/*******************************************************************************
 * 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.TIFFModifiedHuffmanCodec;

import dwt.SWT;

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

	static final short[][][] WHITE_CODE = [
		/* 4 bits */
		[[ cast(short)7, 2], [ cast(short)8, 3], [ cast(short)11, 4], [ cast(short)12, 5], [ cast(short)14, 6], [ cast(short)15, 7]],
		/* 5 bits */
		[[ cast(short)7, 10], [ cast(short)8, 11], [ cast(short)18, 128], [ cast(short)19, 8], [ cast(short)20, 9], [ cast(short)27, 64]],
		/* 6 bits */
		[[ cast(short)3, 13], [ cast(short)7, 1], [ cast(short)8, 12], [ cast(short)23, 192], [ cast(short)24, 1664], [ cast(short)42, 16], [ cast(short)43, 17], [ cast(short)52, 14],
		[ cast(short)53, 15]],
		/* 7 bits */
		[[ cast(short)3, 22], [ cast(short)4, 23], [ cast(short)8, 20], [ cast(short)12, 19], [ cast(short)19, 26], [ cast(short)23, 21], [ cast(short)24, 28], [ cast(short)36, 27],
		[ cast(short)39, 18], [ cast(short)40, 24], [ cast(short)43, 25], [ cast(short)55, 256]],
		/* 8 bits */
		[[ cast(short)2, 29], [ cast(short)3, 30], [ cast(short)4, 45], [ cast(short)5, 46], [ cast(short)10, 47], [ cast(short)11, 48], [ cast(short)18, 33], [ cast(short)19, 34],
		[ cast(short)20, 35], [ cast(short)21, 36], [ cast(short)22, 37], [ cast(short)23, 38], [ cast(short)26, 31], [ cast(short)27, 32], [ cast(short)36, 53], [ cast(short)37, 54],
		[ cast(short)40, 39], [ cast(short)41, 40], [ cast(short)42, 41], [ cast(short)43, 42], [ cast(short)44, 43], [ cast(short)45, 44], [ cast(short)50, 61], [ cast(short)51, 62],
		[ cast(short)52, 63], [ cast(short)53, 0], [ cast(short)54, 320], [ cast(short)55, 384], [ cast(short)74, 59], [ cast(short)75, 60], [ cast(short)82, 49], [ cast(short)83, 50],
		[ cast(short)84, 51], [ cast(short)85, 52], [ cast(short)88, 55], [ cast(short)89, 56], [ cast(short)90, 57], [ cast(short)91, 58], [ cast(short)100, 448],
		[ cast(short)101, 512], [ cast(short)103, 640], [ cast(short)104, 576]],
		/* 9 bits */
		[[ cast(short)152, 1472], [ cast(short)153, 1536], [ cast(short)154, 1600], [ cast(short)155, 1728], [ cast(short)204, 704], [ cast(short)205, 768],
		[ cast(short)210, 832], [ cast(short)211, 896], [ cast(short)212, 960], [ cast(short)213, 1024], [ cast(short)214, 1088], [ cast(short)215, 1152],
		[ cast(short)216, 1216], [ cast(short)217, 1280], [ cast(short)218, 1344], [ cast(short)219, 1408]],
		/* 10 bits */
		[],
		/* 11 bits */
		[[ cast(short)8, 1792], [ cast(short)12, 1856], [ cast(short)13, 1920]],
		/* 12 bits */
		[/* EOL */[ cast(short)1, -1], [ cast(short)18, 1984], [ cast(short)19, 2048], [ cast(short)20, 2112], [ cast(short)21, 2176], [ cast(short)22, 2240], [ cast(short)23, 2304],
		[ cast(short)28, 2368], [ cast(short)29, 2432], [ cast(short)30, 2496], [ cast(short)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] == code) {
					found = true;
					partialRun = huffmanCode[i][j][1];
					if (partialRun == -1) {
						/* Stop when reaching final EOL on last byte */
						if (byteOffsetSrc == 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) SWT.error(SWT.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 == 1 ?
			cast(byte)(dest[byteOffsetDest] | (1 << (7 - bitOffsetDest))) :
			cast(byte)(dest[byteOffsetDest] & ~(1 << (7 - bitOffsetDest)));
		n--;
		bitOffsetDest++;
	}
	if (bitOffsetDest == 8) {
		byteOffsetDest++;
		bitOffsetDest = 0;
	}
	while (n >= 8) {
		dest[byteOffsetDest++] = cast(byte) (value == 1 ? 0xFF : 0);
		n -= 8;
	}
	while (n > 0) {
		dest[byteOffsetDest] = value == 1 ?
			cast(byte)(dest[byteOffsetDest] | (1 << (7 - bitOffsetDest))) :
			cast(byte)(dest[byteOffsetDest] & ~(1 << (7 - bitOffsetDest)));
		n--;
		bitOffsetDest++;
	}
}

}