"

 COPYRIGHT (c) 1991 by Claus Gittinger

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

Object subclass:#ImageReader

	 classVariableNames:'ReverseBits'

	 poolDictionaries:''

	 category:'Graphics-Images support'

!

ImageReader comment:'

COPYRIGHT (c) 1991 by Claus Gittinger

	      All Rights Reserved

'!

!ImageReader primitiveFunctions!

%{

/*

 * ccitt decompression

 */

static short *whiteCountTable;

static char  *whiteShiftTable;

static short *blackCountTable;

static char  *blackShiftTable;

struct ccitt_def {

    unsigned short bits;

    short nBits;

};

static struct ccitt_def 

whiteDef[] = {

    { 0x3500, 8 }, /* 0 */

    { 0x1c00, 6 },

    { 0x7000, 4 },

    { 0x8000, 4 },

    { 0xb000, 4 },

    { 0xc000, 4 },

    { 0xe000, 4 },

    { 0xf000, 4 },

    { 0x9800, 5 },

    { 0xA000, 5 },

    { 0x3800, 5 }, /* 10 */

    { 0x4000, 5 },

    { 0x2000, 6 },

    { 0x0c00, 6 },

    { 0xd000, 6 },

    { 0xd400, 6 },

    { 0xa800, 6 },

    { 0xac00, 6 },

    { 0x4e00, 7 },

    { 0x1800, 7 },

    { 0x1000, 7 }, /* 20 */

    { 0x2e00, 7 },

    { 0x0600, 7 },

    { 0x0800, 7 },

    { 0x5000, 7 },

    { 0x5600, 7 },

    { 0x2600, 7 },

    { 0x4800, 7 },

    { 0x3000, 7 },

    { 0x0200, 8 },

    { 0x0300, 8 }, /* 30 */ 

    { 0x1a00, 8 }, 

    { 0x1b00, 8 }, 

    { 0x1200, 8 }, 

    { 0x1300, 8 }, 

    { 0x1400, 8 }, 

    { 0x1500, 8 }, 

    { 0x1600, 8 }, 

    { 0x1700, 8 }, 

    { 0x2800, 8 }, 

    { 0x2900, 8 }, /* 40 */

    { 0x2a00, 8 }, 

    { 0x2b00, 8 }, 

    { 0x2c00, 8 }, 

    { 0x2d00, 8 }, 

    { 0x0400, 8 }, 

    { 0x0500, 8 }, 

    { 0x0a00, 8 }, 

    { 0x0b00, 8 }, 

    { 0x5200, 8 }, 

    { 0x5300, 8 }, /* 50 */

    { 0x5400, 8 }, 

    { 0x5500, 8 }, 

    { 0x2400, 8 }, 

    { 0x2500, 8 }, 

    { 0x5800, 8 }, 

    { 0x5900, 8 }, 

    { 0x5a00, 8 }, 

    { 0x5b00, 8 }, 

    { 0x4a00, 8 }, 

    { 0x4b00, 8 }, /* 60 */

    { 0x3200, 8 }, 

    { 0x3300, 8 }, 

    { 0x3400, 8 }, 

/* ---------------- */

    { 0xd800, 5 }, /* 64 */

    { 0x9000, 5 }, /* 128 */

    { 0x5c00, 6 }, /* 192 */

    { 0x6e00, 7 }, /* 256 */

    { 0x3600, 8 }, /* 320 */

    { 0x3700, 8 },

    { 0x6400, 8 },

    { 0x6500, 8 },

    { 0x6800, 8 },

    { 0x6700, 8 }, /* 640 */

    { 0x6600, 9 }, /* 704 */

    { 0x6680, 9 },

    { 0x6900, 9 },

    { 0x6980, 9 },

    { 0x6a00, 9 },

    { 0x6a80, 9 },

    { 0x6b00, 9 },

    { 0x6b80, 9 },

    { 0x6c00, 9 },

    { 0x6c80, 9 },

    { 0x6d00, 9 },

    { 0x6d80, 9 },

    { 0x4c00, 9 },

    { 0x4c80, 9 },

    { 0x4d00, 9 }, /* 1600 */

    { 0x6000, 6 }, /* 1664 */

    { 0x4d80, 9 }, /* 1728 */

/* -------------------------------- */

    { 0x0100, 11 }, /* 1792 */

    { 0x0180, 11 },

    { 0x01a0, 11 }, /* 1920 */

    { 0x0120, 12 }, /* 1984 */

    { 0x0130, 12 },

    { 0x0140, 12 },

    { 0x0150, 12 },

    { 0x0160, 12 },

    { 0x0170, 12 },

    { 0x01c0, 12 },

    { 0x01d0, 12 },

    { 0x01e0, 12 },

    { 0x01f0, 12 }, /* 2560 */

/* -------------------------------- */

    { 0x0010, 12 }, /* EOL */

};

static struct ccitt_def 

blackDef[] = {

    { 0x0dc0, 10 }, /* 0 */

    { 0x4000, 3 },

    { 0xc000, 2 },

    { 0x8000, 2 },

    { 0x6000, 3 },

    { 0x3000, 4 },

    { 0x2000, 4 },

    { 0x1800, 5 },

    { 0x1400, 6 },

    { 0x1000, 6 },

    { 0x0800, 7 }, /* 10 */

    { 0x0a00, 7 },

    { 0x0e00, 7 },

    { 0x0400, 8 },

    { 0x0700, 8 },

    { 0x0c00, 9 },

    { 0x05c0, 10 },

    { 0x0600, 10 },

    { 0x0200, 10 },

    { 0x0ce0, 11 },

    { 0x0d00, 11 }, /* 20 */

    { 0x0d80, 11 },

    { 0x06e0, 11 },

    { 0x0500, 11 },

    { 0x02e0, 11 },

    { 0x0300, 11 },

    { 0x0ca0, 12 },

    { 0x0cb0, 12 },

    { 0x0cc0, 12 },

    { 0x0cd0, 12 }, 

    { 0x0680, 12 }, /* 30 */

    { 0x0690, 12 }, 

    { 0x06a0, 12 }, 

    { 0x06b0, 12 }, 

    { 0x0d20, 12 }, 

    { 0x0d30, 12 }, 

    { 0x0d40, 12 }, 

    { 0x0d50, 12 }, 

    { 0x0d60, 12 }, 

    { 0x0d70, 12 },

    { 0x06c0, 12 }, /* 40 */ 

    { 0x06d0, 12 }, 

    { 0x0da0, 12 }, 

    { 0x0db0, 12 }, 

    { 0x0540, 12 }, 

    { 0x0550, 12 }, 

    { 0x0560, 12 }, 

    { 0x0570, 12 }, 

    { 0x0640, 12 }, 

    { 0x0650, 12 },

    { 0x0520, 12 }, /* 50 */ 

    { 0x0530, 12 }, 

    { 0x0240, 12 }, 

    { 0x0370, 12 }, 

    { 0x0380, 12 }, 

    { 0x0270, 12 }, 

    { 0x0280, 12 }, 

    { 0x0580, 12 }, 

    { 0x0590, 12 }, 

    { 0x02b0, 12 },

    { 0x02c0, 12 }, /* 60 */ 

    { 0x05a0, 12 }, 

    { 0x0660, 12 }, 

    { 0x0670, 12 }, 

/* ---------------- */

    { 0x03c0, 10 }, /* 64 */

    { 0x0c80, 12 }, /* 128 */

    { 0x0c90, 12 }, /* 192 */

    { 0x05b0, 12 }, /* 256 */

    { 0x0330, 12 }, /* 320 */

    { 0x0340, 12 },

    { 0x0350, 12 }, /* 448 */

    { 0x0360, 13 }, /* 512 */

    { 0x0368, 13 },

    { 0x0250, 13 }, /* 640 */

    { 0x0258, 13 }, /* 704 */

    { 0x0260, 13 },

    { 0x0268, 13 },

    { 0x0390, 13 },

    { 0x0398, 13 },

    { 0x03a0, 13 },

    { 0x03a8, 13 },

    { 0x03b0, 13 },

    { 0x03b8, 13 },

    { 0x0290, 13 },

    { 0x0298, 13 },

    { 0x02a0, 13 },

    { 0x02a8, 13 },

    { 0x02d0, 13 },

    { 0x02d8, 13 }, /* 1600 */

    { 0x0320, 13 }, /* 1664 */

    { 0x0328, 13 }, /* 1728 */

/* -------------------------------- */

};

static

initCCITTTables() {

    register cnt, bits, value;

    int nBits, index;

    if (whiteCountTable != (short *)0) return;

    whiteCountTable = (short *) malloc(sizeof(short) * 8192);

    if (! whiteCountTable) return;

    whiteShiftTable = (char *) malloc(sizeof(char) * 8192);

    if (! whiteShiftTable) {

	goto fail1;

/*

	free(whiteCountTable); whiteCountTable = (short *)0;

	return;

*/

    }

    blackCountTable = (short *) malloc(sizeof(short) * 8192);

    if (! blackCountTable) {

	goto fail2;

/*

	free(whiteShiftTable); whiteShiftTable = (char *)0;

	free(whiteCountTable); whiteCountTable = (short *)0;

	return;

*/

    }

    blackShiftTable = (char *) malloc(sizeof(char) * 8192);

    if (! blackShiftTable) {

	free(blackCountTable); blackCountTable = (short *)0;

fail2:

	free(whiteShiftTable); whiteShiftTable = (char *)0;

fail1:

	free(whiteCountTable); whiteCountTable = (short *)0;

	return;

    }

    for (index = 0; index < 8192; index++) {

	whiteCountTable[index] = -1;

	blackCountTable[index] = -1;

    }

    for (value = 0; value <= 63; value++) {

	nBits = whiteDef[value].nBits;

	bits = whiteDef[value].bits >> 3;

	for (cnt = 1 << (13 - nBits); cnt; cnt--, bits++) {

	    whiteCountTable[bits] = value;

	    whiteShiftTable[bits] = nBits;

	}

	nBits = blackDef[value].nBits;

	bits = blackDef[value].bits >> 3;

	for (cnt = 1 << (13 - nBits); cnt; cnt--, bits++) {

	    blackCountTable[bits] = value;

	    blackShiftTable[bits] = nBits;

	}

    }

    index = value;

    for (; value <= 1728; value += 64) {

	nBits = whiteDef[index].nBits;

	bits = whiteDef[index].bits >> 3;

	for (cnt = 1 << (13 - nBits); cnt; cnt--, bits++) {

	    whiteCountTable[bits] = value;

	    whiteShiftTable[bits] = nBits;

	}

	nBits = blackDef[index].nBits;

	bits = blackDef[index].bits >> 3;

	for (cnt = 1 << (13 - nBits); cnt; cnt--, bits++) {

	    blackCountTable[bits] = value;

	    blackShiftTable[bits] = nBits;

	}

	index++;

    }

    for (; value <= 2560; value += 64) {

	nBits = whiteDef[index].nBits;

	bits = whiteDef[index].bits >> 3;

	for (cnt = 1 << (13 - nBits); cnt; cnt--, bits++) {

	    whiteCountTable[bits] = value;

	    whiteShiftTable[bits] = nBits;

	    blackCountTable[bits] = value;

	    blackShiftTable[bits] = nBits;

	}

	index++;

    }

}

static short 

leftBits[] = {

     0, 0x80, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC, 0xFE, 0xFF

};

__decodeCCITTgroup3__(from, to, len)

    unsigned char *from;

    register unsigned char *to;

{

    register cnt;

    register short *countPtr;

    register char *shiftPtr;

    unsigned bits, bits13;

    int shift, outCount, nBitsLess13;

    int outBitOffset;

    int nLeft, t;

    if (! whiteCountTable) initCCITTTables();

    if (! whiteCountTable) return 0; /* malloc failed */

    countPtr = whiteCountTable;

    shiftPtr = whiteShiftTable;

    outCount = 0;

    outBitOffset = 0;

    bits = *from++;

    bits = (bits << 8) | *from++;

    nBitsLess13 = 3;

    for (;;) {

	bits13 = (bits >> nBitsLess13) & 0x1FFF;

	cnt = countPtr[bits13];

	if (cnt < 0) return;

	shift = shiftPtr[bits13];

	outCount += cnt;

	if (countPtr == blackCountTable) {

	    /* toggle if it was a terminating code */

	    if (cnt < 64) {

		countPtr = whiteCountTable;

		shiftPtr = whiteShiftTable;

	    }

	    /* draw cnt black bits */

	    if (cnt) {

		if (outBitOffset) {

		    nLeft = 8 - outBitOffset;

		    if (cnt < nLeft) nLeft = cnt;

		    t = leftBits[nLeft] >> outBitOffset;

		    *to |= t;

		    cnt -= nLeft;

		    outBitOffset += nLeft;

		    if (outBitOffset >= 8) {

			to++;

			outBitOffset -= 8;

		    }

		}

		if (cnt > 256) {

		    while ((int)to & 3) {

			*to++ = 0xFF;

			cnt -= 8;

		    }

		    while (cnt >= 32) {

			(*(long *)to) = 0xFFFFFFFF;

			to += 4;

			cnt -= 32;

		    }

		}

		while (cnt >= 8) {

		    *to++ = 0xFF;

		    cnt -= 8;

		}

		*to |= leftBits[cnt];

		outBitOffset += cnt;

	    }

	} else {

	    /* toggle if it was a terminating code */

	    if (cnt < 64) {

		countPtr = blackCountTable;

		shiftPtr = blackShiftTable;

	    }

	    /* skip cnt bits */

	    to += cnt >> 3;

	    outBitOffset += cnt & 7;

	    if (outBitOffset >= 8) {

		to++;

		outBitOffset -= 8;

	    }

	}

	if (outCount >= len) return 1;

	nBitsLess13 -= shift;

	while (nBitsLess13 < 0) {

	    bits = (bits << 8) | *from++;

	    nBitsLess13 += 8;

	}

    }

}

/*

 * LZW decompression

 */

struct buffer {

	struct buffer *prev;

	unsigned char chars[8192 - 4];

};

__decodeLZW__(from, to, inCount)

    unsigned char *from;

    unsigned char *to;

{

    register unsigned code;

    unsigned char **strings;

    short *stringLen;

    struct buffer *scratchBuffer;

    struct buffer *newBuffer;

    unsigned char *scratchPtr;

    int nScratch;

    unsigned nextCode, oldCode;

    register unsigned bits;

    int nBits, mask, shift;

    int i;

    int len;

    int codeLen = 9;

    scratchBuffer = (struct buffer *)malloc(sizeof(struct buffer));

    if (! scratchBuffer) return 0;

    strings = (unsigned char **)malloc(sizeof(unsigned char *) * 4096);

    if (! strings) {

	free(scratchBuffer);

	return 0;

    }

    stringLen = (short *)malloc(sizeof(short) * 4096);

    if (! stringLen) {

	free(strings);

	free(scratchBuffer);

	return 0;

    }

    scratchBuffer->prev = (struct buffer *)0;

    scratchPtr = scratchBuffer->chars;

    nScratch = sizeof(scratchBuffer->chars);

    for (i = 0; i < 256; i++) {

	*scratchPtr = i;

	strings[i] = scratchPtr++;

	stringLen[i] = 1;

    }

    nextCode = 258;

    nScratch -= 256;

    mask = 0x1FF;

    nBits = 0;

    bits = 0;

    while (inCount) {

	/* fetch code */

	while (nBits < codeLen) {

	    bits = (bits<<8) | *from++;

	    inCount--;

	    nBits += 8;

	}

	shift = nBits - codeLen;

	code = (bits >> shift) & mask;

	bits &= ~(mask << shift);

	nBits -= codeLen;

	if (code == 257) break;

	if (code == 256) {

	    if (! inCount)

		break;

	    /* free stuff */

	    while (scratchBuffer->prev) {