src/tiff/libtiff/tif_thunder.c

   1 /* $Id$ */
   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  */