1/* PDFlib GmbH cvsid: $Id: tif_packbits.c 14574 2005-10-29 16:27:43Z bonefish $ */
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 <assert.h>
35#include <stdio.h>
36
37#ifdef PDFLIB_TIFFWRITE_SUPPORT
38static int
39PackBitsPreEncode(TIFF* tif, tsample_t s)
40{
41	(void) s;
42	/*
43	 * Calculate the scanline/tile-width size in bytes.
44	 */
45	if (isTiled(tif))
46		tif->tif_data = (tidata_t) TIFFTileRowSize(tif);
47	else
48		tif->tif_data = (tidata_t) TIFFScanlineSize(tif);
49	return (1);
50}
51#endif /* PDFLIB_TIFFWRITE_SUPPORT */
52
53/*
54 * NB: tidata is the type representing *(tidata_t);
55 *     if tidata_t is made signed then this type must
56 *     be adjusted accordingly.
57 */
58typedef unsigned char tidata;
59
60/*
61 * Encode a run of pixels.
62 */
63#ifdef PDFLIB_TIFFWRITE_SUPPORT
64static int
65PackBitsEncode(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
66{
67	tif_char* bp = (tif_char*) buf;
68	tidata_t op, ep, lastliteral;
69	long n, slop;
70	int b;
71	enum { BASE, LITERAL, RUN, LITERAL_RUN } state;
72
73	(void) s;
74	op = tif->tif_rawcp;
75	ep = tif->tif_rawdata + tif->tif_rawdatasize;
76	state = BASE;
77	lastliteral = 0;
78	while (cc > 0) {
79		/*
80		 * Find the longest string of identical bytes.
81		 */
82		b = *bp++, cc--, n = 1;
83		for (; cc > 0 && b == *bp; cc--, bp++)
84			n++;
85	again:
86		if (op + 2 >= ep) {		/* insure space for new data */
87			/*
88			 * Be careful about writing the last
89			 * literal.  Must write up to that point
90			 * and then copy the remainder to the
91			 * front of the buffer.
92			 */
93			if (state == LITERAL || state == LITERAL_RUN) {
94				slop = op - lastliteral;
95				tif->tif_rawcc += lastliteral - tif->tif_rawcp;
96				if (!TIFFFlushData1(tif))
97					return (-1);
98				op = tif->tif_rawcp;
99				while (slop-- > 0)
100					*op++ = *lastliteral++;
101				lastliteral = tif->tif_rawcp;
102			} else {
103				tif->tif_rawcc += op - tif->tif_rawcp;
104				if (!TIFFFlushData1(tif))
105					return (-1);
106				op = tif->tif_rawcp;
107			}
108		}
109		switch (state) {
110		case BASE:		/* initial state, set run/literal */
111			if (n > 1) {
112				state = RUN;
113				if (n > 128) {
114					*op++ = (tidata) -127;
115					*op++ = b;
116					n -= 128;
117					goto again;
118				}
119				*op++ = (tidataval_t)(-(n-1));
120				*op++ = b;
121			} else {
122				lastliteral = op;
123				*op++ = 0;
124				*op++ = b;
125				state = LITERAL;
126			}
127			break;
128		case LITERAL:		/* last object was literal string */
129			if (n > 1) {
130				state = LITERAL_RUN;
131				if (n > 128) {
132					*op++ = (tidata) -127;
133					*op++ = b;
134					n -= 128;
135					goto again;
136				}
137				*op++ = (tidataval_t)(-(n-1));	/* encode run */
138				*op++ = b;
139			} else {			/* extend literal */
140				if (++(*lastliteral) == 127)
141					state = BASE;
142				*op++ = b;
143			}
144			break;
145		case RUN:		/* last object was run */
146			if (n > 1) {
147				if (n > 128) {
148					*op++ = (tidata) -127;
149					*op++ = b;
150					n -= 128;
151					goto again;
152				}
153				*op++ = (tidataval_t)(-(n-1));
154				*op++ = b;
155			} else {
156				lastliteral = op;
157				*op++ = 0;
158				*op++ = b;
159				state = LITERAL;
160			}
161			break;
162		case LITERAL_RUN:	/* literal followed by a run */
163			/*
164			 * Check to see if previous run should
165			 * be converted to a literal, in which
166			 * case we convert literal-run-literal
167			 * to a single literal.
168			 */
169			if (n == 1 && op[-2] == (tidata) -1 &&
170			    *lastliteral < 126) {
171				state = (((*lastliteral) += 2) == 127 ?
172				    BASE : LITERAL);
173				op[-2] = op[-1];	/* replicate */
174			} else
175				state = RUN;
176			goto again;
177		}
178	}
179	tif->tif_rawcc += op - tif->tif_rawcp;
180	tif->tif_rawcp = op;
181	return (1);
182}
183#endif /* PDFLIB_TIFFWRITE_SUPPORT */
184
185/*
186 * Encode a rectangular chunk of pixels.  We break it up
187 * into row-sized pieces to insure that encoded runs do
188 * not span rows.  Otherwise, there can be problems with
189 * the decoder if data is read, for example, by scanlines
190 * when it was encoded by strips.
191 */
192#ifdef PDFLIB_TIFFWRITE_SUPPORT
193static int
194PackBitsEncodeChunk(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
195{
196    tsize_t rowsize = (tsize_t) tif->tif_data;
197
198    assert(rowsize > 0);
199
200#ifdef YCBCR_SUPPORT
201    /*
202     * YCBCR data isn't really separable into rows, so we
203     * might as well encode the whole tile/strip as one chunk.
204     */
205    if( tif->tif_dir.td_photometric == PHOTOMETRIC_YCBCR )
206        rowsize = (tsize_t) tif->tif_data;
207#endif
208
209    while ((long)cc > 0) {
210        int	chunk = rowsize;
211
212        if( cc < chunk )
213            chunk = cc;
214
215        if (PackBitsEncode(tif, bp, chunk, s) < 0)
216            return (-1);
217        bp += chunk;
218        cc -= chunk;
219    }
220    return (1);
221}
222#endif /* PDFLIB_TIFFWRITE_SUPPORT */
223
224static int
225PackBitsDecode(TIFF* tif, tidata_t op, tsize_t occ, tsample_t s)
226{
227	char *bp;
228	tsize_t cc;
229	long n;
230	int b;
231
232	(void) s;
233	bp = (char*) tif->tif_rawcp;
234	cc = tif->tif_rawcc;
235	while (cc > 0 && (long)occ > 0) {
236		n = (long) *bp++, cc--;
237		/*
238		 * Watch out for compilers that
239		 * don't sign extend chars...
240		 */
241		if (n >= 128)
242			n -= 256;
243		if (n < 0) {		/* replicate next byte -n+1 times */
244			if (n == -128)	/* nop */
245				continue;
246                        n = -n + 1;
247                        if( occ < n )
248                        {
249                            TIFFWarning(tif->tif_name,
250                                        "PackBitsDecode: discarding %d bytes "
251                                        "to avoid buffer overrun",
252                                        n - occ);
253                            n = occ;
254                        }
255			occ -= n;
256			b = *bp++, cc--;
257			while (n-- > 0)
258				*op++ = b;
259		} else {		/* copy next n+1 bytes literally */
260			if (occ < n + 1)
261                        {
262                            TIFFWarning(tif->tif_name,
263                                        "PackBitsDecode: discarding %d bytes "
264                                        "to avoid buffer overrun",
265                                        n - occ + 1);
266                            n = occ - 1;
267                        }
268                        _TIFFmemcpy(op, bp, ++n);
269			op += n; occ -= n;
270			bp += n; cc -= n;
271		}
272	}
273	tif->tif_rawcp = (tidata_t) bp;
274	tif->tif_rawcc = cc;
275	if (occ > 0) {
276		TIFFError(tif->tif_name,
277		    "PackBitsDecode: Not enough data for scanline %ld",
278		    (long) tif->tif_row);
279		return (0);
280	}
281	return (1);
282}
283
284int
285TIFFInitPackBits(TIFF* tif, int scheme)
286{
287	(void) scheme;
288	tif->tif_decoderow = PackBitsDecode;
289	tif->tif_decodestrip = PackBitsDecode;
290	tif->tif_decodetile = PackBitsDecode;
291#ifdef PDFLIB_TIFFWRITE_SUPPORT
292	tif->tif_preencode = PackBitsPreEncode;
293	tif->tif_encoderow = PackBitsEncode;
294	tif->tif_encodestrip = PackBitsEncodeChunk;
295	tif->tif_encodetile = PackBitsEncodeChunk;
296#endif /* PDFLIB_TIFFWRITE_SUPPORT */
297	return (1);
298}
299#endif /* PACKBITS_SUPPORT */
300