src/tiff/tif_packbits.c

   1 /* $Header$ */
   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 #ifdef PACKBITS_SUPPORT
  29 /*
  30  * TIFF Library.
  31  *
  32  * PackBits Compression Algorithm Support
  33  */
  34 #include <assert.h>
  35 #include <stdio.h>
  36
  37 static int
  38 PackBitsPreEncode(TIFF* tif, tsample_t s)
  39 {
  40         (void) s;
  41         /*
  42          * Calculate the scanline/tile-width size in bytes.
  43          */
  44         if (isTiled(tif))
  45                 tif->tif_data = (tidata_t) TIFFTileRowSize(tif);
  46         else
  47                 tif->tif_data = (tidata_t) TIFFScanlineSize(tif);
  48         return (1);
  49 }
  50
  51 /*
  52  * NB: tidata is the type representing *(tidata_t);
  53  *     if tidata_t is made signed then this type must
  54  *     be adjusted accordingly.
  55  */
  56 typedef unsigned char tidata;
  57
  58 /*
  59  * Encode a run of pixels.
  60  */
  61 static int LINKAGEMODE
  62 PackBitsEncode(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
  63 {
  64         u_char* bp = (u_char*) buf;
  65         tidata_t op, ep, lastliteral;
  66         long n, slop;
  67         int b;
  68         enum { BASE, LITERAL, RUN, LITERAL_RUN } state;
  69
  70         (void) s;
  71         op = tif->tif_rawcp;
  72         ep = tif->tif_rawdata + tif->tif_rawdatasize;
  73         state = BASE;
  74         lastliteral = 0;
  75         while (cc > 0) {
  76                 /*
  77                  * Find the longest string of identical bytes.
  78                  */
  79                 b = *bp++, cc--, n = 1;
  80                 for (; cc > 0 && b == *bp; cc--, bp++)
  81                         n++;
  82         again:
  83                 if (op + 2 >= ep) {             /* insure space for new data */
  84                         /*
  85                          * Be careful about writing the last
  86                          * literal.  Must write up to that point
  87                          * and then copy the remainder to the
  88                          * front of the buffer.
  89                          */
  90                         if (state == LITERAL || state == LITERAL_RUN) {
  91                                 slop = op - lastliteral;
  92                                 tif->tif_rawcc += lastliteral - tif->tif_rawcp;
  93                                 if (!TIFFFlushData1(tif))
  94                                         return (-1);
  95                                 op = tif->tif_rawcp;
  96                                 while (slop-- > 0)
  97                                         *op++ = *lastliteral++;
  98                                 lastliteral = tif->tif_rawcp;
  99                         } else {
 100                                 tif->tif_rawcc += op - tif->tif_rawcp;
 101                                 if (!TIFFFlushData1(tif))
 102                                         return (-1);
 103                                 op = tif->tif_rawcp;
 104                         }
 105                 }
 106                 switch (state) {
 107                 case BASE:              /* initial state, set run/literal */
 108                         if (n > 1) {
 109                                 state = RUN;
 110                                 if (n > 128) {
 111                                         *op++ = (tidata) -127;
 112                                         *op++ = b;
 113                                         n -= 128;
 114                                         goto again;
 115                                 }
 116                                 *op++ = (tidataval_t)(-(n-1));
 117                                 *op++ = b;
 118                         } else {
 119                                 lastliteral = op;
 120                                 *op++ = 0;
 121                                 *op++ = b;
 122                                 state = LITERAL;
 123                         }
 124                         break;
 125                 case LITERAL:           /* last object was literal string */
 126                         if (n > 1) {
 127                                 state = LITERAL_RUN;
 128                                 if (n > 128) {
 129                                         *op++ = (tidata) -127;
 130                                         *op++ = b;
 131                                         n -= 128;
 132                                         goto again;
 133                                 }
 134                                 *op++ = (tidataval_t)(-(n-1));  /* encode run */
 135                                 *op++ = b;
 136                         } else {                        /* extend literal */
 137                                 if (++(*lastliteral) == 127)
 138                                         state = BASE;
 139                                 *op++ = b;
 140                         }
 141                         break;
 142                 case RUN:               /* last object was run */
 143                         if (n > 1) {
 144                                 if (n > 128) {
 145                                         *op++ = (tidata) -127;
 146                                         *op++ = b;
 147                                         n -= 128;
 148                                         goto again;
 149                                 }
 150                                 *op++ = (tidataval_t)(-(n-1));
 151                                 *op++ = b;
 152                         } else {
 153                                 lastliteral = op;
 154                                 *op++ = 0;
 155                                 *op++ = b;
 156                                 state = LITERAL;
 157                         }
 158                         break;
 159                 case LITERAL_RUN:       /* literal followed by a run */
 160                         /*
 161                          * Check to see if previous run should
 162                          * be converted to a literal, in which
 163                          * case we convert literal-run-literal
 164                          * to a single literal.
 165                          */
 166                         if (n == 1 && op[-2] == (tidata) -1 &&
 167                             *lastliteral < 126) {
 168                                 state = (((*lastliteral) += 2) == 127 ?
 169                                     BASE : LITERAL);
 170                                 op[-2] = op[-1];        /* replicate */
 171                         } else
 172                                 state = RUN;
 173                         goto again;
 174                 }
 175         }
 176         tif->tif_rawcc += op - tif->tif_rawcp;
 177         tif->tif_rawcp = op;
 178         return (1);
 179 }
 180
 181 /*
 182  * Encode a rectangular chunk of pixels.  We break it up
 183  * into row-sized pieces to insure that encoded runs do
 184  * not span rows.  Otherwise, there can be problems with
 185  * the decoder if data is read, for example, by scanlines
 186  * when it was encoded by strips.
 187  */
 188 static int LINKAGEMODE
 189 PackBitsEncodeChunk(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
 190 {
 191         tsize_t rowsize = (tsize_t) tif->tif_data;
 192
 193         assert(rowsize > 0);
 194         while ((long)cc > 0) {
 195                 if (PackBitsEncode(tif, bp, rowsize, s) < 0)
 196                         return (-1);
 197                 bp += rowsize;
 198                 cc -= rowsize;
 199         }
 200         return (1);
 201 }
 202
 203 static int LINKAGEMODE
 204 PackBitsDecode(TIFF* tif, tidata_t op, tsize_t occ, tsample_t s)
 205 {
 206         char *bp;
 207         tsize_t cc;
 208         long n;
 209         int b;
 210
 211         (void) s;
 212         bp = (char*) tif->tif_rawcp;
 213         cc = tif->tif_rawcc;
 214         while (cc > 0 && (long)occ > 0) {
 215                 n = (long) *bp++, cc--;
 216                 /*
 217                  * Watch out for compilers that
 218                  * don't sign extend chars...
 219                  */
 220                 if (n >= 128)
 221                         n -= 256;
 222                 if (n < 0) {            /* replicate next byte -n+1 times */
 223                         if (n == -128)  /* nop */
 224                                 continue;
 225                         n = -n + 1;
 226                         occ -= n;
 227                         b = *bp++, cc--;
 228                         while (n-- > 0)
 229                                 *op++ = b;
 230                 } else {                /* copy next n+1 bytes literally */
 231                         _TIFFmemcpy(op, bp, ++n);
 232                         op += n; occ -= n;
 233                         bp += n; cc -= n;
 234                 }
 235         }
 236         tif->tif_rawcp = (tidata_t) bp;
 237         tif->tif_rawcc = cc;
 238         if (occ > 0) {
 239                 TIFFError(tif->tif_name,
 240                     "PackBitsDecode: Not enough data for scanline %ld",
 241                     (long) tif->tif_row);
 242                 return (0);
 243         }
 244         /* check for buffer overruns? */
 245         return (1);
 246 }
 247
 248 int
 249 TIFFInitPackBits(TIFF* tif, int scheme)
 250 {
 251         (void) scheme;
 252         tif->tif_decoderow = PackBitsDecode;
 253         tif->tif_decodestrip = PackBitsDecode;
 254         tif->tif_decodetile = PackBitsDecode;
 255         tif->tif_preencode = PackBitsPreEncode;
 256         tif->tif_encoderow = PackBitsEncode;
 257         tif->tif_encodestrip = PackBitsEncodeChunk;
 258         tif->tif_encodetile = PackBitsEncodeChunk;
 259         return (1);
 260 }
 261 #endif /* PACKBITS_SUPPORT */