1 /*
2 * Copyright (c) 1988-1997 Sam Leffler
3 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
4 *
5 * Permission to use, copy, modify, distribute, and sell this software and
6 * its documentation for any purpose is hereby granted without fee, provided
7 * that (i) the above copyright notices and this permission notice appear in
8 * all copies of the software and related documentation, and (ii) the names of
9 * Sam Leffler and Silicon Graphics may not be used in any advertising or
10 * publicity relating to the software without the specific, prior written
11 * permission of Sam Leffler and Silicon Graphics.
12 *
13 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
14 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
15 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
16 *
17 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
18 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
19 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
20 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
21 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
22 * OF THIS SOFTWARE.
23 */
24
25 #include "tiffiop.h"
26 #include <assert.h>
27 #ifdef THUNDER_SUPPORT
28 /*
29 * TIFF Library.
30 *
31 * ThunderScan 4-bit Compression Algorithm Support
32 */
33
34 /*
35 * ThunderScan uses an encoding scheme designed for
36 * 4-bit pixel values. Data is encoded in bytes, with
37 * each byte split into a 2-bit code word and a 6-bit
38 * data value. The encoding gives raw data, runs of
39 * pixels, or pixel values encoded as a delta from the
40 * previous pixel value. For the latter, either 2-bit
41 * or 3-bit delta values are used, with the deltas packed
42 * into a single byte.
43 */
44 #define THUNDER_DATA 0x3f /* mask for 6-bit data */
45 #define THUNDER_CODE 0xc0 /* mask for 2-bit code word */
46 /* code values */
47 #define THUNDER_RUN 0x00 /* run of pixels w/ encoded count */
48 #define THUNDER_2BITDELTAS 0x40 /* 3 pixels w/ encoded 2-bit deltas */
49 #define DELTA2_SKIP 2 /* skip code for 2-bit deltas */
50 #define THUNDER_3BITDELTAS 0x80 /* 2 pixels w/ encoded 3-bit deltas */
51 #define DELTA3_SKIP 4 /* skip code for 3-bit deltas */
52 #define THUNDER_RAW 0xc0 /* raw data encoded */
53
54 static const int twobitdeltas[4] = {0, 1, 0, -1};
55 static const int threebitdeltas[8] = {0, 1, 2, 3, 0, -3, -2, -1};
56
57 #define SETPIXEL(op, v) \
58 { \
59 lastpixel = (v)&0xf; \
60 if (npixels < maxpixels) \
61 { \
62 if (npixels++ & 1) \
63 *op++ |= lastpixel; \
64 else \
65 op[0] = (uint8_t)(lastpixel << 4); \
66 } \
67 }
68
ThunderSetupDecode(TIFF * tif)69 static int ThunderSetupDecode(TIFF *tif)
70 {
71 static const char module[] = "ThunderSetupDecode";
72
73 if (tif->tif_dir.td_bitspersample != 4)
74 {
75 TIFFErrorExtR(tif, module,
76 "Wrong bitspersample value (%d), Thunder decoder only "
77 "supports 4bits per sample.",
78 (int)tif->tif_dir.td_bitspersample);
79 return 0;
80 }
81
82 return (1);
83 }
84
ThunderDecode(TIFF * tif,uint8_t * op,tmsize_t maxpixels)85 static int ThunderDecode(TIFF *tif, uint8_t *op, tmsize_t maxpixels)
86 {
87 static const char module[] = "ThunderDecode";
88 register unsigned char *bp;
89 register tmsize_t cc;
90 unsigned int lastpixel;
91 tmsize_t npixels;
92
93 bp = (unsigned char *)tif->tif_rawcp;
94 cc = tif->tif_rawcc;
95 lastpixel = 0;
96 npixels = 0;
97 while (cc > 0 && npixels < maxpixels)
98 {
99 int n, delta;
100
101 n = *bp++;
102 cc--;
103 switch (n & THUNDER_CODE)
104 {
105 case THUNDER_RUN: /* pixel run */
106 /*
107 * Replicate the last pixel n times,
108 * where n is the lower-order 6 bits.
109 */
110 if (npixels & 1)
111 {
112 op[0] |= lastpixel;
113 lastpixel = *op++;
114 npixels++;
115 n--;
116 }
117 else
118 lastpixel |= lastpixel << 4;
119 npixels += n;
120 if (npixels < maxpixels)
121 {
122 for (; n > 0; n -= 2)
123 *op++ = (uint8_t)lastpixel;
124 }
125 if (n == -1)
126 *--op &= 0xf0;
127 lastpixel &= 0xf;
128 break;
129 case THUNDER_2BITDELTAS: /* 2-bit deltas */
130 if ((delta = ((n >> 4) & 3)) != DELTA2_SKIP)
131 SETPIXEL(op,
132 (unsigned)((int)lastpixel + twobitdeltas[delta]));
133 if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP)
134 SETPIXEL(op,
135 (unsigned)((int)lastpixel + twobitdeltas[delta]));
136 if ((delta = (n & 3)) != DELTA2_SKIP)
137 SETPIXEL(op,
138 (unsigned)((int)lastpixel + twobitdeltas[delta]));
139 break;
140 case THUNDER_3BITDELTAS: /* 3-bit deltas */
141 if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP)
142 SETPIXEL(
143 op, (unsigned)((int)lastpixel + threebitdeltas[delta]));
144 if ((delta = (n & 7)) != DELTA3_SKIP)
145 SETPIXEL(
146 op, (unsigned)((int)lastpixel + threebitdeltas[delta]));
147 break;
148 case THUNDER_RAW: /* raw data */
149 SETPIXEL(op, n);
150 break;
151 }
152 }
153 tif->tif_rawcp = (uint8_t *)bp;
154 tif->tif_rawcc = cc;
155 if (npixels != maxpixels)
156 {
157 TIFFErrorExtR(tif, module,
158 "%s data at scanline %lu (%" PRIu64 " != %" PRIu64 ")",
159 npixels < maxpixels ? "Not enough" : "Too much",
160 (unsigned long)tif->tif_row, (uint64_t)npixels,
161 (uint64_t)maxpixels);
162 return (0);
163 }
164
165 return (1);
166 }
167
ThunderDecodeRow(TIFF * tif,uint8_t * buf,tmsize_t occ,uint16_t s)168 static int ThunderDecodeRow(TIFF *tif, uint8_t *buf, tmsize_t occ, uint16_t s)
169 {
170 static const char module[] = "ThunderDecodeRow";
171 uint8_t *row = buf;
172
173 (void)s;
174 if (occ % tif->tif_scanlinesize)
175 {
176 TIFFErrorExtR(tif, module, "Fractional scanlines cannot be read");
177 return (0);
178 }
179 while (occ > 0)
180 {
181 if (!ThunderDecode(tif, row, tif->tif_dir.td_imagewidth))
182 return (0);
183 occ -= tif->tif_scanlinesize;
184 row += tif->tif_scanlinesize;
185 }
186 return (1);
187 }
188
TIFFInitThunderScan(TIFF * tif,int scheme)189 int TIFFInitThunderScan(TIFF *tif, int scheme)
190 {
191 (void)scheme;
192
193 tif->tif_setupdecode = ThunderSetupDecode;
194 tif->tif_decoderow = ThunderDecodeRow;
195 tif->tif_decodestrip = ThunderDecodeRow;
196 return (1);
197 }
198 #endif /* THUNDER_SUPPORT */
199