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Diffstat (limited to 'src/libtiff/tif_thunder.c')
| -rw-r--r-- | src/libtiff/tif_thunder.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/src/libtiff/tif_thunder.c b/src/libtiff/tif_thunder.c new file mode 100644 index 0000000..40f0618 --- /dev/null +++ b/src/libtiff/tif_thunder.c @@ -0,0 +1,158 @@ +/* $Id: tif_thunder.c,v 1.1 2008/10/17 06:16:07 scuri Exp $ */ + +/* + * Copyright (c) 1988-1997 Sam Leffler + * Copyright (c) 1991-1997 Silicon Graphics, Inc. + * + * Permission to use, copy, modify, distribute, and sell this software and + * its documentation for any purpose is hereby granted without fee, provided + * that (i) the above copyright notices and this permission notice appear in + * all copies of the software and related documentation, and (ii) the names of + * Sam Leffler and Silicon Graphics may not be used in any advertising or + * publicity relating to the software without the specific, prior written + * permission of Sam Leffler and Silicon Graphics. + * + * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, + * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY + * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. + * + * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR + * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, + * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, + * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF + * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE + * OF THIS SOFTWARE. + */ + +#include "tiffiop.h" +#ifdef THUNDER_SUPPORT +/* + * TIFF Library. + * + * ThunderScan 4-bit Compression Algorithm Support + */ + +/* + * ThunderScan uses an encoding scheme designed for + * 4-bit pixel values. Data is encoded in bytes, with + * each byte split into a 2-bit code word and a 6-bit + * data value. The encoding gives raw data, runs of + * pixels, or pixel values encoded as a delta from the + * previous pixel value. For the latter, either 2-bit + * or 3-bit delta values are used, with the deltas packed + * into a single byte. + */ +#define THUNDER_DATA 0x3f /* mask for 6-bit data */ +#define THUNDER_CODE 0xc0 /* mask for 2-bit code word */ +/* code values */ +#define THUNDER_RUN 0x00 /* run of pixels w/ encoded count */ +#define THUNDER_2BITDELTAS 0x40 /* 3 pixels w/ encoded 2-bit deltas */ +#define DELTA2_SKIP 2 /* skip code for 2-bit deltas */ +#define THUNDER_3BITDELTAS 0x80 /* 2 pixels w/ encoded 3-bit deltas */ +#define DELTA3_SKIP 4 /* skip code for 3-bit deltas */ +#define THUNDER_RAW 0xc0 /* raw data encoded */ + +static const int twobitdeltas[4] = { 0, 1, 0, -1 }; +static const int threebitdeltas[8] = { 0, 1, 2, 3, 0, -3, -2, -1 }; + +#define SETPIXEL(op, v) { \ + lastpixel = (v) & 0xf; \ + if (npixels++ & 1) \ + *op++ |= lastpixel; \ + else \ + op[0] = (tidataval_t) (lastpixel << 4); \ +} + +static int +ThunderDecode(TIFF* tif, tidata_t op, tsize_t maxpixels) +{ + register unsigned char *bp; + register tsize_t cc; + unsigned int lastpixel; + tsize_t npixels; + + bp = (unsigned char *)tif->tif_rawcp; + cc = tif->tif_rawcc; + lastpixel = 0; + npixels = 0; + while (cc > 0 && npixels < maxpixels) { + int n, delta; + + n = *bp++, cc--; + switch (n & THUNDER_CODE) { + case THUNDER_RUN: /* pixel run */ + /* + * Replicate the last pixel n times, + * where n is the lower-order 6 bits. + */ + if (npixels & 1) { + op[0] |= lastpixel; + lastpixel = *op++; npixels++; n--; + } else + lastpixel |= lastpixel << 4; + npixels += n; + if (npixels < maxpixels) { + for (; n > 0; n -= 2) + *op++ = (tidataval_t) lastpixel; + } + if (n == -1) + *--op &= 0xf0; + lastpixel &= 0xf; + break; + case THUNDER_2BITDELTAS: /* 2-bit deltas */ + if ((delta = ((n >> 4) & 3)) != DELTA2_SKIP) + SETPIXEL(op, lastpixel + twobitdeltas[delta]); + if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP) + SETPIXEL(op, lastpixel + twobitdeltas[delta]); + if ((delta = (n & 3)) != DELTA2_SKIP) + SETPIXEL(op, lastpixel + twobitdeltas[delta]); + break; + case THUNDER_3BITDELTAS: /* 3-bit deltas */ + if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP) + SETPIXEL(op, lastpixel + threebitdeltas[delta]); + if ((delta = (n & 7)) != DELTA3_SKIP) + SETPIXEL(op, lastpixel + threebitdeltas[delta]); + break; + case THUNDER_RAW: /* raw data */ + SETPIXEL(op, n); + break; + } + } + tif->tif_rawcp = (tidata_t) bp; + tif->tif_rawcc = cc; + if (npixels != maxpixels) { + TIFFErrorExt(tif->tif_clientdata, tif->tif_name, + "ThunderDecode: %s data at scanline %ld (%lu != %lu)", + npixels < maxpixels ? "Not enough" : "Too much", + (long) tif->tif_row, (long) npixels, (long) maxpixels); + return (0); + } + return (1); +} + +static int +ThunderDecodeRow(TIFF* tif, tidata_t buf, tsize_t occ, tsample_t s) +{ + tidata_t row = buf; + + (void) s; + while ((long)occ > 0) { + if (!ThunderDecode(tif, row, tif->tif_dir.td_imagewidth)) + return (0); + occ -= tif->tif_scanlinesize; + row += tif->tif_scanlinesize; + } + return (1); +} + +int +TIFFInitThunderScan(TIFF* tif, int scheme) +{ + (void) scheme; + tif->tif_decoderow = ThunderDecodeRow; + tif->tif_decodestrip = ThunderDecodeRow; + return (1); +} +#endif /* THUNDER_SUPPORT */ + +/* vim: set ts=8 sts=8 sw=8 noet: */ |