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 <precomp.h>
26 //#include <assert.h>
27
28 #ifdef THUNDER_SUPPORT
29 /*
30 * TIFF Library.
31 *
32 * ThunderScan 4-bit Compression Algorithm Support
33 */
34
35 /*
36 * ThunderScan uses an encoding scheme designed for
37 * 4-bit pixel values. Data is encoded in bytes, with
38 * each byte split into a 2-bit code word and a 6-bit
39 * data value. The encoding gives raw data, runs of
40 * pixels, or pixel values encoded as a delta from the
41 * previous pixel value. For the latter, either 2-bit
42 * or 3-bit delta values are used, with the deltas packed
43 * into a single byte.
44 */
45 #define THUNDER_DATA 0x3f /* mask for 6-bit data */
46 #define THUNDER_CODE 0xc0 /* mask for 2-bit code word */
47 /* code values */
48 #define THUNDER_RUN 0x00 /* run of pixels w/ encoded count */
49 #define THUNDER_2BITDELTAS 0x40 /* 3 pixels w/ encoded 2-bit deltas */
50 #define DELTA2_SKIP 2 /* skip code for 2-bit deltas */
51 #define THUNDER_3BITDELTAS 0x80 /* 2 pixels w/ encoded 3-bit deltas */
52 #define DELTA3_SKIP 4 /* skip code for 3-bit deltas */
53 #define THUNDER_RAW 0xc0 /* raw data encoded */
54
55 static const int twobitdeltas[4] = { 0, 1, 0, -1 };
56 static const int threebitdeltas[8] = { 0, 1, 2, 3, 0, -3, -2, -1 };
57
58 #define SETPIXEL(op, v) { \
59 lastpixel = (v) & 0xf; \
60 if ( npixels < maxpixels ) \
61 { \
62 if (npixels++ & 1) \
63 *op++ |= lastpixel; \
64 else \
65 op[0] = (uint8) (lastpixel << 4); \
66 } \
67 }
68
69 static int
ThunderSetupDecode(TIFF * tif)70 ThunderSetupDecode(TIFF* tif)
71 {
72 static const char module[] = "ThunderSetupDecode";
73
74 if( tif->tif_dir.td_bitspersample != 4 )
75 {
76 TIFFErrorExt(tif->tif_clientdata, module,
77 "Wrong bitspersample value (%d), Thunder decoder only supports 4bits per sample.",
78 (int) tif->tif_dir.td_bitspersample );
79 return 0;
80 }
81
82
83 return (1);
84 }
85
86 static int
ThunderDecode(TIFF * tif,uint8 * op,tmsize_t maxpixels)87 ThunderDecode(TIFF* tif, uint8* op, tmsize_t maxpixels)
88 {
89 static const char module[] = "ThunderDecode";
90 register unsigned char *bp;
91 register tmsize_t cc;
92 unsigned int lastpixel;
93 tmsize_t npixels;
94
95 bp = (unsigned char *)tif->tif_rawcp;
96 cc = tif->tif_rawcc;
97 lastpixel = 0;
98 npixels = 0;
99 while (cc > 0 && npixels < maxpixels) {
100 int n, delta;
101
102 n = *bp++;
103 cc--;
104 switch (n & THUNDER_CODE) {
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 op[0] |= lastpixel;
112 lastpixel = *op++; npixels++; n--;
113 } else
114 lastpixel |= lastpixel << 4;
115 npixels += n;
116 if (npixels < maxpixels) {
117 for (; n > 0; n -= 2)
118 *op++ = (uint8) lastpixel;
119 }
120 if (n == -1)
121 *--op &= 0xf0;
122 lastpixel &= 0xf;
123 break;
124 case THUNDER_2BITDELTAS: /* 2-bit deltas */
125 if ((delta = ((n >> 4) & 3)) != DELTA2_SKIP)
126 SETPIXEL(op, (unsigned)((int)lastpixel + twobitdeltas[delta]));
127 if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP)
128 SETPIXEL(op, (unsigned)((int)lastpixel + twobitdeltas[delta]));
129 if ((delta = (n & 3)) != DELTA2_SKIP)
130 SETPIXEL(op, (unsigned)((int)lastpixel + twobitdeltas[delta]));
131 break;
132 case THUNDER_3BITDELTAS: /* 3-bit deltas */
133 if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP)
134 SETPIXEL(op, (unsigned)((int)lastpixel + threebitdeltas[delta]));
135 if ((delta = (n & 7)) != DELTA3_SKIP)
136 SETPIXEL(op, (unsigned)((int)lastpixel + threebitdeltas[delta]));
137 break;
138 case THUNDER_RAW: /* raw data */
139 SETPIXEL(op, n);
140 break;
141 }
142 }
143 tif->tif_rawcp = (uint8*) bp;
144 tif->tif_rawcc = cc;
145 if (npixels != maxpixels) {
146 #if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
147 TIFFErrorExt(tif->tif_clientdata, module,
148 "%s data at scanline %lu (%I64u != %I64u)",
149 npixels < maxpixels ? "Not enough" : "Too much",
150 (unsigned long) tif->tif_row,
151 (unsigned __int64) npixels,
152 (unsigned __int64) maxpixels);
153 #else
154 TIFFErrorExt(tif->tif_clientdata, module,
155 "%s data at scanline %lu (%llu != %llu)",
156 npixels < maxpixels ? "Not enough" : "Too much",
157 (unsigned long) tif->tif_row,
158 (unsigned long long) npixels,
159 (unsigned long long) maxpixels);
160 #endif
161 return (0);
162 }
163
164 return (1);
165 }
166
167 static int
ThunderDecodeRow(TIFF * tif,uint8 * buf,tmsize_t occ,uint16 s)168 ThunderDecodeRow(TIFF* tif, uint8* buf, tmsize_t occ, uint16 s)
169 {
170 static const char module[] = "ThunderDecodeRow";
171 uint8* row = buf;
172
173 (void) s;
174 if (occ % tif->tif_scanlinesize)
175 {
176 TIFFErrorExt(tif->tif_clientdata, module, "Fractional scanlines cannot be read");
177 return (0);
178 }
179 while (occ > 0) {
180 if (!ThunderDecode(tif, row, tif->tif_dir.td_imagewidth))
181 return (0);
182 occ -= tif->tif_scanlinesize;
183 row += tif->tif_scanlinesize;
184 }
185 return (1);
186 }
187
188 int
TIFFInitThunderScan(TIFF * tif,int scheme)189 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
200 /* vim: set ts=8 sts=8 sw=8 noet: */
201 /*
202 * Local Variables:
203 * mode: c
204 * c-basic-offset: 8
205 * fill-column: 78
206 * End:
207 */
208