg_component_info compptr,
     byte[][] input_data, int input_data_offset, byte[][][] output_data_ptr, int[] output_data_offset, int output_data_index)
{
    output_data_ptr[output_data_index] = input_data;
    output_data_offset[output_data_index] = input_data_offset;
}

static void h2v1_upsample (jpeg_decompress_struct cinfo, jpeg_component_info compptr,
     byte[][] input_data, int input_data_offset, byte[][][] output_data_ptr, int[] output_data_offset, int output_data_index)
{
    byte[][] output_data = output_data_ptr[output_data_index];
    byte[] inptr, outptr;
    byte invalue;
    int outend;
    int inrow;
    output_data_offset[output_data_index] = 0;

    for (inrow = 0; inrow < cinfo.max_v_samp_factor; inrow++) {
        inptr = input_data[inrow+input_data_offset];
        outptr = output_data[inrow];
        int inptr_offset = 0, outptr_offset = 0;
        outend = outptr_offset + cinfo.output_width;
        while (outptr_offset < outend) {
            invalue = inptr[inptr_offset++];    /* don't need GETJSAMPLE() here */
            outptr[outptr_offset++] = invalue;
            outptr[outptr_offset++] = invalue;
        }
    }
}

static void h2v2_upsample (jpeg_decompress_struct cinfo, jpeg_component_info compptr,
    byte[][] input_data, int input_data_offset, byte[][][] output_data_ptr, int[] output_data_offset, int output_data_index)
{
    byte[][] output_data = output_data_ptr[output_data_index];
    byte[] inptr, outptr;
    byte invalue;
    int outend;
    int inrow, outrow;
    output_data_offset[output_data_index] = 0;

    inrow = outrow = 0;
    while (outrow < cinfo.max_v_samp_factor) {
        inptr = input_data[inrow+input_data_offset];
        outptr = output_data[outrow];
        int inptr_offset = 0, outptr_offset = 0;
        outend = outptr_offset + cinfo.output_width;
        while (outptr_offset < outend) {
            invalue = inptr[inptr_offset++];    /* don't need GETJSAMPLE() here */
            outptr[outptr_offset++] = invalue;
            outptr[outptr_offset++] = invalue;
        }
        jcopy_sample_rows(output_data, outrow, output_data, outrow+1, 1, cinfo.output_width);
        inrow++;
        outrow += 2;
    }
}

static void h2v1_fancy_upsample (jpeg_decompress_struct cinfo, jpeg_component_info compptr,
     byte[][] input_data, int input_data_offset, byte[][][] output_data_ptr, int[] output_data_offset, int output_data_index)
{
    byte[][] output_data = output_data_ptr[output_data_index];
    byte[] inptr, outptr;
    int invalue;
    int colctr;
    int inrow;
    output_data_offset[output_data_index] = 0;

    for (inrow = 0; inrow < cinfo.max_v_samp_factor; inrow++) {
        inptr = input_data[inrow+input_data_offset];
        outptr = output_data[inrow];
        int inptr_offset = 0, outptr_offset = 0;
        /* Special case for first column */
        invalue = inptr[inptr_offset++] & 0xFF;
        outptr[outptr_offset++] = cast(byte) invalue;
        outptr[outptr_offset++] = cast(byte) ((invalue * 3 + (inptr[inptr_offset] & 0xFF) + 2) >> 2);

        for (colctr = compptr.downsampled_width - 2; colctr > 0; colctr--) {
            /* General case: 3/4 * nearer pixel + 1/4 * further pixel */
            invalue = (inptr[inptr_offset++] & 0xFF) * 3;
            outptr[outptr_offset++] = cast(byte) ((invalue + (inptr[inptr_offset-2] & 0xFF) + 1) >> 2);
            outptr[outptr_offset++] = cast(byte) ((invalue + (inptr[inptr_offset] & 0xFF) + 2) >> 2);
        }

        /* Special case for last column */
        invalue = (inptr[inptr_offset] & 0xFF);
        outptr[outptr_offset++] = cast(byte) ((invalue * 3 + (inptr[inptr_offset-1] & 0xFF) + 1) >> 2);
        outptr[outptr_offset++] = cast(byte) invalue;
    }
}

static void h2v2_fancy_upsample (jpeg_decompress_struct cinfo, jpeg_component_info compptr,
    byte[][] input_data, int input_data_offset, byte[][][] output_data_ptr, int[] output_data_offset, int output_data_index)
{
    byte[][] output_data = output_data_ptr[output_data_index];
    byte[] inptr0, inptr1, outptr;
    int thiscolsum, lastcolsum, nextcolsum;
    int colctr;
    int inrow, outrow, v;
    output_data_offset[output_data_index] = 0;

    inrow = outrow = 0;
    while (outrow < cinfo.max_v_samp_factor) {
        for (v = 0; v < 2; v++) {
            /* inptr0 points to nearest input row, inptr1 points to next nearest */
            inptr0 = input_data[inrow+input_data_offset];
            if (v is 0)     /* next nearest is row above */
                inptr1 = input_data[inrow-1+input_data_offset];
            else            /* next nearest is row below */
                inptr1 = input_data[inrow+1+input_data_offset];
            outptr = output_data[outrow++];

            int inptr0_offset = 0, inptr1_offset = 0, outptr_offset = 0;

            /* Special case for first column */
            thiscolsum = (inptr0[inptr0_offset++] & 0xFF) * 3 + (inptr1[inptr1_offset++] & 0xFF);
            nextcolsum = (inptr0[inptr0_offset++] & 0xFF) * 3 + (inptr1[inptr1_offset++] & 0xFF);
            outptr[outptr_offset++] = cast(byte) ((thiscolsum * 4 + 8) >> 4);
            outptr[outptr_offset++] = cast(byte) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
            lastcolsum = thiscolsum; thiscolsum = nextcolsum;

            for (colctr = compptr.downsampled_width - 2; colctr > 0; colctr--) {
                /* General case: 3/4 * nearer pixel + 1/4 * further pixel in each */
                /* dimension, thus 9/16, 3/16, 3/16, 1/16 overall */
                nextcolsum = (inptr0[inptr0_offset++] & 0xFF) * 3 + (inptr1[inptr1_offset++] & 0xFF);
                outptr[outptr_offset++] = cast(byte) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
                outptr[outptr_offset++] = cast(byte) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
                lastcolsum = thiscolsum; thiscolsum = nextcolsum;
            }

            /* Special case for last column */
            outptr[outptr_offset++] = cast(byte) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
            outptr[outptr_offset++] = cast(byte) ((thiscolsum * 4 + 7) >> 4);
        }
        inrow++;
    }
}

static void int_upsample (jpeg_decompress_struct cinfo, jpeg_component_info compptr,
     byte[][] input_data, int input_data_offset, byte[][][] output_data_ptr, int[] output_data_offset, int output_data_index)
{
    jpeg_upsampler upsample = cinfo.upsample;
    byte[][] output_data = output_data_ptr[output_data_index];
    byte[] inptr, outptr;
    byte invalue;
    int h;
    int outend;
    int h_expand, v_expand;
    int inrow, outrow;
    output_data_offset[output_data_index] = 0;

    h_expand = upsample.h_expand[compptr.component_index];
    v_expand = upsample.v_expand[compptr.component_index];

    inrow = outrow = 0;
    while (outrow < cinfo.max_v_samp_factor) {
        /* Generate one output row with proper horizontal expansion */
        inptr = input_data[inrow+input_data_offset];
        int inptr_offset = 0;
        outptr = output_data[outrow];
        int outptr_offset = 0;
        outend = outptr_offset + cinfo.output_width;
        while (outptr_offset < outend) {
            invalue = inptr[inptr_offset++];    /* don't need GETJSAMPLE() here */
            for (h = h_expand; h > 0; h--) {
                outptr[outptr_offset++] = invalue;
            }
        }
        /* Generate any additional output rows by duplicating the first one */
        if (v_expand > 1) {
            jcopy_sample_rows(output_data, outrow, output_data, outrow+1, v_expand-1, cinfo.output_width);
        }
        inrow++;
        outrow += v_expand;
    }
}

static void null_convert (jpeg_decompress_struct cinfo,
    byte[][][] input_buf, int[] input_buf_offset, int input_row,
    byte[][] output_buf, int output_buf_offset, int num_rows)
{
    byte[] inptr, outptr;
    int count;
    int num_components = cinfo.num_components;
    int num_cols = cinfo.output_width;
    int ci;

    while (--num_rows >= 0) {
        for (ci = 0; ci < num_components; ci++) {
            inptr = input_buf[ci][input_row+input_buf_offset[0]];
            outptr = output_buf[output_buf_offset];
            /* BGR instead of RGB */
            int offset = 0;
            switch (ci) {
                case 2: offset = RGB_BLUE; break;
                case 1: offset = RGB_GREEN; break;
                case 0: offset = RGB_RED; break;
            default:
            }
            int outptr_offset = offset, inptr_offset = 0;
            for (count = num_cols; count > 0; count--) {
                outptr[outptr_offset] = inptr[inptr_offset++];  /* needn't bother with GETJSAMPLE() here */
                outptr_offset += num_components;
            }
        }
        input_row++;
        output_buf_offset++;
    }
}

static void grayscale_convert (jpeg_decompress_struct cinfo,
    byte[][][] input_buf, int[] input_buf_offset, int input_row,
    byte[][] output_buf, int output_buf_offset, int num_rows)
{
  jcopy_sample_rows(input_buf[0], input_row+input_buf_offset[0], output_buf, output_buf_offset,
            num_rows, cinfo.output_width);
}

static void gray_rgb_convert (jpeg_decompress_struct cinfo,
    byte[][][] input_buf, int[] input_buf_offset, int input_row,
    byte[][] output_buf, int output_buf_offset, int num_rows)
{
    byte[] inptr, outptr;
    int col;
    int num_cols = cinfo.output_width;

    while (--num_rows >= 0) {
        inptr = input_buf[0][input_row+++input_buf_offset[0]];
        outptr = output_buf[output_buf_offset++];
        int outptr_offset = 0;
        for (col = 0; col < num_cols; col++) {
            /* We can dispense with GETJSAMPLE() here */
            outptr[RGB_RED+outptr_offset] = outptr[RGB_GREEN+outptr_offset] = outptr[RGB_BLUE+outptr_offset] = inptr[col];
            outptr_offset += RGB_PIXELSIZE;
        }
    }
}

static void ycc_rgb_convert (jpeg_decompress_struct cinfo,
    byte[][][] input_buf, int[] input_buf_offset, int input_row,
    byte[][] output_buf, int output_buf_offset, int num_rows)
{
    jpeg_color_deconverter cconvert = cinfo.cconvert;
    int y, cb, cr;
    byte[] outptr;
    byte[] inptr0, inptr1, inptr2;
    int col;
    int num_cols = cinfo.output_width;
    /* copy these pointers into registers if possible */
    byte[] range_limit = cinfo.sample_range_limit;
    int range_limit_offset = cinfo.sample_range_limit_offset;
    int[] Crrtab = cconvert.Cr_r_tab;
    int[] Cbbtab = cconvert.Cb_b_tab;
    int[] Crgtab = cconvert.Cr_g_tab;
    int[] Cbgtab = cconvert.Cb_g_tab;
//      SHIFT_TEMPS

    while (--num_rows >= 0) {
        inptr0 = input_buf[0][input_row+input_buf_offset[0]];
        inptr1 = input_buf[1][input_row+input_buf_offset[1]];
        inptr2 = input_buf[2][input_row+input_buf_offset[2]];
        input_row++;
        outptr = output_buf[output_buf_offset++];
        int outptr_offset = 0;
        for (col = 0; col < num_cols; col++) {
            y = (inptr0[col] & 0xFF);
            cb = (inptr1[col] & 0xFF);
            cr = (inptr2[col] & 0xFF);
            /* Range-limiting is essential due to noise introduced by DCT losses. */
            outptr[outptr_offset + RGB_RED] =   range_limit[y + Crrtab[cr] + range_limit_offset];
            outptr[outptr_offset + RGB_GREEN] = range_limit[y + ((Cbgtab[cb] + Crgtab[cr]>>SCALEBITS)) + range_limit_offset];
            outptr[outptr_offset + RGB_BLUE] =  range_limit[y + Cbbtab[cb] + range_limit_offset];
            outptr_offset += RGB_PIXELSIZE;
        }
    }
}

static bool process_APPn(int n, jpeg_decompress_struct cinfo) {
    if (n is 0 || n is 14) {
        return get_interesting_appn(cinfo);
    }
    return skip_variable(cinfo);
}

static bool process_COM(jpeg_decompress_struct cinfo) {
    return skip_variable(cinfo);
}

static void skip_input_data (jpeg_decompress_struct cinfo, int num_bytes) {
    if (num_bytes > 0) {
        while (num_bytes > cinfo.bytes_in_buffer - cinfo.bytes_offset) {
            num_bytes -= cinfo.bytes_in_buffer - cinfo.bytes_offset;
            if (!fill_input_buffer(cinfo)) error();
            /* note we assume that fill_input_buffer will never return FALSE,
             * so suspension need not be handled.
             */
        }
        cinfo.bytes_offset += num_bytes;
    }
}

static bool skip_variable (jpeg_decompress_struct cinfo)
/* Skip over an unknown or uninteresting variable-length marker */
{
    int length;

    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length = (cinfo.buffer[cinfo.bytes_offset++] & 0xFF) << 8;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length |= cinfo.buffer[cinfo.bytes_offset++] & 0xFF;

    length -= 2;

//  TRACEMS2(cinfo, 1, JTRC_MISC_MARKER, cinfo.unread_marker, cast(int) length);

    if (length > 0) {
        skip_input_data (cinfo, length);
    }

    return true;
}

static bool get_interesting_appn (jpeg_decompress_struct cinfo)
/* Process an APP0 or APP14 marker without saving it */
{
    int length;
    byte[] b = new byte[APPN_DATA_LEN];
    int i, numtoread;

    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length = (cinfo.buffer[cinfo.bytes_offset++] & 0xFF) << 8;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    length |= cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
    length -= 2;

    /* get the interesting part of the marker data */
    if (length >= APPN_DATA_LEN)
        numtoread = APPN_DATA_LEN;
    else if (length > 0)
        numtoread = length;
    else
        numtoread = 0;
    for (i = 0; i < numtoread; i++) {
        if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
        b[i] = cinfo.buffer[cinfo.bytes_offset++];
    }
    length -= numtoread;

    /* process it */
    switch (cinfo.unread_marker) {
        case M_APP0:
            examine_app0(cinfo, b, numtoread, length);
            break;
        case M_APP14:
            examine_app14(cinfo, b, numtoread, length);
            break;
        default:
            /* can't get here unless jpeg_save_markers chooses wrong processor */
            error();
//          ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo.unread_marker);
            break;
    }

    /* skip any remaining data -- could be lots */
    if (length > 0)
        skip_input_data (cinfo, length);

    return true;
}

static void examine_app0 (jpeg_decompress_struct cinfo, byte[] data, int datalen, int remaining)
/* Examine first few bytes from an APP0.
 * Take appropriate action if it is a JFIF marker.
 * datalen is # of bytes at data[], remaining is length of rest of marker data.
 */
{
    int totallen = datalen + remaining;

    if (datalen >= APP0_DATA_LEN &&
            (data[0] & 0xFF) is 0x4A &&
            (data[1] & 0xFF) is 0x46 &&
            (data[2] & 0xFF) is 0x49 &&
            (data[3] & 0xFF) is 0x46 &&
            (data[4] & 0xFF) is 0)
    {
        /* Found JFIF APP0 marker: save info */
        cinfo.saw_JFIF_marker = true;
        cinfo.JFIF_major_version = (data[5]);
        cinfo.JFIF_minor_version = cast(byte)(data[6] & 0xFF);
        cinfo.density_unit = cast(byte)(data[7] & 0xFF);
        cinfo.X_density = cast(short)(((data[8] & 0xFF) << 8) + (data[9] & 0xFF));
        cinfo.Y_density = cast(short)(((data[10] & 0xFF) << 8) + (data[11] & 0xFF));
        /* Check version.
         * Major version must be 1, anything else signals an incompatible change.
         * (We used to treat this as an error, but now it's a nonfatal warning,
         * because some bozo at Hijaak couldn't read the spec.)
         * Minor version should be 0..2, but process anyway if newer.
         */
        if (cinfo.JFIF_major_version !is 1) {
//          WARNMS2(cinfo, JWRN_JFIF_MAJOR,
//              cinfo.JFIF_major_version, cinfo.JFIF_minor_version);
        }
        /* Generate trace messages */
//      TRACEMS5(cinfo, 1, JTRC_JFIF,
//           cinfo.JFIF_major_version, cinfo.JFIF_minor_version,
//           cinfo.X_density, cinfo.Y_density, cinfo.density_unit);
        /* Validate thumbnail dimensions and issue appropriate messages */
        if (((data[12] & 0xFF) | (data[13]) & 0xFF) !is 0) {
//          TRACEMS2(cinfo, 1, JTRC_JFIF_THUMBNAIL,
//               GETJOCTET(data[12]), GETJOCTET(data[13]));
        }
        totallen -= APP0_DATA_LEN;
        if (totallen !is ((data[12] & 0xFF) * (data[13] & 0xFF) * 3)) {
//          TRACEMS1(cinfo, 1, JTRC_JFIF_BADTHUMBNAILSIZE, cast(int) totallen);
        }
    } else if (datalen >= 6 &&
            (data[0] & 0xFF) is 0x4A &&
            (data[1] & 0xFF) is 0x46 &&
            (data[2] & 0xFF) is 0x58 &&
            (data[3] & 0xFF) is 0x58 &&
            (data[4] & 0xFF) is 0)
    {
        /* Found JFIF "JFXX" extension APP0 marker */
        /* The library doesn't actually do anything with these,
         * but we try to produce a helpful trace message.
         */
        switch ((data[5]) & 0xFF) {
            case 0x10:
//              TRACEMS1(cinfo, 1, JTRC_THUMB_JPEG, cast(int) totallen);
                break;
            case 0x11:
//              TRACEMS1(cinfo, 1, JTRC_THUMB_PALETTE, cast(int) totallen);
                break;
            case 0x13:
//              TRACEMS1(cinfo, 1, JTRC_THUMB_RGB, cast(int) totallen);
                break;
            default:
//              TRACEMS2(cinfo, 1, JTRC_JFIF_EXTENSION, GETJOCTET(data[5]), cast(int) totallen);
            break;
        }
    } else {
        /* Start of APP0 does not match "JFIF" or "JFXX", or too short */
//      TRACEMS1(cinfo, 1, JTRC_APP0, cast(int) totallen);
    }
}

static void examine_app14 (jpeg_decompress_struct cinfo, byte[] data, int datalen, int remaining)
/* Examine first few bytes from an APP14.
 * Take appropriate action if it is an Adobe marker.
 * datalen is # of bytes at data[], remaining is length of rest of marker data.
 */
{
    int /*version, flags0, flags1, */transform;

    if (datalen >= APP14_DATA_LEN &&
            (data[0] & 0xFF) is 0x41 &&
            (data[1] & 0xFF) is 0x64 &&
            (data[2] & 0xFF) is 0x6F &&
            (data[3] & 0xFF) is 0x62 &&
            (data[4] & 0xFF) is 0x65)
    {
        /* Found Adobe APP14 marker */
//      version = ((data[5] & 0xFF) << 8) + (data[6] & 0xFF);
//      flags0 = ((data[7] & 0xFF) << 8) + (data[8] & 0xFF);
//      flags1 = ((data[9] & 0xFF) << 8) + (data[10] & 0xFF);
        transform = (data[11] & 0xFF);
//      TRACEMS4(cinfo, 1, JTRC_ADOBE, version, flags0, flags1, transform);
        cinfo.saw_Adobe_marker = true;
        cinfo.Adobe_transform = cast(byte) transform;
    } else {
        /* Start of APP14 does not match "Adobe", or too short */
//      TRACEMS1(cinfo, 1, JTRC_APP14, cast(int) (datalen + remaining));
    }
}

static bool get_soi (jpeg_decompress_struct cinfo) /* Process an SOI marker */ {
    int i;

//  TRACEMS(cinfo, 1, JTRC_SOI);

    if (cinfo.marker.saw_SOI)
        error();
//      ERREXIT(cinfo, JERR_SOI_DUPLICATE);

    /* Reset all parameters that are defined to be reset by SOI */

    for (i = 0; i < NUM_ARITH_TBLS; i++) {
        cinfo.arith_dc_L[i] = 0;
        cinfo.arith_dc_U[i] = 1;
        cinfo.arith_ac_K[i] = 5;
    }
    cinfo.restart_interval = 0;

    /* Set initial assumptions for colorspace etc */

    cinfo.jpeg_color_space = JCS_UNKNOWN;
    cinfo.CCIR601_sampling = false; /* Assume non-CCIR sampling??? */

    cinfo.saw_JFIF_marker = false;
    cinfo.JFIF_major_version = 1; /* set default JFIF APP0 values */
    cinfo.JFIF_minor_version = 1;
    cinfo.density_unit = 0;
    cinfo.X_density = 1;
    cinfo.Y_density = 1;
    cinfo.saw_Adobe_marker = false;
    cinfo.Adobe_transform = 0;

    cinfo.marker.saw_SOI = true;

    return true;
}

static void jinit_input_controller (jpeg_decompress_struct cinfo)
{
    /* Initialize state: can't use reset_input_controller since we don't
     * want to try to reset other modules yet.
     */
    jpeg_input_controller inputctl = cinfo.inputctl = new jpeg_input_controller();
    inputctl.has_multiple_scans = false; /* "unknown" would be better */
    inputctl.eoi_reached = false;
    inputctl.inheaders = true;
}

static void reset_marker_reader (jpeg_decompress_struct cinfo) {
    jpeg_marker_reader marker = cinfo.marker;

    cinfo.comp_info = null;     /* until allocated by get_sof */
    cinfo.input_scan_number = 0;        /* no SOS seen yet */
    cinfo.unread_marker = 0;        /* no pending marker */
    marker.saw_SOI = false;     /* set internal state too */
    marker.saw_SOF = false;
    marker.discarded_bytes = 0;
//  marker.cur_marker = null;
}

static void reset_input_controller (jpeg_decompress_struct cinfo) {
    jpeg_input_controller inputctl = cinfo.inputctl;

    inputctl.has_multiple_scans = false; /* "unknown" would be better */
    inputctl.eoi_reached = false;
    inputctl.inheaders = true;
    /* Reset other modules */
    reset_marker_reader (cinfo);
    /* Reset progression state -- would be cleaner if entropy decoder did this */
    cinfo.coef_bits = null;
}

static void finish_output_pass (jpeg_decompress_struct cinfo) {
    jpeg_decomp_master master = cinfo.master;

    if (cinfo.quantize_colors) {
        error(SWT.ERROR_NOT_IMPLEMENTED);
//      (*cinfo.cquantize.finish_pass) (cinfo);
    }
    master.pass_number++;
}

static void jpeg_destroy (jpeg_decompress_struct cinfo) {
    /* We need only tell the memory manager to release everything. */
    /* NB: mem pointer is NULL if memory mgr failed to initialize. */
//  if (cinfo.mem !is NULL)
//      (*cinfo.mem.self_destruct) (cinfo);
//  cinfo.mem = NULL;       /* be safe if jpeg_destroy is called twice */
    cinfo.global_state = 0; /* mark it destroyed */
}

static void jpeg_destroy_decompress (jpeg_decompress_struct cinfo) {
    jpeg_destroy(cinfo); /* use common routine */
}

static bool jpeg_input_complete (jpeg_decompress_struct cinfo) {
    /* Check for valid jpeg object */
    if (cinfo.global_state < DSTATE_START || cinfo.global_state > DSTATE_STOPPING)
        error();
//      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo.global_state);
    return cinfo.inputctl.eoi_reached;
}

static bool jpeg_start_output (jpeg_decompress_struct cinfo, int scan_number) {
    if (cinfo.global_state !is DSTATE_BUFIMAGE && cinfo.global_state !is DSTATE_PRESCAN)
        error();
//      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo.global_state);
    /* Limit scan number to valid range */
    if (scan_number <= 0)
        scan_number = 1;
    if (cinfo.inputctl.eoi_reached && scan_number > cinfo.input_scan_number)
        scan_number = cinfo.input_scan_number;
    cinfo.output_scan_number = scan_number;
    /* Perform any dummy output passes, and set up for the real pass */
    return output_pass_setup(cinfo);
}

static bool jpeg_finish_output (jpeg_decompress_struct cinfo) {
    if ((cinfo.global_state is DSTATE_SCANNING || cinfo.global_state is DSTATE_RAW_OK) && cinfo.buffered_image) {
        /* Terminate this pass. */
        /* We do not require the whole pass to have been completed. */
        finish_output_pass (cinfo);
        cinfo.global_state = DSTATE_BUFPOST;
    } else if (cinfo.global_state !is DSTATE_BUFPOST) {
        /* BUFPOST = repeat call after a suspension, anything else is error */
        error();
//      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo.global_state);
    }
    /* Read markers looking for SOS or EOI */
    while (cinfo.input_scan_number <= cinfo.output_scan_number && !cinfo.inputctl.eoi_reached) {
        if (consume_input (cinfo) is JPEG_SUSPENDED)
            return false;       /* Suspend, come back later */
    }
    cinfo.global_state = DSTATE_BUFIMAGE;
    return true;
}

static bool jpeg_finish_decompress (jpeg_decompress_struct cinfo) {
    if ((cinfo.global_state is DSTATE_SCANNING || cinfo.global_state is DSTATE_RAW_OK) && ! cinfo.buffered_image) {
        /* Terminate final pass of non-buffered mode */
        if (cinfo.output_scanline < cinfo.output_height)
            error();
//          ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
        finish_output_pass (cinfo);
        cinfo.global_state = DSTATE_STOPPING;
    } else if (cinfo.global_state is DSTATE_BUFIMAGE) {
        /* Finishing after a buffered-image operation */
        cinfo.global_state = DSTATE_STOPPING;
    } else if (cinfo.global_state !is DSTATE_STOPPING) {
        /* STOPPING = repeat call after a suspension, anything else is error */
        error();
//      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo.global_state);
    }
    /* Read until EOI */
    while (! cinfo.inputctl.eoi_reached) {
        if (consume_input (cinfo) is JPEG_SUSPENDED)
            return false;       /* Suspend, come back later */
    }
    /* Do final cleanup */
//  (*cinfo.src.term_source) (cinfo);
    /* We can use jpeg_abort to release memory and reset global_state */
    jpeg_abort(cinfo);
    return true;
}


static int jpeg_read_header (jpeg_decompress_struct cinfo, bool require_image) {
    int retcode;

    if (cinfo.global_state !is DSTATE_START && cinfo.global_state !is DSTATE_INHEADER)
        error();
//      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo.global_state);

    retcode = jpeg_consume_input(cinfo);

    switch (retcode) {
        case JPEG_REACHED_SOS:
            retcode = JPEG_HEADER_OK;
            break;
        case JPEG_REACHED_EOI:
            if (require_image)      /* Complain if application wanted an image */
                error();
//              ERREXIT(cinfo, JERR_NO_IMAGE);
            /* Reset to start state; it would be safer to require the application to
             * call jpeg_abort, but we can't change it now for compatibility reasons.
             * A side effect is to free any temporary memory (there shouldn't be any).
             */
            jpeg_abort(cinfo); /* sets state = DSTATE_START */
            retcode = JPEG_HEADER_TABLES_ONLY;
            break;
        case JPEG_SUSPENDED:
            /* no work */
            break;
        default:
    }

    return retcode;
}

static int dummy_consume_data (jpeg_decompress_struct cinfo) {
    return JPEG_SUSPENDED;  /* Always indicate nothing was done */
}

static int consume_data (jpeg_decompress_struct cinfo) {
    jpeg_d_coef_controller coef = cinfo.coef;
    int MCU_col_num;    /* index of current MCU within row */
    int blkn, ci, xindex, yindex, yoffset;
    int start_col;
//  short[][][][] buffer = new short[MAX_COMPS_IN_SCAN][][][];
    short[][] buffer_ptr;
    jpeg_component_info compptr;

//  /* Align the virtual buffers for the components used in this scan. */
//  for (ci = 0; ci < cinfo.comps_in_scan; ci++) {
//      compptr = cinfo.cur_comp_info[ci];
//      buffer[ci] = coef.whole_image[compptr.component_index];
//      /* Note: entropy decoder expects buffer to be zeroed,
//       * but this is handled automatically by the memory manager
//       * because we requested a pre-zeroed array.
//       */
//  }

    /* Loop to process one whole iMCU row */
    for (yoffset = coef.MCU_vert_offset; yoffset < coef.MCU_rows_per_iMCU_row; yoffset++) {
        for (MCU_col_num = coef.MCU_ctr; MCU_col_num < cinfo.MCUs_per_row; MCU_col_num++) {
            /* Construct list of pointers to DCT blocks belonging to this MCU */
            blkn = 0; /* index of current DCT block within MCU */
            for (ci = 0; ci < cinfo.comps_in_scan; ci++) {
                compptr = cinfo.cur_comp_info[ci];
                start_col = MCU_col_num * compptr.MCU_width;
                for (yindex = 0; yindex < compptr.MCU_height; yindex++) {
//                  buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
                    buffer_ptr = coef.whole_image[compptr.component_index][yindex+yoffset+cinfo.input_iMCU_row*compptr.v_samp_factor];
                    int buffer_ptr_offset = start_col;
                    for (xindex = 0; xindex < compptr.MCU_width; xindex++) {
                        coef.MCU_buffer[blkn++] = buffer_ptr[buffer_ptr_offset++];
                    }
                }
            }
            /* Try to fetch the MCU. */
            if (! cinfo.entropy.decode_mcu (cinfo, coef.MCU_buffer)) {
                /* Suspension forced; update state counters and exit */
                coef.MCU_vert_offset = yoffset;
                coef.MCU_ctr = MCU_col_num;
                return JPEG_SUSPENDED;
            }
        }
        /* Completed an MCU row, but perhaps not an iMCU row */
        coef.MCU_ctr = 0;
    }
    /* Completed the iMCU row, advance counters for next one */
    if (++(cinfo.input_iMCU_row) < cinfo.total_iMCU_rows) {
        coef.start_iMCU_row(cinfo);
        return JPEG_ROW_COMPLETED;
    }
    /* Completed the scan */
    finish_input_pass (cinfo);
    return JPEG_SCAN_COMPLETED;
}

static int consume_input (jpeg_decompress_struct cinfo) {
    switch (cinfo.inputctl.consume_input) {
        case COEF_CONSUME_INPUT:
             switch (cinfo.coef.consume_data) {
                case CONSUME_DATA: return consume_data(cinfo);
                case DUMMY_CONSUME_DATA: return dummy_consume_data(cinfo);
                default: error();
             }
             break;
        case INPUT_CONSUME_INPUT:
            return consume_markers(cinfo);
        default:
            error();
    }
    return 0;
}

static bool fill_input_buffer(jpeg_decompress_struct cinfo) {
    try {
        InputStream inputStream = cinfo.inputStream;
        int nbytes = inputStream.read(cinfo.buffer);
        if (nbytes <= 0) {
            if (cinfo.start_of_file)    /* Treat empty input file as fatal error */
                error();
//              ERREXIT(cinfo, JERR_INPUT_EMPTY);
//          WARNMS(cinfo, JWRN_JPEG_EOF);
            /* Insert a fake EOI marker */
            cinfo.buffer[0] = cast(byte)0xFF;
            cinfo.buffer[1] = cast(byte)M_EOI;
            nbytes = 2;
        }
        cinfo.bytes_in_buffer = nbytes;
        cinfo.bytes_offset = 0;
        cinfo.start_of_file = false;
    } catch (IOException e) {
        error(SWT.ERROR_IO);
        return false;
    }
    return true;
}

static bool first_marker (jpeg_decompress_struct cinfo) {
    /* Like next_marker, but used to obtain the initial SOI marker. */
    /* For this marker, we do not allow preceding garbage or fill; otherwise,
     * we might well scan an entire input file before realizing it ain't JPEG.
     * If an application wants to process non-JFIF files, it must seek to the
     * SOI before calling the JPEG library.
     */
    int c, c2;

    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    c = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
    if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
    c2 = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
    if (c !is 0xFF || c2 !is M_SOI)
        error();
//      ERREXIT2(cinfo, JERR_NO_SOI, c, c2);

    cinfo.unread_marker = c2;

    return true;
}

static bool next_marker (jpeg_decompress_struct cinfo) {
    int c;

    for (;;) {
        if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
        c = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
        /* Skip any non-FF bytes.
         * This may look a bit inefficient, but it will not occur in a valid file.
         * We sync after each discarded byte so that a suspending data source
         * can discard the byte from its buffer.
         */
        while (c !is 0xFF) {
            cinfo.marker.discarded_bytes++;
            if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
            c = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
        }
        /* This loop swallows any duplicate FF bytes.   Extra FFs are legal as
         * pad bytes, so don't count them in discarded_bytes.   We assume there
         * will not be so many consecutive FF bytes as to overflow a suspending
         * data source's input buffer.
         */
        do {
             if (cinfo.bytes_offset is cinfo.bytes_in_buffer) fill_input_buffer(cinfo);
                c = cinfo.buffer[cinfo.bytes_offset++] & 0xFF;
        } while (c is 0xFF);
        if (c !is 0)
            break;          /* found a valid marker, exit loop */
        /* Reach here if we found a stuffed-zero data sequence (FF/00).
         * Discard it and loop back to try again.
         */
        cinfo.marker.discarded_bytes += 2;
    }

    if (cinfo.marker.discarded_bytes !is 0) {
//      WARNMS2(cinfo, JWRN_EXTRANEOUS_DATA, cinfo.marker.discarded_bytes, c);
        cinfo.marker.discarded_bytes = 0;
    }

    cinfo.unread_marker = c;

    return true;
}

static int read_markers (jpeg_decompress_struct cinfo) {
    /* Outer loop repeats once for each marker. */
    for (;;) {
        /* Collect the marker proper, unless we already did. */
        /* NB: first_marker() enforces the requirement that SOI appear first. */
        if (cinfo.unread_marker is 0) {
            if (! cinfo.marker.saw_SOI) {
                if (! first_marker(cinfo))
                    return JPEG_SUSPENDED;
                } else {
                    if (! next_marker(cinfo))
                        return JPEG_SUSPENDED;
                }
        }
        /* At this point cinfo.unread_marker contains the marker code and the
         * input point is just past the marker proper, but before any parameters.
         * A suspension will cause us to return with this state still true.
         */
        switch (cinfo.unread_marker) {
            case M_SOI:
                if (! get_soi(cinfo))
                    return JPEG_SUSPENDED;
                break;

            case M_SOF0:        /* Baseline */
            case M_SOF1:        /* Extended sequential, Huffman */
                if (! get_sof(cinfo, false, false))
                    return JPEG_SUSPENDED;
                break;

            case M_SOF2:        /* Progressive, Huffman */
                if (! get_sof(cinfo, true, false))
                    return JPEG_SUSPENDED;
                break;

            case M_SOF9:        /* Extended sequential, arithmetic */
                if (! get_sof(cinfo, false, true))
                    return JPEG_SUSPENDED;
                break;

            case M_SOF10:       /* Progressive, arithmetic */
                if (! get_sof(cinfo, true, true))
                    return JPEG_SUSPENDED;
                break;

            /* Currently unsupported SOFn types */
            case M_SOF3:        /* Lossless, Huffman */
            case M_SOF5:        /* Differential sequential, Huffman */
            case M_SOF6:        /* Differential progressive, Huffman */
            case M_SOF7:        /* Differential lossless, Huffman */
            case M_JPG:         /* Reserved for JPEG extensions */
            case M_SOF11:       /* Lossless, arithmetic */
            case M_SOF13:       /* Differential sequential, arithmetic */
            case M_SOF14:       /* Differential progressive, arithmetic */
            case M_SOF15:       /* Differential lossless, arithmetic */
                error();
//              ERREXIT1(cinfo, JERR_SOF_UNSUPPORTED, cinfo.unread_marker);
                break;

            case M_SOS:
                if (! get_sos(cinfo))
                    return JPEG_SUSPENDED;
                cinfo.unread_marker = 0;    /* processed the marker */
                return JPEG_REACHED_SOS;

            case M_EOI:
//              TRACEMS(cinfo, 1, JTRC_EOI);
                cinfo.unread_marker = 0;    /* processed the marker */
                return JPEG_REACHED_EOI;

            case M_DAC:
                if (! get_dac(cinfo))
                    return JPEG_SUSPENDED;
                break;

            case M_DHT:
                if (! get_dht(cinfo))
                    return JPEG_SUSPENDED;
                break;

            case M_DQT:
                if (! get_dqt(cinfo))
                    return JPEG_SUSPENDED;
                break;

            case M_DRI:
                if (! get_dri(cinfo))
                    return JPEG_SUSPENDED;
                break;

            case M_APP0:
            case M_APP1:
            case M_APP2:
            case M_APP3:
            case M_APP4:
            case M_APP5:
            case M_APP6:
            case M_APP7:
            case M_APP8:
            case M_APP9:
            case M_APP10:
            case M_APP11:
            case M_APP12:
            case M_APP13:
            case M_APP14:
            case M_APP15:
                if (! process_APPn(cinfo.unread_marker - M_APP0, cinfo))
                    return JPEG_SUSPENDED;
                break;

            case M_COM:
                if (! process_COM(cinfo))
                    return JPEG_SUSPENDED;
                break;

            case M_RST0:        /* these are all parameterless */
            case M_RST1:
            case M_RST2:
            case M_RST3:
            case M_RST4:
            case M_RST5:
            case M_RST6:
            case M_RST7:
            case M_TEM:
//              TRACEMS1(cinfo, 1, JTRC_PARMLESS_MARKER, cinfo.unread_marker);
                break;

            case M_DNL:         /* Ignore DNL ... perhaps the wrong thing */
                if (! skip_variable(cinfo))
                    return JPEG_SUSPENDED;
                break;

            default:            /* must be DHP, EXP, JPGn, or RESn */
                /* For now, we treat the reserved markers as fatal errors since they are
                 * likely to be used to signal incompatible JPEG Part 3 extensions.
                 * Once the JPEG 3 version-number marker is well defined, this code
                 * ought to change!
                 */
                error();
 //             ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo.unread_marker);
                break;
        }
        /* Successfully processed marker, so reset state variable */
        cinfo.unread_marker = 0;
    } /* end loop */
}

static long jdiv_round_up (long a, long b)
/* Compute a/b rounded up to next integer, ie, ceil(a/b) */
/* Assumes a >= 0, b > 0 */
{
    return (a + b - 1) / b;
}

static void initial_setup (jpeg_decompress_struct cinfo)
/* Called once, when first SOS marker is reached */
{
    int ci;
    jpeg_component_info compptr;

    /* Make sure image isn't bigger than I can handle */
    if (cinfo.image_height >    JPEG_MAX_DIMENSION || cinfo.image_width > JPEG_MAX_DIMENSION)
        error();
//      ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);

    /* For now, precision must match compiled-in value... */
    if (cinfo.data_precision !is BITS_IN_JSAMPLE)
        error(" [data precision=" ~ to!(String)(cinfo.data_precision) ~ "]");
//      ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo.data_precision);

    /* Check that number of components won't exceed internal array sizes */
    if (cinfo.num_components > MAX_COMPONENTS)
        error();
//      ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo.num_components, MAX_COMPONENTS);

    /* Compute maximum sampling factors; check factor validity */
    cinfo.max_h_samp_factor = 1;
    cinfo.max_v_samp_factor = 1;
    for (ci = 0; ci < cinfo.num_components; ci++) {
        compptr = cinfo.comp_info[ci];
        if (compptr.h_samp_factor<=0 || compptr.h_samp_factor>MAX_SAMP_FACTOR || compptr.v_samp_factor<=0 || compptr.v_samp_factor>MAX_SAMP_FACTOR)
            error();
//          ERREXIT(cinfo, JERR_BAD_SAMPLING);
        cinfo.max_h_samp_factor = Math.max(cinfo.max_h_samp_factor, compptr.h_samp_factor);
        cinfo.max_v_samp_factor = Math.max(cinfo.max_v_samp_factor, compptr.v_samp_factor);
    }

    /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
     * In the full decompressor, this will be overridden by jdmaster.c;
     * but in the transcoder, jdmaster.c is not used, so we must do it here.
     */
    cinfo.min_DCT_scaled_size = DCTSIZE;

    /* Compute dimensions of components */
    for (ci = 0; ci < cinfo.num_components; ci++) {
        compptr = cinfo.comp_info[ci];
        compptr.DCT_scaled_size = DCTSIZE;
        /* Size in DCT blocks */
        compptr.width_in_blocks = cast(int)jdiv_round_up(cast(long) cinfo.image_width * cast(long) compptr.h_samp_factor, (cinfo.max_h_samp_factor * DCTSIZE));
        compptr.height_in_blocks = cast(int)jdiv_round_up(cast(long) cinfo.image_height * cast(long) compptr.v_samp_factor, (cinfo.max_v_samp_factor * DCTSIZE));
        /* downsampled_width and downsampled_height will also be overridden by
         * jdmaster.c if we are doing full decompression.   The transcoder library
         * doesn't use these values, but the calling application might.
         */
        /* Size in samples */
        compptr.downsampled_width = cast(int)jdiv_round_up(cast(long) cinfo.image_width * cast(long) compptr.h_samp_factor, cinfo.max_h_samp_factor);
        compptr.downsampled_height = cast(int)jdiv_round_up(cast(long) cinfo.image_height * cast(long) compptr.v_samp_factor, cinfo.max_v_samp_factor);
        /* Mark component needed, until color conversion says otherwise */
        compptr.component_needed = true;
        /* Mark no quantization table yet saved for component */
        compptr.quant_table = null;
    }

    /* Compute number of fully interleaved MCU rows. */
    cinfo.total_iMCU_rows = cast(int)jdiv_round_up( cinfo.image_height, (cinfo.max_v_samp_factor*DCTSIZE));

    /* Decide whether file contains multiple scans */
    if (cinfo.comps_in_scan < cinfo.num_components || cinfo.progressive_mode)
        cinfo.inputctl.has_multiple_scans = true;
    else
        cinfo.inputctl.has_multiple_scans = false;
}


static void per_scan_setup (jpeg_decompress_struct cinfo)
/* Do computations that are needed before processing a JPEG scan */
/* cinfo.comps_in_scan and cinfo.cur_comp_info[] were set from SOS marker */
{
    int ci, mcublks, tmp = 0;
    jpeg_component_info compptr;

    if (cinfo.comps_in_scan is 1) {

        /* Noninterleaved (single-component) scan */
        compptr = cinfo.cur_comp_info[0];

        /* Overall image size in MCUs */
        cinfo.MCUs_per_row = compptr.width_in_blocks;
        cinfo.MCU_rows_in_scan = compptr.height_in_blocks;

        /* For noninterleaved scan, always one block per MCU */
        compptr.MCU_width = 1;
        compptr.MCU_height = 1;
        compptr.MCU_blocks = 1;
        compptr.MCU_sample_width = compptr.DCT_scaled_size;
        compptr.last_col_width = 1;
        /* For noninterleaved scans, it is convenient to define last_row_height
         * as the number of block rows present in the last iMCU row.
         */
        tmp = (compptr.height_in_blocks % compptr.v_samp_factor);
        if (tmp is 0) tmp = compptr.v_samp_factor;
        compptr.last_row_height = tmp;

        /* Prepare array describing MCU composition */
        cinfo.blocks_in_MCU = 1;
        cinfo.MCU_membership[0] = 0;

    } else {

        /* Interleaved (multi-component) scan */
        if (cinfo.comps_in_scan <= 0 || cinfo.comps_in_scan > MAX_COMPS_IN_SCAN)
            error();
//          ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo.comps_in_scan, MAX_COMPS_IN_SCAN);

        /* Overall image size in MCUs */
        cinfo.MCUs_per_row = cast(int)jdiv_round_up( cinfo.image_width, (cinfo.max_h_samp_factor*DCTSIZE));
        cinfo.MCU_rows_in_scan = cast(int)jdiv_round_up( cinfo.image_height, (cinfo.max_v_samp_factor*DCTSIZE));

        cinfo.blocks_in_MCU = 0;

        for (ci = 0; ci < cinfo.comps_in_scan; ci++) {
            compptr = cinfo.cur_comp_info[ci];
            /* Sampling factors give # of blocks of component in each MCU */
            compptr.MCU_width = compptr.h_samp_factor;
            compptr.MCU_height = compptr.v_samp_factor;
            compptr.MCU_blocks = compptr.MCU_width * compptr.MCU_height;
            compptr.MCU_sample_width = compptr.MCU_width * compptr.DCT_scaled_size;
            /* Figure number of non-dummy blocks in last MCU column & row */
            tmp = (compptr.width_in_blocks % compptr.MCU_width);
            if (tmp is 0) tmp = compptr.MCU_width;
            compptr.last_col_width = tmp;
            tmp = (compptr.height_in_blocks % compptr.MCU_height);
            if (tmp is 0) tmp = compptr.MCU_height;
            compptr.last_row_height = tmp;
            /* Prepare array describing MCU composition */
            mcublks = compptr.MCU_blocks;
            if (cinfo.blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU)
                error();
//  ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
            while (mcublks-- > 0) {
                cinfo.MCU_membership[cinfo.blocks_in_MCU++] = ci;
            }
        }

    }
}

static void latch_quant_tables (jpeg_decompress_struct cinfo) {
    int ci, qtblno;
    jpeg_component_info compptr;
    JQUANT_TBL qtbl;

    for (ci = 0; ci < cinfo.comps_in_scan; ci++) {
        compptr = cinfo.cur_comp_info[ci];
        /* No work if we already saved Q-table for this component */
        if (compptr.quant_table !is null)
            continue;
        /* Make sure specified quantization table is present */
        qtblno = compptr.quant_tbl_no;
        if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS || cinfo.quant_tbl_ptrs[qtblno] is null)
            error();
//          ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
        /* OK, save away the quantization table */
        qtbl = new JQUANT_TBL();
        System.arraycopy(cinfo.quant_tbl_ptrs[qtblno].quantval, 0, qtbl.quantval, 0, qtbl.quantval.length);
        qtbl.sent_table = cinfo.quant_tbl_ptrs[qtblno].sent_table;
        compptr.quant_table = qtbl;
    }
}

static void jpeg_make_d_derived_tbl (jpeg_decompress_struct cinfo, bool isDC, int tblno, d_derived_tbl dtbl) {
    JHUFF_TBL htbl;
    int p, i = 0, l, si, numsymbols;
    int lookbits, ctr;
    byte[] huffsize = new byte[257];
    int[] huffcode = new int[257];
    int code;

    /* Note that huffsize[] and huffcode[] are filled in code-length order,
     * paralleling the order of the symbols themselves in htbl.huffval[].
     */

    /* Find the input Huffman table */
    if (tblno < 0 || tblno >= NUM_HUFF_TBLS)
        error();
//      ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);
    htbl = isDC ? cinfo.dc_huff_tbl_ptrs[tblno] : cinfo.ac_huff_tbl_ptrs[tblno];
    if (htbl is null)
        error();
//      ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);

    /* Allocate a workspace if we haven't already done so. */
    dtbl.pub = htbl;        /* fill in back link */

    /* Figure C.1: make table of Huffman code length for each symbol */

    p = 0;
    for (l = 1; l <= 16; l++) {
        i = htbl.bits[l] & 0xFF;
        if (i < 0 || p + i > 256)   /* protect against table overrun */
            error();
//          ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
        while (i-- !is 0)
            huffsize[p++] = cast(byte) l;
    }
    huffsize[p] = 0;
    numsymbols = p;

    /* Figure C.2: generate the codes themselves */
    /* We also validate that the counts represent a legal Huffman code tree. */

    code = 0;
    si = huffsize[0];
    p = 0;
    while ( huffsize[p] !is 0) {
        while (( huffsize[p]) is si) {
            huffcode[p++] = code;
            code++;
        }
        /* code is now 1 more than the last code used for codelength si; but
         * it must still fit in si bits, since no code is allowed to be all ones.
         */
        if (( code) >= (( 1) << si))
            error();
//          ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
        code <<= 1;
        si++;
    }

    /* Figure F.15: generate decoding tables for bit-sequential decoding */

    p = 0;
    for (l = 1; l <= 16; l++) {
        if ((htbl.bits[l] & 0xFF) !is 0) {
            /* valoffset[l] = huffval[] index of 1st symbol of code length l,
             * minus the minimum code of length l
             */
            dtbl.valoffset[l] = p - huffcode[p];
            p += (htbl.bits[l] & 0xFF);
            dtbl.maxcode[l] = huffcode[p-1]; /* maximum code of length l */
        } else {
            dtbl.maxcode[l] = -1;   /* -1 if no codes of this length */
        }
    }
    dtbl.maxcode[17] = 0xFFFFF; /* ensures jpeg_huff_decode terminates */

    /* Compute lookahead tables to speed up decoding.
     * First we set all the table entries to 0, indicating "too long";
     * then we iterate through the Huffman codes that are short enough and
     * fill in all the entries that correspond to bit sequences starting
     * with that code.
     */

    for (int j = 0; j < dtbl.look_nbits.length; j++) {
        dtbl.look_nbits[j] = 0;
    }

    p = 0;
    for (l = 1; l <= HUFF_LOOKAHEAD; l++) {
        for (i = 1; i <= (htbl.bits[l] & 0xFF); i++, p++) {
            /* l = current code's length, p = its index in huffcode[] & huffval[]. */
            /* Generate left-justified code followed by all possible bit sequences */
            lookbits = huffcode[p] << (HUFF_LOOKAHEAD-l);
            for (ctr = 1 << (HUFF_LOOKAHEAD-l); ctr > 0; ctr--) {
                dtbl.look_nbits[lookbits] = l;
                dtbl.look_sym[lookbits] = htbl.huffval[p];
                lookbits++;
            }
        }
    }

    /* Validate symbols as being reasonable.
     * For AC tables, we make no check, but accept all byte values 0..255.
     * For DC tables, we require the symbols to be in range 0..15.
     * (Tighter bounds could be applied depending on the data depth and mode,
     * but this is sufficient to ensure safe decoding.)
     */
    if (isDC) {
        for (i = 0; i < numsymbols; i++) {
            int sym = htbl.huffval[i] & 0xFF;
            if (sym < 0 || sym > 15)
                error();
//              ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
        }
    }
}

static void start_input_pass (jpeg_decompress_struct cinfo) {
    per_scan_setup(cinfo);
    latch_quant_tables(cinfo);
    cinfo.entropy.start_pass(cinfo);
    cinfo.coef.start_input_pass (cinfo);
    cinfo.inputctl.consume_input = COEF_CONSUME_INPUT;
}

static void finish_input_pass (jpeg_decompress_struct cinfo) {
    cinfo.inputctl.consume_input = INPUT_CONSUME_INPUT;
}

static int consume_markers (jpeg_decompress_struct cinfo) {
    jpeg_input_controller inputctl = cinfo.inputctl;
    int val;

    if (inputctl.eoi_reached) /* After hitting EOI, read no further */
        return JPEG_REACHED_EOI;

    val = read_markers (cinfo);

    switch (val) {
    case JPEG_REACHED_SOS:  /* Found SOS */
        if (inputctl.inheaders) {   /* 1st SOS */
            initial_setup(cinfo);
            inputctl.inheaders = false;
            /* Note: start_input_pass must be called by jdmaster.c
             * before any more input can be consumed.   jdapimin.c is
             * responsible for enforcing this sequencing.
             */
        } else {            /* 2nd or later SOS marker */
            if (! inputctl.has_multiple_scans)
                error();
//              ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
            start_input_pass(cinfo);
        }
        break;
    case JPEG_REACHED_EOI:  /* Found EOI */
        inputctl.eoi_reached = true;
        if (inputctl.inheaders) {   /* Tables-only datastream, apparently */
            if (cinfo.marker.saw_SOF)
                error();
//              ERREXIT(cinfo, JERR_SOF_NO_SOS);
        } else {
            /* Prevent infinite loop in coef ctlr's decompress_data routine
             * if user set output_scan_number larger than number of scans.
             */
            if (cinfo.output_scan_number > cinfo.input_scan_number)
                cinfo.output_scan_number = cinfo.input_scan_number;
        }
        break;
    case JPEG_SUSPENDED:
        break;
    default:
    }

    return val;
}

static void default_decompress_parms (jpeg_decompress_struct cinfo) {
    /* Guess the input colorspace, and set output colorspace accordingly. */
    /* (Wish JPEG committee had provided a real way to specify this...) */
    /* Note application may override our guesses. */
    switch (cinfo.num_components) {
        case 1:
            cinfo.jpeg_color_space = JCS_GRAYSCALE;
            cinfo.out_color_space = JCS_GRAYSCALE;
            break;

        case 3:
            if (cinfo.saw_JFIF_marker) {
                cinfo.jpeg_color_space = JCS_YCbCr; /* JFIF implies YCbCr */
            } else if (cinfo.saw_Adobe_marker) {
                switch (cinfo.Adobe_transform) {
                    case 0:
                        cinfo.jpeg_color_space = JCS_RGB;
                        break;
                    case 1:
                        cinfo.jpeg_color_space = JCS_YCbCr;
                        break;
                    default:
//                      WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo.Adobe_transform);
                        cinfo.jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
                    break;
                }
            } else {
                /* Saw no special markers, try to guess from the component IDs */
                int cid0 = cinfo.comp_info[0].component_id;
                int cid1 = cinfo.comp_info[1].component_id;
                int cid2 = cinfo.comp_info[2].component_id;

                if (cid0 is 1 && cid1 is 2 && cid2 is 3)
                    cinfo.jpeg_color_space = JCS_YCbCr; /* assume JFIF w/out marker */
                else if (cid0 is 82 && cid1 is 71 && cid2 is 66)
                    cinfo.jpeg_color_space = JCS_RGB; /* ASCII 'R', 'G', 'B' */
                else {
//                  TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);
                    cinfo.jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
                }
            }
            /* Always guess RGB is proper output colorspace. */
            cinfo.out_color_space = JCS_RGB;
            break;

        case 4:
            if (cinfo.saw_Adobe_marker) {
                switch (cinfo.Adobe_transform) {
                    case 0:
                        cinfo.jpeg_color_space = JCS_CMYK;
                        break;
                    case 2:
                        cinfo.jpeg_color_space = JCS_YCCK;
                        break;
                    default:
//                      WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo.Adobe_transform);
                        cinfo.jpeg_color_space = JCS_YCCK; /* assume it's YCCK */
                        break;
                }
            } else {
                /* No special markers, assume straight CMYK. */
                cinfo.jpeg_color_space = JCS_CMYK;
            }
            cinfo.out_color_space = JCS_CMYK;
            break;

        default:
            cinfo.jpeg_color_space = JCS_UNKNOWN;
            cinfo.out_color_space = JCS_UNKNOWN;
            break;
    }

    /* Set defaults for other decompression parameters. */
    cinfo.scale_num = 1;        /* 1:1 scaling */
    cinfo.scale_denom = 1;
    cinfo.output_gamma = 1.0;
    cinfo.buffered_image = false;
    cinfo.raw_data_out = false;
    cinfo.dct_method = JDCT_DEFAULT;
    cinfo.do_fancy_upsampling = true;
    cinfo.do_block_smoothing = true;
    cinfo.quantize_colors = false;
    /* We set these in case application only sets quantize_colors. */
    cinfo.dither_mode = JDITHER_FS;
    cinfo.two_pass_quantize = true;
    cinfo.desired_number_of_colors = 256;
    cinfo.colormap = null;
    /* Initialize for no mode change in buffered-image mode. */
    cinfo.enable_1pass_quant = false;
    cinfo.enable_external_quant = false;
    cinfo.enable_2pass_quant = false;
}

static void init_source(jpeg_decompress_struct cinfo) {
    cinfo.buffer = new byte[INPUT_BUFFER_SIZE];
    cinfo.bytes_in_buffer = 0;
    cinfo.bytes_offset = 0;
    cinfo.start_of_file = true;
}

static int jpeg_consume_input (jpeg_decompress_struct cinfo) {
    int retcode = JPEG_SUSPENDED;

    /* NB: every possible DSTATE value should be listed in this switch */
    switch (cinfo.global_state) {
    case DSTATE_START:
        /* Start-of-datastream actions: reset appropriate modules */
        reset_input_controller(cinfo);
        /* Initialize application's data source module */
        init_source (cinfo);
        cinfo.global_state = DSTATE_INHEADER;
        /*FALLTHROUGH*/
    case DSTATE_INHEADER:
        retcode = consume_input(cinfo);
        if (retcode is JPEG_REACHED_SOS) { /* Found SOS, prepare to decompress */
            /* Set up default parameters based on header data */
            default_decompress_parms(cinfo);
            /* Set global state: ready for start_decompress */
            cinfo.global_state = DSTATE_READY;
        }
        break;
    case DSTATE_READY:
        /* Can't advance past first SOS until start_decompress is called */
        retcode = JPEG_REACHED_SOS;
        break;
    case DSTATE_PRELOAD:
    case DSTATE_PRESCAN:
    case DSTATE_SCANNING:
    case DSTATE_RAW_OK:
    case DSTATE_BUFIMAGE:
    case DSTATE_BUFPOST:
    case DSTATE_STOPPING:
        retcode = consume_input (cinfo);
        break;
    default:
        error();
//      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo.global_state);
    }
    return retcode;
}


static void jpeg_abort (jpeg_decompress_struct cinfo) {
//  int pool;
//
//  /* Releasing pools in reverse order might help avoid fragmentation
//   * with some (brain-damaged) malloc libraries.
//   */
//  for (pool = JPOOL_NUMPOOLS-1; pool > JPOOL_PERMANENT; pool--) {
//      (*cinfo.mem.free_pool) (cinfo, pool);
//  }

    /* Reset overall state for possible reuse of object */
    if (cinfo.is_decompressor) {
        cinfo.global_state = DSTATE_START;
        /* Try to keep application from accessing now-deleted marker list.
         * A bit kludgy to do it here, but this is the most central place.
         */
//      ((j_decompress_ptr) cinfo).marker_list = null;
    } else {
        cinfo.global_state = CSTATE_START;
    }
}


static bool isFileFormat(LEDataInputStream stream) {
    try {
        byte[] buffer = new byte[2];
        stream.read(buffer);
        stream.unread(buffer);
        return (buffer[0] & 0xFF) is 0xFF && (buffer[1] & 0xFF) is M_SOI;
    } catch (Exception e) {
        return false;
    }
}

static ImageData[] loadFromByteStream(InputStream inputStream, ImageLoader loader) {
    jpeg_decompress_struct cinfo = new jpeg_decompress_struct();
    cinfo.inputStream = inputStream;
    jpeg_create_decompress(cinfo);
    jpeg_read_header(cinfo, true);
    cinfo.buffered_image = cinfo.progressive_mode && loader.hasListeners();
    jpeg_start_decompress(cinfo);
    PaletteData palette = null;
    switch (cinfo.out_color_space) {
        case JCS_RGB:
            palette = new PaletteData(0xFF, 0xFF00, 0xFF0000);
            break;
        case JCS_GRAYSCALE:
            RGB[] colors = new RGB[256];
            for (int i = 0; i < colors.length; i++) {
                colors[i] = new RGB(i, i, i);
            }
            palette = new PaletteData(colors);
            break;
        default:
            error();
    }
    int scanlinePad = 4;
    int row_stride = (((cinfo.output_width * cinfo.out_color_components * 8 + 7) / 8) + (scanlinePad - 1)) / scanlinePad * scanlinePad;
    byte[][] buffer = new byte[][]( 1, row_stride );
    byte[] data = new byte[row_stride * cinfo.output_height];
    ImageData imageData = ImageData.internal_new(
            cinfo.output_width, cinfo.output_height, palette.isDirect ? 24 : 8, palette, scanlinePad, data,
            0, null, null, -1, -1, SWT.IMAGE_JPEG, 0, 0, 0, 0);
    if (cinfo.buffered_image) {
        bool done;
        do {
            int incrementCount = cinfo.input_scan_number - 1;
            jpeg_start_output(cinfo, cinfo.input_scan_number);
            while (cinfo.output_scanline < cinfo.output_height) {
                int offset = row_stride * cinfo.output_scanline;
                jpeg_read_scanlines(cinfo, buffer, 1);
                System.arraycopy(buffer[0], 0, data, offset, row_stride);
            }
            jpeg_finish_output(cinfo);
            loader.notifyListeners(new ImageLoaderEvent(loader, cast(ImageData)imageData.clone(), incrementCount, done = jpeg_input_complete(cinfo)));
        } while (!done);
    } else {
        while (cinfo.output_scanline < cinfo.output_height) {
            int offset = row_stride * cinfo.output_scanline;
            jpeg_read_scanlines(cinfo, buffer, 1);
            System.arraycopy(buffer[0], 0, data, offset, row_stride);
        }
    }
    jpeg_finish_decompress(cinfo);
    jpeg_destroy_decompress(cinfo);
    return [imageData];
}

}