1 /* $Id: tif_thunder.c,v 1.13 2016-09-04 21:32:56 erouault 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 <precomp.h> 28 //#include <assert.h> 29 30 #ifdef THUNDER_SUPPORT 31 /* 32 * TIFF Library. 33 * 34 * ThunderScan 4-bit Compression Algorithm Support 35 */ 36 37 /* 38 * ThunderScan uses an encoding scheme designed for 39 * 4-bit pixel values. Data is encoded in bytes, with 40 * each byte split into a 2-bit code word and a 6-bit 41 * data value. The encoding gives raw data, runs of 42 * pixels, or pixel values encoded as a delta from the 43 * previous pixel value. For the latter, either 2-bit 44 * or 3-bit delta values are used, with the deltas packed 45 * into a single byte. 46 */ 47 #define THUNDER_DATA 0x3f /* mask for 6-bit data */ 48 #define THUNDER_CODE 0xc0 /* mask for 2-bit code word */ 49 /* code values */ 50 #define THUNDER_RUN 0x00 /* run of pixels w/ encoded count */ 51 #define THUNDER_2BITDELTAS 0x40 /* 3 pixels w/ encoded 2-bit deltas */ 52 #define DELTA2_SKIP 2 /* skip code for 2-bit deltas */ 53 #define THUNDER_3BITDELTAS 0x80 /* 2 pixels w/ encoded 3-bit deltas */ 54 #define DELTA3_SKIP 4 /* skip code for 3-bit deltas */ 55 #define THUNDER_RAW 0xc0 /* raw data encoded */ 56 57 static const int twobitdeltas[4] = { 0, 1, 0, -1 }; 58 static const int threebitdeltas[8] = { 0, 1, 2, 3, 0, -3, -2, -1 }; 59 60 #define SETPIXEL(op, v) { \ 61 lastpixel = (v) & 0xf; \ 62 if ( npixels < maxpixels ) \ 63 { \ 64 if (npixels++ & 1) \ 65 *op++ |= lastpixel; \ 66 else \ 67 op[0] = (uint8) (lastpixel << 4); \ 68 } \ 69 } 70 71 static int 72 ThunderSetupDecode(TIFF* tif) 73 { 74 static const char module[] = "ThunderSetupDecode"; 75 76 if( tif->tif_dir.td_bitspersample != 4 ) 77 { 78 TIFFErrorExt(tif->tif_clientdata, module, 79 "Wrong bitspersample value (%d), Thunder decoder only supports 4bits per sample.", 80 (int) tif->tif_dir.td_bitspersample ); 81 return 0; 82 } 83 84 85 return (1); 86 } 87 88 static int 89 ThunderDecode(TIFF* tif, uint8* op, tmsize_t maxpixels) 90 { 91 static const char module[] = "ThunderDecode"; 92 register unsigned char *bp; 93 register tmsize_t cc; 94 unsigned int lastpixel; 95 tmsize_t npixels; 96 97 bp = (unsigned char *)tif->tif_rawcp; 98 cc = tif->tif_rawcc; 99 lastpixel = 0; 100 npixels = 0; 101 while (cc > 0 && npixels < maxpixels) { 102 int n, delta; 103 104 n = *bp++; 105 cc--; 106 switch (n & THUNDER_CODE) { 107 case THUNDER_RUN: /* pixel run */ 108 /* 109 * Replicate the last pixel n times, 110 * where n is the lower-order 6 bits. 111 */ 112 if (npixels & 1) { 113 op[0] |= lastpixel; 114 lastpixel = *op++; npixels++; n--; 115 } else 116 lastpixel |= lastpixel << 4; 117 npixels += n; 118 if (npixels < maxpixels) { 119 for (; n > 0; n -= 2) 120 *op++ = (uint8) lastpixel; 121 } 122 if (n == -1) 123 *--op &= 0xf0; 124 lastpixel &= 0xf; 125 break; 126 case THUNDER_2BITDELTAS: /* 2-bit deltas */ 127 if ((delta = ((n >> 4) & 3)) != DELTA2_SKIP) 128 SETPIXEL(op, lastpixel + twobitdeltas[delta]); 129 if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP) 130 SETPIXEL(op, lastpixel + twobitdeltas[delta]); 131 if ((delta = (n & 3)) != DELTA2_SKIP) 132 SETPIXEL(op, lastpixel + twobitdeltas[delta]); 133 break; 134 case THUNDER_3BITDELTAS: /* 3-bit deltas */ 135 if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP) 136 SETPIXEL(op, lastpixel + threebitdeltas[delta]); 137 if ((delta = (n & 7)) != DELTA3_SKIP) 138 SETPIXEL(op, lastpixel + threebitdeltas[delta]); 139 break; 140 case THUNDER_RAW: /* raw data */ 141 SETPIXEL(op, n); 142 break; 143 } 144 } 145 tif->tif_rawcp = (uint8*) bp; 146 tif->tif_rawcc = cc; 147 if (npixels != maxpixels) { 148 #if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__)) 149 TIFFErrorExt(tif->tif_clientdata, module, 150 "%s data at scanline %lu (%I64u != %I64u)", 151 npixels < maxpixels ? "Not enough" : "Too much", 152 (unsigned long) tif->tif_row, 153 (unsigned __int64) npixels, 154 (unsigned __int64) maxpixels); 155 #else 156 TIFFErrorExt(tif->tif_clientdata, module, 157 "%s data at scanline %lu (%llu != %llu)", 158 npixels < maxpixels ? "Not enough" : "Too much", 159 (unsigned long) tif->tif_row, 160 (unsigned long long) npixels, 161 (unsigned long long) maxpixels); 162 #endif 163 return (0); 164 } 165 166 return (1); 167 } 168 169 static int 170 ThunderDecodeRow(TIFF* tif, uint8* buf, tmsize_t occ, uint16 s) 171 { 172 static const char module[] = "ThunderDecodeRow"; 173 uint8* row = buf; 174 175 (void) s; 176 if (occ % tif->tif_scanlinesize) 177 { 178 TIFFErrorExt(tif->tif_clientdata, module, "Fractional scanlines cannot be read"); 179 return (0); 180 } 181 while (occ > 0) { 182 if (!ThunderDecode(tif, row, tif->tif_dir.td_imagewidth)) 183 return (0); 184 occ -= tif->tif_scanlinesize; 185 row += tif->tif_scanlinesize; 186 } 187 return (1); 188 } 189 190 int 191 TIFFInitThunderScan(TIFF* tif, int scheme) 192 { 193 (void) scheme; 194 195 tif->tif_setupdecode = ThunderSetupDecode; 196 tif->tif_decoderow = ThunderDecodeRow; 197 tif->tif_decodestrip = ThunderDecodeRow; 198 return (1); 199 } 200 #endif /* THUNDER_SUPPORT */ 201 202 /* vim: set ts=8 sts=8 sw=8 noet: */ 203 /* 204 * Local Variables: 205 * mode: c 206 * c-basic-offset: 8 207 * fill-column: 78 208 * End: 209 */ 210