/*******************************************************************************
 * Copyright (c) 2000, 2003 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
 *******************************************************************************/
module dwt.internal.image;

import dwt.DWT;

/*
* Decoder for 
* - CCITT Group 3 1-Dimensional Modified Huffman run length encoding
*   (TIFF compression type 2)
* - CCITT T.4 bi-level encoding 1D
*   (TIFF compression type 3 option 1D) 
*/
final class TIFFModifiedHuffmanCodec {
    static final short[][][] BLACK_CODE = {
        /* 2 bits  */
        {{2, 3}, {3, 2}},
        /* 3 bits  */
        {{2, 1}, {3, 4}},
        /* 4 bits  */
        {{2, 6}, {3, 5}},
        /* 5 bits  */
        {{3, 7}},
        /* 6 bits  */
        {{4, 9}, {5, 8}},
        /* 7 bits  */
        {{4, 10}, {5, 11}, {7, 12}},
        /* 8 bits  */
        {{4, 13}, {7, 14}},
        /* 9 bits  */
        {{24, 15}},
        /* 10 bits */
        {{8, 18}, {15, 64}, {23, 16}, {24, 17}, {55, 0}},
        /* 11 bits */
        {/* EOL */{0, -1}, {8, 1792}, {23, 24}, {24, 25}, {40, 23}, {55, 22}, {103, 19},
        {104, 20}, {108, 21}, {12, 1856}, {13, 1920}},
        /* 12 bits */
        {{18, 1984}, {19, 2048}, {20, 2112}, {21, 2176}, {22, 2240}, {23, 2304},
        {28, 2368}, {29, 2432}, {30, 2496}, {31, 2560}, {36, 52}, {39, 55}, {40, 56},
        {43, 59}, {44, 60}, {51, 320}, {52, 384}, {53, 448}, {55, 53}, {56, 54}, {82, 50},
        {83, 51}, {84, 44}, {85, 45}, {86, 46}, {87, 47}, {88, 57}, {89, 58}, {90, 61},
        {91, 256}, {100, 48}, {101, 49}, {102, 62}, {103, 63}, {104, 30}, {105, 31},
        {106, 32}, {107, 33}, {108, 40}, {109, 41}, {200, 128}, {201, 192}, {202, 26},
        {203, 27}, {204, 28}, {205, 29}, {210, 34}, {211, 35}, {212, 36}, {213, 37},
        {214, 38}, {215, 39}, {218, 42}, {219, 43}},
        /* 13 bits */
        {{74, 640}, {75, 704}, {76, 768}, {77, 832}, {82, 1280}, {83, 1344}, {84, 1408},
        {85, 1472}, {90, 1536}, {91, 1600}, {100, 1664}, {101, 1728}, {108, 512},
        {109, 576}, {114, 896}, {115, 960}, {116, 1024}, {117, 1088}, {118, 1152},
        {119, 1216}}
    };

    static final short[][][] WHITE_CODE = {
        /* 4 bits */
        {{7, 2}, {8, 3}, {11, 4}, {12, 5}, {14, 6}, {15, 7}},
        /* 5 bits */
        {{7, 10}, {8, 11}, {18, 128}, {19, 8}, {20, 9}, {27, 64}},
        /* 6 bits */
        {{3, 13}, {7, 1}, {8, 12}, {23, 192}, {24, 1664}, {42, 16}, {43, 17}, {52, 14},
        {53, 15}},
        /* 7 bits */
        {{3, 22}, {4, 23}, {8, 20}, {12, 19}, {19, 26}, {23, 21}, {24, 28}, {36, 27},
        {39, 18}, {40, 24}, {43, 25}, {55, 256}},
        /* 8 bits */
        {{2, 29}, {3, 30}, {4, 45}, {5, 46}, {10, 47}, {11, 48}, {18, 33}, {19, 34},
        {20, 35}, {21, 36}, {22, 37}, {23, 38}, {26, 31}, {27, 32}, {36, 53}, {37, 54},
        {40, 39}, {41, 40}, {42, 41}, {43, 42}, {44, 43}, {45, 44}, {50, 61}, {51, 62},
        {52, 63}, {53, 0}, {54, 320}, {55, 384}, {74, 59}, {75, 60}, {82, 49}, {83, 50},
        {84, 51}, {85, 52}, {88, 55}, {89, 56}, {90, 57}, {91, 58}, {100, 448},
        {101, 512}, {103, 640}, {104, 576}},
        /* 9 bits */
        {{152, 1472}, {153, 1536}, {154, 1600}, {155, 1728}, {204, 704}, {205, 768},
        {210, 832}, {211, 896}, {212, 960}, {213, 1024}, {214, 1088}, {215, 1152},
        {216, 1216}, {217, 1280}, {218, 1344}, {219, 1408}},
        /* 10 bits */
        {},
        /* 11 bits */
        {{8, 1792}, {12, 1856}, {13, 1920}},
        /* 12 bits */
        {/* EOL */{1, -1}, {18, 1984}, {19, 2048}, {20, 2112}, {21, 2176}, {22, 2240}, {23, 2304},
        {28, 2368}, {29, 2432}, {30, 2496}, {31, 2560}}
    };
    
    static final int BLACK_MIN_BITS = 2;
    static final int WHITE_MIN_BITS = 4;

    bool isWhite;
    int whiteValue = 0;
    int blackValue = 1;
    byte[] src;
    byte[] dest;
    int byteOffsetSrc = 0;
    int bitOffsetSrc = 0;
    int byteOffsetDest = 0;
    int bitOffsetDest = 0;
    int code = 0;
    int nbrBits = 0;
    /* nbr of bytes per row */
    int rowSize;

public int decode(byte[] src, byte[] dest, int offsetDest, int rowSize, int nRows) {
    this.src = src;
    this.dest = dest;
    this.rowSize = rowSize;
    byteOffsetSrc = 0;
    bitOffsetSrc = 0;
    byteOffsetDest = offsetDest;
    bitOffsetDest = 0;
    int cnt = 0;
    while (cnt < nRows && decodeRow()) {
        cnt++;
        /* byte aligned */
        if (bitOffsetDest > 0) {
            byteOffsetDest++;
            bitOffsetDest = 0; 
        }
    }
    return byteOffsetDest - offsetDest;
}

bool decodeRow() {
    isWhite = true;
    int n = 0;
    while (n < rowSize) {
        int runLength = decodeRunLength();
        if (runLength < 0) return false;
        n += runLength;
        setNextBits(isWhite ? whiteValue : blackValue, runLength);
        isWhite = !isWhite;
    }
    return true;
}

int decodeRunLength() {
    int runLength = 0;
    int partialRun = 0;
    short[][][] huffmanCode = isWhite ? WHITE_CODE : BLACK_CODE;
    while (true) {
        bool found = false;
        nbrBits = isWhite ? WHITE_MIN_BITS : BLACK_MIN_BITS;
        code = getNextBits(nbrBits);
        for (int i = 0; i < huffmanCode.length; i++) {
            for (int j = 0; j < huffmanCode[i].length; j++) {
                if (huffmanCode[i][j][0] is code) {
                    found = true;
                    partialRun = huffmanCode[i][j][1];
                    if (partialRun is -1) {
                        /* Stop when reaching final EOL on last byte */
                        if (byteOffsetSrc is src.length - 1) return -1;
                        /* Group 3 starts each row with an EOL - ignore it */
                    } else {
                        runLength += partialRun;
                        if (partialRun < 64) return runLength;
                    }
                    break;
                }
            }
            if (found) break;
            code = code << 1 | getNextBit();
        }
        if (!found) DWT.error(DWT.ERROR_INVALID_IMAGE);          
    }
}

int getNextBit() {
    int value = (src[byteOffsetSrc] >>> (7 - bitOffsetSrc)) & 0x1;
    bitOffsetSrc++;
    if (bitOffsetSrc > 7) {
        byteOffsetSrc++;
        bitOffsetSrc = 0;
    }
    return value;
}

int getNextBits(int cnt) {
    int value = 0;
    for (int i = 0; i < cnt; i++) {
        value = value << 1 | getNextBit();
    }
    return value;
}

void setNextBits(int value, int cnt) {
    int n = cnt;
    while (bitOffsetDest > 0 && bitOffsetDest <= 7 && n > 0) {
        dest[byteOffsetDest] = value is 1 ?
            cast(byte)(dest[byteOffsetDest] | (1 << (7 - bitOffsetDest))) :
            cast(byte)(dest[byteOffsetDest] & ~(1 << (7 - bitOffsetDest)));
        n--;
        bitOffsetDest++; 
    }
    if (bitOffsetDest is 8) {
        byteOffsetDest++;
        bitOffsetDest = 0;
    }
    while (n >= 8) {
        dest[byteOffsetDest++] = cast(byte) (value is 1 ? 0xFF : 0);
        n -= 8;
    }
    while (n > 0) {
        dest[byteOffsetDest] = value is 1 ?
            cast(byte)(dest[byteOffsetDest] | (1 << (7 - bitOffsetDest))) :
            cast(byte)(dest[byteOffsetDest] & ~(1 << (7 - bitOffsetDest)));
        n--;
        bitOffsetDest++;        
    }   
}

}