text: /* $Header: /home/mguthaus/.cvsroot/mibench/consumer/tiff-v3.5.4/libtiff/tif_packbits.c,v 1.1.1.1 2000/11/06 19:52:27 mguthaus Exp $ */
  
  /*
   * Copyright (c) 1988-1997 Sam Leffler
   * Copyright (c) 1991-1997 Silicon Graphics, Inc.
   *
   * Permission to use, copy, modify, distribute, and sell this software and 
   * its documentation for any purpose is hereby granted without fee, provided
   * that (i) the above copyright notices and this permission notice appear in
   * all copies of the software and related documentation, and (ii) the names of
   * Sam Leffler and Silicon Graphics may not be used in any advertising or
   * publicity relating to the software without the specific, prior written
   * permission of Sam Leffler and Silicon Graphics.
   * 
   * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 
   * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 
   * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  
   * 
   * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
   * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
   * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
   * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF 
   * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 
   * OF THIS SOFTWARE.
   */
  
  #include "tiffiop.h"
  #ifdef PACKBITS_SUPPORT
  /*
   * TIFF Library.
   *
   * PackBits Compression Algorithm Support
   */
  #include <assert.h>
  #include <stdio.h>
  
  static int
  PackBitsPreEncode(TIFF* tif, tsample_t s)
  {
  	(void) s;
  	/*
  	 * Calculate the scanline/tile-width size in bytes.
  	 */
  	if (isTiled(tif))
  		tif->tif_data = (tidata_t) TIFFTileRowSize(tif);
  	else
  		tif->tif_data = (tidata_t) TIFFScanlineSize(tif);
  	return (1);
  }
  
  /*
   * NB: tidata is the type representing *(tidata_t);
   *     if tidata_t is made signed then this type must
   *     be adjusted accordingly.
   */
  typedef unsigned char tidata;
  
  /*
   * Encode a run of pixels.
   */
  static int
  PackBitsEncode(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
  {
  	u_char* bp = (u_char*) buf;
  	tidata_t op, ep, lastliteral;
  	long n, slop;
  	int b;
  	enum { BASE, LITERAL, RUN, LITERAL_RUN } state;
  
  	(void) s;
  	op = tif->tif_rawcp;
  	ep = tif->tif_rawdata + tif->tif_rawdatasize;
  	state = BASE;
  	lastliteral = 0;
  	while (cc > 0) {
  		/*
  		 * Find the longest string of identical bytes.
  		 */
  		b = *bp++, cc--, n = 1;
  		for (; cc > 0 && b == *bp; cc--, bp++)
  			n++;
  	again:
  		if (op + 2 >= ep) {		/* insure space for new data */
  			/*
  			 * Be careful about writing the last
  			 * literal.  Must write up to that point
  			 * and then copy the remainder to the
  			 * front of the buffer.
  			 */
  			if (state == LITERAL || state == LITERAL_RUN) {
  				slop = op - lastliteral;
  				tif->tif_rawcc += lastliteral - tif->tif_rawcp;
  				if (!TIFFFlushData1(tif))
  					return (-1);
  				op = tif->tif_rawcp;
  				while (slop-- > 0)
  					*op++ = *lastliteral++;
  				lastliteral = tif->tif_rawcp;
  			} else {
  				tif->tif_rawcc += op - tif->tif_rawcp;
  				if (!TIFFFlushData1(tif))
  					return (-1);
  				op = tif->tif_rawcp;
  			}
  		}
  		switch (state) {
  		case BASE:		/* initial state, set run/literal */
  			if (n > 1) {
  				state = RUN;
  				if (n > 128) {
  					*op++ = (tidata) -127;
  					*op++ = b;
  					n -= 128;
  					goto again;
  				}
  				*op++ = (tidataval_t)(-(n-1));
  				*op++ = b;
  			} else {
  				lastliteral = op;
  				*op++ = 0;
  				*op++ = b;
  				state = LITERAL;
  			}
  			break;
  		case LITERAL:		/* last object was literal string */
  			if (n > 1) {
  				state = LITERAL_RUN;
  				if (n > 128) {
  					*op++ = (tidata) -127;
  					*op++ = b;
  					n -= 128;
  					goto again;
  				}
  				*op++ = (tidataval_t)(-(n-1));	/* encode run */
  				*op++ = b;
  			} else {			/* extend literal */
  				if (++(*lastliteral) == 127)
  					state = BASE;
  				*op++ = b;
  			}
  			break;
  		case RUN:		/* last object was run */
  			if (n > 1) {
  				if (n > 128) {
  					*op++ = (tidata) -127;
  					*op++ = b;
  					n -= 128;
  					goto again;
  				}
  				*op++ = (tidataval_t)(-(n-1));
  				*op++ = b;
  			} else {
  				lastliteral = op;
  				*op++ = 0;
  				*op++ = b;
  				state = LITERAL;
  			}
  			break;
  		case LITERAL_RUN:	/* literal followed by a run */
  			/*
  			 * Check to see if previous run should
  			 * be converted to a literal, in which
  			 * case we convert literal-run-literal
  			 * to a single literal.
  			 */
  			if (n == 1 && op[-2] == (tidata) -1 &&
  			    *lastliteral < 126) {
  				state = (((*lastliteral) += 2) == 127 ?
  				    BASE : LITERAL);
  				op[-2] = op[-1];	/* replicate */
  			} else
  				state = RUN;
  			goto again;
  		}
  	}
  	tif->tif_rawcc += op - tif->tif_rawcp;
  	tif->tif_rawcp = op;
  	return (1);
  }
  
  /*
   * Encode a rectangular chunk of pixels.  We break it up
   * into row-sized pieces to insure that encoded runs do
   * not span rows.  Otherwise, there can be problems with
   * the decoder if data is read, for example, by scanlines
   * when it was encoded by strips.
   */
  static int
  PackBitsEncodeChunk(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
  {
  	tsize_t rowsize = (tsize_t) tif->tif_data;
  
  	assert(rowsize > 0);
  	while ((long)cc > 0) {
  		if (PackBitsEncode(tif, bp, rowsize, s) < 0)
  			return (-1);
  		bp += rowsize;
  		cc -= rowsize;
  	}
  	return (1);
  }
  
  static int
  PackBitsDecode(TIFF* tif, tidata_t op, tsize_t occ, tsample_t s)
  {
  	char *bp;
  	tsize_t cc;
  	long n;
  	int b;
  
  	(void) s;
  	bp = (char*) tif->tif_rawcp;
  	cc = tif->tif_rawcc;
  	while (cc > 0 && (long)occ > 0) {
  		n = (long) *bp++, cc--;
  		/*
  		 * Watch out for compilers that
  		 * don't sign extend chars...
  		 */
  		if (n >= 128)
  			n -= 256;
  		if (n < 0) {		/* replicate next byte -n+1 times */
  			if (n == -128)	/* nop */
  				continue;
  			n = -n + 1;
  			occ -= n;
  			b = *bp++, cc--;
  			while (n-- > 0)
  				*op++ = b;
  		} else {		/* copy next n+1 bytes literally */
  			_TIFFmemcpy(op, bp, ++n);
  			op += n; occ -= n;
  			bp += n; cc -= n;
  		}
  	}
  	tif->tif_rawcp = (tidata_t) bp;
  	tif->tif_rawcc = cc;
  	if (occ > 0) {
  		TIFFError(tif->tif_name,
  		    "PackBitsDecode: Not enough data for scanline %ld",
  		    (long) tif->tif_row);
  		return (0);
  	}
  	/* check for buffer overruns? */
  	return (1);
  }
  
  int
  TIFFInitPackBits(TIFF* tif, int scheme)
  {
  	(void) scheme;
  	tif->tif_decoderow = PackBitsDecode;
  	tif->tif_decodestrip = PackBitsDecode;
  	tif->tif_decodetile = PackBitsDecode;
  	tif->tif_preencode = PackBitsPreEncode;
  	tif->tif_encoderow = PackBitsEncode;
  	tif->tif_encodestrip = PackBitsEncodeChunk;
  	tif->tif_encodetile = PackBitsEncodeChunk;
  	return (1);
  }
  #endif /* PACKBITS_SUPPORT */
  