Blame libtiff/tif_packbits.c

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/* $Id: tif_packbits.c,v 1.26 2017-05-14 02:26:07 erouault Exp $ */
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/*
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 * Copyright (c) 1988-1997 Sam Leffler
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 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
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 *
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 * Permission to use, copy, modify, distribute, and sell this software and 
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 * its documentation for any purpose is hereby granted without fee, provided
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 * that (i) the above copyright notices and this permission notice appear in
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 * all copies of the software and related documentation, and (ii) the names of
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 * Sam Leffler and Silicon Graphics may not be used in any advertising or
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 * publicity relating to the software without the specific, prior written
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 * permission of Sam Leffler and Silicon Graphics.
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 * 
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 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 
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 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 
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 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  
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 * 
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 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
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 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
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 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
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 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF 
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 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 
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 * OF THIS SOFTWARE.
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 */
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#include "tiffiop.h"
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#ifdef PACKBITS_SUPPORT
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/*
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 * TIFF Library.
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 *
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 * PackBits Compression Algorithm Support
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 */
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#include <stdio.h>
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static int
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PackBitsPreEncode(TIFF* tif, uint16 s)
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{
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	(void) s;
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        tif->tif_data = (uint8*)_TIFFmalloc(sizeof(tmsize_t));
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	if (tif->tif_data == NULL)
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		return (0);
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	/*
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	 * Calculate the scanline/tile-width size in bytes.
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	 */
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	if (isTiled(tif))
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		*(tmsize_t*)tif->tif_data = TIFFTileRowSize(tif);
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	else
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		*(tmsize_t*)tif->tif_data = TIFFScanlineSize(tif);
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	return (1);
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}
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static int
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PackBitsPostEncode(TIFF* tif)
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{
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        if (tif->tif_data)
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            _TIFFfree(tif->tif_data);
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	return (1);
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}
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/*
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 * Encode a run of pixels.
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 */
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static int
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PackBitsEncode(TIFF* tif, uint8* buf, tmsize_t cc, uint16 s)
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{
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	unsigned char* bp = (unsigned char*) buf;
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	uint8* op;
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	uint8* ep;
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	uint8* lastliteral;
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	long n, slop;
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	int b;
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	enum { BASE, LITERAL, RUN, LITERAL_RUN } state;
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	(void) s;
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	op = tif->tif_rawcp;
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	ep = tif->tif_rawdata + tif->tif_rawdatasize;
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	state = BASE;
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	lastliteral = 0;
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	while (cc > 0) {
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		/*
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		 * Find the longest string of identical bytes.
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		 */
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		b = *bp++;
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		cc--;
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		n = 1;
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		for (; cc > 0 && b == *bp; cc--, bp++)
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			n++;
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	again:
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		if (op + 2 >= ep) {		/* insure space for new data */
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			/*
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			 * Be careful about writing the last
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			 * literal.  Must write up to that point
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			 * and then copy the remainder to the
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			 * front of the buffer.
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			 */
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			if (state == LITERAL || state == LITERAL_RUN) {
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				slop = (long)(op - lastliteral);
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				tif->tif_rawcc += (tmsize_t)(lastliteral - tif->tif_rawcp);
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				if (!TIFFFlushData1(tif))
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					return (0);
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				op = tif->tif_rawcp;
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				while (slop-- > 0)
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					*op++ = *lastliteral++;
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				lastliteral = tif->tif_rawcp;
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			} else {
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				tif->tif_rawcc += (tmsize_t)(op - tif->tif_rawcp);
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				if (!TIFFFlushData1(tif))
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					return (0);
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				op = tif->tif_rawcp;
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			}
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		}
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		switch (state) {
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		case BASE:		/* initial state, set run/literal */
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			if (n > 1) {
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				state = RUN;
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				if (n > 128) {
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					*op++ = (uint8) -127;
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					*op++ = (uint8) b;
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					n -= 128;
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					goto again;
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				}
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				*op++ = (uint8)(-(n-1));
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				*op++ = (uint8) b;
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			} else {
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				lastliteral = op;
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				*op++ = 0;
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				*op++ = (uint8) b;
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				state = LITERAL;
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			}
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			break;
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		case LITERAL:		/* last object was literal string */
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			if (n > 1) {
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				state = LITERAL_RUN;
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				if (n > 128) {
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					*op++ = (uint8) -127;
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					*op++ = (uint8) b;
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					n -= 128;
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					goto again;
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				}
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				*op++ = (uint8)(-(n-1));	/* encode run */
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				*op++ = (uint8) b;
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			} else {			/* extend literal */
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				if (++(*lastliteral) == 127)
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					state = BASE;
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				*op++ = (uint8) b;
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			}
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			break;
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		case RUN:		/* last object was run */
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			if (n > 1) {
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				if (n > 128) {
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					*op++ = (uint8) -127;
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					*op++ = (uint8) b;
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					n -= 128;
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					goto again;
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				}
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				*op++ = (uint8)(-(n-1));
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				*op++ = (uint8) b;
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			} else {
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				lastliteral = op;
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				*op++ = 0;
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				*op++ = (uint8) b;
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				state = LITERAL;
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			}
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			break;
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		case LITERAL_RUN:	/* literal followed by a run */
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			/*
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			 * Check to see if previous run should
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			 * be converted to a literal, in which
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			 * case we convert literal-run-literal
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			 * to a single literal.
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			 */
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			if (n == 1 && op[-2] == (uint8) -1 &&
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			    *lastliteral < 126) {
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				state = (((*lastliteral) += 2) == 127 ?
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				    BASE : LITERAL);
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				op[-2] = op[-1];	/* replicate */
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			} else
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				state = RUN;
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			goto again;
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		}
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	}
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	tif->tif_rawcc += (tmsize_t)(op - tif->tif_rawcp);
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	tif->tif_rawcp = op;
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	return (1);
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}
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/*
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 * Encode a rectangular chunk of pixels.  We break it up
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 * into row-sized pieces to insure that encoded runs do
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 * not span rows.  Otherwise, there can be problems with
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 * the decoder if data is read, for example, by scanlines
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 * when it was encoded by strips.
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 */
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static int
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PackBitsEncodeChunk(TIFF* tif, uint8* bp, tmsize_t cc, uint16 s)
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{
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	tmsize_t rowsize = *(tmsize_t*)tif->tif_data;
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	while (cc > 0) {
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		tmsize_t chunk = rowsize;
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		if( cc < chunk )
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		    chunk = cc;
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		if (PackBitsEncode(tif, bp, chunk, s) < 0)
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		    return (-1);
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		bp += chunk;
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		cc -= chunk;
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	}
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	return (1);
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}
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static int
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PackBitsDecode(TIFF* tif, uint8* op, tmsize_t occ, uint16 s)
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{
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	static const char module[] = "PackBitsDecode";
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	char *bp;
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	tmsize_t cc;
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	long n;
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	int b;
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	(void) s;
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	bp = (char*) tif->tif_rawcp;
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	cc = tif->tif_rawcc;
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	while (cc > 0 && occ > 0) {
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		n = (long) *bp++;
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		cc--;
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		/*
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		 * Watch out for compilers that
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		 * don't sign extend chars...
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		 */
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		if (n >= 128)
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			n -= 256;
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		if (n < 0) {		/* replicate next byte -n+1 times */
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			if (n == -128)	/* nop */
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				continue;
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			n = -n + 1;
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			if( occ < (tmsize_t)n )
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			{
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				TIFFWarningExt(tif->tif_clientdata, module,
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				    "Discarding %lu bytes to avoid buffer overrun",
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				    (unsigned long) ((tmsize_t)n - occ));
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				n = (long)occ;
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			}
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			if( cc == 0 )
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			{
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				TIFFWarningExt(tif->tif_clientdata, module,
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					       "Terminating PackBitsDecode due to lack of data.");
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				break;
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			}
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			occ -= n;
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			b = *bp++;
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			cc--;
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			while (n-- > 0)
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				*op++ = (uint8) b;
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		} else {		/* copy next n+1 bytes literally */
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			if (occ < (tmsize_t)(n + 1))
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			{
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				TIFFWarningExt(tif->tif_clientdata, module,
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				    "Discarding %lu bytes to avoid buffer overrun",
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				    (unsigned long) ((tmsize_t)n - occ + 1));
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				n = (long)occ - 1;
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			}
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			if (cc < (tmsize_t) (n+1)) 
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			{
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				TIFFWarningExt(tif->tif_clientdata, module,
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					       "Terminating PackBitsDecode due to lack of data.");
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				break;
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			}
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			_TIFFmemcpy(op, bp, ++n);
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			op += n; occ -= n;
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			bp += n; cc -= n;
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		}
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	}
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	tif->tif_rawcp = (uint8*) bp;
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	tif->tif_rawcc = cc;
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	if (occ > 0) {
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		TIFFErrorExt(tif->tif_clientdata, module,
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		    "Not enough data for scanline %lu",
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		    (unsigned long) tif->tif_row);
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		return (0);
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	}
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	return (1);
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}
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int
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TIFFInitPackBits(TIFF* tif, int scheme)
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{
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	(void) scheme;
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	tif->tif_decoderow = PackBitsDecode;
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	tif->tif_decodestrip = PackBitsDecode;
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	tif->tif_decodetile = PackBitsDecode;
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	tif->tif_preencode = PackBitsPreEncode;
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	tif->tif_postencode = PackBitsPostEncode;
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	tif->tif_encoderow = PackBitsEncode;
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	tif->tif_encodestrip = PackBitsEncodeChunk;
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	tif->tif_encodetile = PackBitsEncodeChunk;
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	return (1);
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}
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#endif /* PACKBITS_SUPPORT */
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/* vim: set ts=8 sts=8 sw=8 noet: */
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/*
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 * Local Variables:
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 * mode: c
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 * c-basic-offset: 8
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 * fill-column: 78
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 * End:
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 */