1 /* $Id: tif_thunder.c,v 1.12 2011-04-02 20:54:09 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 #include <assert.h>
29 #ifdef THUNDER_SUPPORT
30 /*
31 * TIFF Library.
32 *
33 * ThunderScan 4-bit Compression Algorithm Support
34 */
35
36 /*
37 * ThunderScan uses an encoding scheme designed for
38 * 4-bit pixel values. Data is encoded in bytes, with
39 * each byte split into a 2-bit code word and a 6-bit
40 * data value. The encoding gives raw data, runs of
41 * pixels, or pixel values encoded as a delta from the
42 * previous pixel value. For the latter, either 2-bit
43 * or 3-bit delta values are used, with the deltas packed
44 * into a single byte.
45 */
46 #define THUNDER_DATA 0x3f /* mask for 6-bit data */
47 #define THUNDER_CODE 0xc0 /* mask for 2-bit code word */
48 /* code values */
49 #define THUNDER_RUN 0x00 /* run of pixels w/ encoded count */
50 #define THUNDER_2BITDELTAS 0x40 /* 3 pixels w/ encoded 2-bit deltas */
51 #define DELTA2_SKIP 2 /* skip code for 2-bit deltas */
52 #define THUNDER_3BITDELTAS 0x80 /* 2 pixels w/ encoded 3-bit deltas */
53 #define DELTA3_SKIP 4 /* skip code for 3-bit deltas */
54 #define THUNDER_RAW 0xc0 /* raw data encoded */
55
56 static const int twobitdeltas[4] = { 0, 1, 0, -1 };
57 static const int threebitdeltas[8] = { 0, 1, 2, 3, 0, -3, -2, -1 };
58
59 #define SETPIXEL(op, v) { \
60 lastpixel = (v) & 0xf; \
61 if ( npixels < maxpixels ) \
62 { \
63 if (npixels++ & 1) \
64 *op++ |= lastpixel; \
65 else \
66 op[0] = (uint8) (lastpixel << 4); \
67 } \
68 }
69
70 static int
ThunderSetupDecode(TIFF * tif)71 ThunderSetupDecode(TIFF* tif)
72 {
73 static const char module[] = "ThunderSetupDecode";
74
75 if( tif->tif_dir.td_bitspersample != 4 )
76 {
77 TIFFErrorExt(tif->tif_clientdata, module,
78 "Wrong bitspersample value (%d), Thunder decoder only supports 4bits per sample.",
79 (int) tif->tif_dir.td_bitspersample );
80 return 0;
81 }
82
83
84 return (1);
85 }
86
87 static int
ThunderDecode(TIFF * tif,uint8 * op,tmsize_t maxpixels)88 ThunderDecode(TIFF* tif, uint8* op, tmsize_t maxpixels)
89 {
90 static const char module[] = "ThunderDecode";
91 register unsigned char *bp;
92 register tmsize_t cc;
93 unsigned int lastpixel;
94 tmsize_t npixels;
95
96 bp = (unsigned char *)tif->tif_rawcp;
97 cc = tif->tif_rawcc;
98 lastpixel = 0;
99 npixels = 0;
100 while (cc > 0 && npixels < maxpixels) {
101 int n, delta;
102
103 n = *bp++, 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, lastpixel + twobitdeltas[delta]);
127 if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP)
128 SETPIXEL(op, lastpixel + twobitdeltas[delta]);
129 if ((delta = (n & 3)) != DELTA2_SKIP)
130 SETPIXEL(op, lastpixel + twobitdeltas[delta]);
131 break;
132 case THUNDER_3BITDELTAS: /* 3-bit deltas */
133 if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP)
134 SETPIXEL(op, lastpixel + threebitdeltas[delta]);
135 if ((delta = (n & 7)) != DELTA3_SKIP)
136 SETPIXEL(op, 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