1/* $Id: tif_packbits.c,v 1.13.2.2 2010-06-08 18:50:42 bfriesen Exp $ */
2
3/*
4 * Copyright (c) 1988-1997 Sam Leffler
5 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
6 *
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.
14 *
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.
18 *
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
24 * OF THIS SOFTWARE.
25 */
26
27#include "tiffiop.h"
28#ifdef PACKBITS_SUPPORT
29/*
30 * TIFF Library.
31 *
32 * PackBits Compression Algorithm Support
33 */
34#include <stdio.h>
35
36static int
37PackBitsPreEncode(TIFF* tif, tsample_t s)
38{
39	(void) s;
40
41        if (!(tif->tif_data = (tidata_t)_TIFFmalloc(sizeof(tsize_t))))
42		return (0);
43	/*
44	 * Calculate the scanline/tile-width size in bytes.
45	 */
46	if (isTiled(tif))
47		*(tsize_t*)tif->tif_data = TIFFTileRowSize(tif);
48	else
49		*(tsize_t*)tif->tif_data = TIFFScanlineSize(tif);
50	return (1);
51}
52
53static int
54PackBitsPostEncode(TIFF* tif)
55{
56        if (tif->tif_data)
57            _TIFFfree(tif->tif_data);
58	return (1);
59}
60
61/*
62 * NB: tidata is the type representing *(tidata_t);
63 *     if tidata_t is made signed then this type must
64 *     be adjusted accordingly.
65 */
66typedef unsigned char tidata;
67
68/*
69 * Encode a run of pixels.
70 */
71static int
72PackBitsEncode(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
73{
74	unsigned char* bp = (unsigned char*) buf;
75	tidata_t op, ep, lastliteral;
76	long n, slop;
77	int b;
78	enum { BASE, LITERAL, RUN, LITERAL_RUN } state;
79
80	(void) s;
81	op = tif->tif_rawcp;
82	ep = tif->tif_rawdata + tif->tif_rawdatasize;
83	state = BASE;
84	lastliteral = 0;
85	while (cc > 0) {
86		/*
87		 * Find the longest string of identical bytes.
88		 */
89		b = *bp++, cc--, n = 1;
90		for (; cc > 0 && b == *bp; cc--, bp++)
91			n++;
92	again:
93		if (op + 2 >= ep) {		/* insure space for new data */
94			/*
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.
99			 */
100			if (state == LITERAL || state == LITERAL_RUN) {
101				slop = op - lastliteral;
102				tif->tif_rawcc += lastliteral - tif->tif_rawcp;
103				if (!TIFFFlushData1(tif))
104					return (-1);
105				op = tif->tif_rawcp;
106				while (slop-- > 0)
107					*op++ = *lastliteral++;
108				lastliteral = tif->tif_rawcp;
109			} else {
110				tif->tif_rawcc += op - tif->tif_rawcp;
111				if (!TIFFFlushData1(tif))
112					return (-1);
113				op = tif->tif_rawcp;
114			}
115		}
116		switch (state) {
117		case BASE:		/* initial state, set run/literal */
118			if (n > 1) {
119				state = RUN;
120				if (n > 128) {
121					*op++ = (tidata) -127;
122					*op++ = (tidataval_t) b;
123					n -= 128;
124					goto again;
125				}
126				*op++ = (tidataval_t)(-(n-1));
127				*op++ = (tidataval_t) b;
128			} else {
129				lastliteral = op;
130				*op++ = 0;
131				*op++ = (tidataval_t) b;
132				state = LITERAL;
133			}
134			break;
135		case LITERAL:		/* last object was literal string */
136			if (n > 1) {
137				state = LITERAL_RUN;
138				if (n > 128) {
139					*op++ = (tidata) -127;
140					*op++ = (tidataval_t) b;
141					n -= 128;
142					goto again;
143				}
144				*op++ = (tidataval_t)(-(n-1));	/* encode run */
145				*op++ = (tidataval_t) b;
146			} else {			/* extend literal */
147				if (++(*lastliteral) == 127)
148					state = BASE;
149				*op++ = (tidataval_t) b;
150			}
151			break;
152		case RUN:		/* last object was run */
153			if (n > 1) {
154				if (n > 128) {
155					*op++ = (tidata) -127;
156					*op++ = (tidataval_t) b;
157					n -= 128;
158					goto again;
159				}
160				*op++ = (tidataval_t)(-(n-1));
161				*op++ = (tidataval_t) b;
162			} else {
163				lastliteral = op;
164				*op++ = 0;
165				*op++ = (tidataval_t) b;
166				state = LITERAL;
167			}
168			break;
169		case LITERAL_RUN:	/* literal followed by a run */
170			/*
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.
175			 */
176			if (n == 1 && op[-2] == (tidata) -1 &&
177			    *lastliteral < 126) {
178				state = (((*lastliteral) += 2) == 127 ?
179				    BASE : LITERAL);
180				op[-2] = op[-1];	/* replicate */
181			} else
182				state = RUN;
183			goto again;
184		}
185	}
186	tif->tif_rawcc += op - tif->tif_rawcp;
187	tif->tif_rawcp = op;
188	return (1);
189}
190
191/*
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.
197 */
198static int
199PackBitsEncodeChunk(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
200{
201	tsize_t rowsize = *(tsize_t*)tif->tif_data;
202
203	while ((long)cc > 0) {
204		int	chunk = rowsize;
205
206		if( cc < chunk )
207		    chunk = cc;
208
209		if (PackBitsEncode(tif, bp, chunk, s) < 0)
210		    return (-1);
211		bp += chunk;
212		cc -= chunk;
213	}
214	return (1);
215}
216
217static int
218PackBitsDecode(TIFF* tif, tidata_t op, tsize_t occ, tsample_t s)
219{
220	char *bp;
221	tsize_t cc;
222	long n;
223	int b;
224
225	(void) s;
226	bp = (char*) tif->tif_rawcp;
227	cc = tif->tif_rawcc;
228	while (cc > 0 && (long)occ > 0) {
229		n = (long) *bp++, cc--;
230		/*
231		 * Watch out for compilers that
232		 * don't sign extend chars...
233		 */
234		if (n >= 128)
235			n -= 256;
236		if (n < 0) {		/* replicate next byte -n+1 times */
237			if (n == -128)	/* nop */
238				continue;
239                        n = -n + 1;
240                        if( occ < n )
241                        {
242							TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
243                                        "PackBitsDecode: discarding %ld bytes "
244                                        "to avoid buffer overrun",
245                                        n - occ);
246                            n = occ;
247                        }
248			occ -= n;
249			b = *bp++, cc--;
250			while (n-- > 0)
251				*op++ = (tidataval_t) b;
252		} else {		/* copy next n+1 bytes literally */
253			if (occ < n + 1)
254                        {
255                            TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
256                                        "PackBitsDecode: discarding %ld bytes "
257                                        "to avoid buffer overrun",
258                                        n - occ + 1);
259                            n = occ - 1;
260                        }
261                        _TIFFmemcpy(op, bp, ++n);
262			op += n; occ -= n;
263			bp += n; cc -= n;
264		}
265	}
266	tif->tif_rawcp = (tidata_t) bp;
267	tif->tif_rawcc = cc;
268	if (occ > 0) {
269		TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
270		    "PackBitsDecode: Not enough data for scanline %ld",
271		    (long) tif->tif_row);
272		return (0);
273	}
274	return (1);
275}
276
277int
278TIFFInitPackBits(TIFF* tif, int scheme)
279{
280	(void) 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;
289	return (1);
290}
291#endif /* PACKBITS_SUPPORT */
292
293/* vim: set ts=8 sts=8 sw=8 noet: */
294/*
295 * Local Variables:
296 * mode: c
297 * c-basic-offset: 8
298 * fill-column: 78
299 * End:
300 */
301