1 /* $Id: tif_packbits.c,v 1.13.2.2 2010-06-08 18:50:42 bfriesen Exp $ */
4 * Copyright (c) 1988-1997 Sam Leffler
5 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
7 * Permission to use, copy, modify, distribute, and sell this software and
8 * its documentation for any purpose is hereby granted without fee, provided
9 * that (i) the above copyright notices and this permission notice appear in
10 * all copies of the software and related documentation, and (ii) the names of
11 * Sam Leffler and Silicon Graphics may not be used in any advertising or
12 * publicity relating to the software without the specific, prior written
13 * permission of Sam Leffler and Silicon Graphics.
15 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
17 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
19 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
20 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
21 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
22 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
23 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
28 #ifdef PACKBITS_SUPPORT
32 * PackBits Compression Algorithm Support
37 PackBitsPreEncode(TIFF* tif, tsample_t s)
41 if (!(tif->tif_data = (tidata_t)_TIFFmalloc(sizeof(tsize_t))))
44 * Calculate the scanline/tile-width size in bytes.
47 *(tsize_t*)tif->tif_data = TIFFTileRowSize(tif);
49 *(tsize_t*)tif->tif_data = TIFFScanlineSize(tif);
54 PackBitsPostEncode(TIFF* tif)
57 _TIFFfree(tif->tif_data);
62 * NB: tidata is the type representing *(tidata_t);
63 * if tidata_t is made signed then this type must
64 * be adjusted accordingly.
66 typedef unsigned char tidata;
69 * Encode a run of pixels.
72 PackBitsEncode(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
74 unsigned char* bp = (unsigned char*) buf;
75 tidata_t op, ep, lastliteral;
78 enum { BASE, LITERAL, RUN, LITERAL_RUN } state;
82 ep = tif->tif_rawdata + tif->tif_rawdatasize;
87 * Find the longest string of identical bytes.
89 b = *bp++, cc--, n = 1;
90 for (; cc > 0 && b == *bp; cc--, bp++)
93 if (op + 2 >= ep) { /* insure space for new data */
95 * Be careful about writing the last
96 * literal. Must write up to that point
97 * and then copy the remainder to the
98 * front of the buffer.
100 if (state == LITERAL || state == LITERAL_RUN) {
101 slop = op - lastliteral;
102 tif->tif_rawcc += lastliteral - tif->tif_rawcp;
103 if (!TIFFFlushData1(tif))
107 *op++ = *lastliteral++;
108 lastliteral = tif->tif_rawcp;
110 tif->tif_rawcc += op - tif->tif_rawcp;
111 if (!TIFFFlushData1(tif))
117 case BASE: /* initial state, set run/literal */
121 *op++ = (tidata) -127;
122 *op++ = (tidataval_t) b;
126 *op++ = (tidataval_t)(-(n-1));
127 *op++ = (tidataval_t) b;
131 *op++ = (tidataval_t) b;
135 case LITERAL: /* last object was literal string */
139 *op++ = (tidata) -127;
140 *op++ = (tidataval_t) b;
144 *op++ = (tidataval_t)(-(n-1)); /* encode run */
145 *op++ = (tidataval_t) b;
146 } else { /* extend literal */
147 if (++(*lastliteral) == 127)
149 *op++ = (tidataval_t) b;
152 case RUN: /* last object was run */
155 *op++ = (tidata) -127;
156 *op++ = (tidataval_t) b;
160 *op++ = (tidataval_t)(-(n-1));
161 *op++ = (tidataval_t) b;
165 *op++ = (tidataval_t) b;
169 case LITERAL_RUN: /* literal followed by a run */
171 * Check to see if previous run should
172 * be converted to a literal, in which
173 * case we convert literal-run-literal
174 * to a single literal.
176 if (n == 1 && op[-2] == (tidata) -1 &&
177 *lastliteral < 126) {
178 state = (((*lastliteral) += 2) == 127 ?
180 op[-2] = op[-1]; /* replicate */
186 tif->tif_rawcc += op - tif->tif_rawcp;
192 * Encode a rectangular chunk of pixels. We break it up
193 * into row-sized pieces to insure that encoded runs do
194 * not span rows. Otherwise, there can be problems with
195 * the decoder if data is read, for example, by scanlines
196 * when it was encoded by strips.
199 PackBitsEncodeChunk(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
201 tsize_t rowsize = *(tsize_t*)tif->tif_data;
203 while ((long)cc > 0) {
209 if (PackBitsEncode(tif, bp, chunk, s) < 0)
218 PackBitsDecode(TIFF* tif, tidata_t op, tsize_t occ, tsample_t s)
226 bp = (char*) tif->tif_rawcp;
228 while (cc > 0 && (long)occ > 0) {
229 n = (long) *bp++, cc--;
231 * Watch out for compilers that
232 * don't sign extend chars...
236 if (n < 0) { /* replicate next byte -n+1 times */
237 if (n == -128) /* nop */
242 TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
243 "PackBitsDecode: discarding %ld bytes "
244 "to avoid buffer overrun",
251 *op++ = (tidataval_t) b;
252 } else { /* copy next n+1 bytes literally */
255 TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
256 "PackBitsDecode: discarding %ld bytes "
257 "to avoid buffer overrun",
261 _TIFFmemcpy(op, bp, ++n);
266 tif->tif_rawcp = (tidata_t) bp;
269 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
270 "PackBitsDecode: Not enough data for scanline %ld",
271 (long) tif->tif_row);
278 TIFFInitPackBits(TIFF* tif, int scheme)
281 tif->tif_decoderow = PackBitsDecode;
282 tif->tif_decodestrip = PackBitsDecode;
283 tif->tif_decodetile = PackBitsDecode;
284 tif->tif_preencode = PackBitsPreEncode;
285 tif->tif_postencode = PackBitsPostEncode;
286 tif->tif_encoderow = PackBitsEncode;
287 tif->tif_encodestrip = PackBitsEncodeChunk;
288 tif->tif_encodetile = PackBitsEncodeChunk;
291 #endif /* PACKBITS_SUPPORT */
293 /* vim: set ts=8 sts=8 sw=8 noet: */