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
71 0 : ThunderSetupDecode(TIFF* tif)
72 : {
73 : static const char module[] = "ThunderSetupDecode";
74 :
75 0 : if( tif->tif_dir.td_bitspersample != 4 )
76 : {
77 0 : 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 0 : return 0;
81 : }
82 :
83 :
84 0 : return (1);
85 : }
86 :
87 : static int
88 0 : 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 0 : bp = (unsigned char *)tif->tif_rawcp;
97 0 : cc = tif->tif_rawcc;
98 0 : lastpixel = 0;
99 0 : npixels = 0;
100 0 : while (cc > 0 && npixels < maxpixels) {
101 : int n, delta;
102 :
103 0 : n = *bp++, cc--;
104 0 : 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 0 : if (npixels & 1) {
111 0 : op[0] |= lastpixel;
112 0 : lastpixel = *op++; npixels++; n--;
113 : } else
114 0 : lastpixel |= lastpixel << 4;
115 0 : npixels += n;
116 0 : if (npixels < maxpixels) {
117 0 : for (; n > 0; n -= 2)
118 0 : *op++ = (uint8) lastpixel;
119 : }
120 0 : if (n == -1)
121 0 : *--op &= 0xf0;
122 0 : lastpixel &= 0xf;
123 0 : break;
124 : case THUNDER_2BITDELTAS: /* 2-bit deltas */
125 0 : if ((delta = ((n >> 4) & 3)) != DELTA2_SKIP)
126 0 : SETPIXEL(op, lastpixel + twobitdeltas[delta]);
127 0 : if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP)
128 0 : SETPIXEL(op, lastpixel + twobitdeltas[delta]);
129 0 : if ((delta = (n & 3)) != DELTA2_SKIP)
130 0 : SETPIXEL(op, lastpixel + twobitdeltas[delta]);
131 0 : break;
132 : case THUNDER_3BITDELTAS: /* 3-bit deltas */
133 0 : if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP)
134 0 : SETPIXEL(op, lastpixel + threebitdeltas[delta]);
135 0 : if ((delta = (n & 7)) != DELTA3_SKIP)
136 0 : SETPIXEL(op, lastpixel + threebitdeltas[delta]);
137 0 : break;
138 : case THUNDER_RAW: /* raw data */
139 0 : SETPIXEL(op, n);
140 : break;
141 : }
142 : }
143 0 : tif->tif_rawcp = (uint8*) bp;
144 0 : tif->tif_rawcc = cc;
145 0 : 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 0 : 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 0 : return (0);
162 : }
163 :
164 0 : return (1);
165 : }
166 :
167 : static int
168 0 : ThunderDecodeRow(TIFF* tif, uint8* buf, tmsize_t occ, uint16 s)
169 : {
170 : static const char module[] = "ThunderDecodeRow";
171 0 : uint8* row = buf;
172 :
173 : (void) s;
174 0 : if (occ % tif->tif_scanlinesize)
175 : {
176 0 : TIFFErrorExt(tif->tif_clientdata, module, "Fractional scanlines cannot be read");
177 0 : return (0);
178 : }
179 0 : while (occ > 0) {
180 0 : if (!ThunderDecode(tif, row, tif->tif_dir.td_imagewidth))
181 0 : return (0);
182 0 : occ -= tif->tif_scanlinesize;
183 0 : row += tif->tif_scanlinesize;
184 : }
185 0 : return (1);
186 : }
187 :
188 : int
189 0 : TIFFInitThunderScan(TIFF* tif, int scheme)
190 : {
191 : (void) scheme;
192 :
193 0 : tif->tif_setupdecode = ThunderSetupDecode;
194 0 : tif->tif_decoderow = ThunderDecodeRow;
195 0 : tif->tif_decodestrip = ThunderDecodeRow;
196 0 : 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 : */
|
