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 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 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 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 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
