| /* |
| * 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" |
| #include <assert.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 < maxpixels) \ |
| { \ |
| if (npixels++ & 1) \ |
| *op++ |= lastpixel; \ |
| else \ |
| op[0] = (uint8_t)(lastpixel << 4); \ |
| } \ |
| } |
| |
| static int ThunderSetupDecode(TIFF *tif) |
| { |
| static const char module[] = "ThunderSetupDecode"; |
| |
| if (tif->tif_dir.td_bitspersample != 4) |
| { |
| TIFFErrorExtR(tif, module, |
| "Wrong bitspersample value (%d), Thunder decoder only " |
| "supports 4bits per sample.", |
| (int)tif->tif_dir.td_bitspersample); |
| return 0; |
| } |
| |
| return (1); |
| } |
| |
| static int ThunderDecode(TIFF *tif, uint8_t *op, tmsize_t maxpixels) |
| { |
| static const char module[] = "ThunderDecode"; |
| register unsigned char *bp; |
| register tmsize_t cc; |
| unsigned int lastpixel; |
| tmsize_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++ = (uint8_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, |
| (unsigned)((int)lastpixel + twobitdeltas[delta])); |
| if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP) |
| SETPIXEL(op, |
| (unsigned)((int)lastpixel + twobitdeltas[delta])); |
| if ((delta = (n & 3)) != DELTA2_SKIP) |
| SETPIXEL(op, |
| (unsigned)((int)lastpixel + twobitdeltas[delta])); |
| break; |
| case THUNDER_3BITDELTAS: /* 3-bit deltas */ |
| if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP) |
| SETPIXEL( |
| op, (unsigned)((int)lastpixel + threebitdeltas[delta])); |
| if ((delta = (n & 7)) != DELTA3_SKIP) |
| SETPIXEL( |
| op, (unsigned)((int)lastpixel + threebitdeltas[delta])); |
| break; |
| case THUNDER_RAW: /* raw data */ |
| SETPIXEL(op, n); |
| break; |
| } |
| } |
| tif->tif_rawcp = (uint8_t *)bp; |
| tif->tif_rawcc = cc; |
| if (npixels != maxpixels) |
| { |
| TIFFErrorExtR(tif, module, |
| "%s data at scanline %lu (%" PRIu64 " != %" PRIu64 ")", |
| npixels < maxpixels ? "Not enough" : "Too much", |
| (unsigned long)tif->tif_row, (uint64_t)npixels, |
| (uint64_t)maxpixels); |
| return (0); |
| } |
| |
| return (1); |
| } |
| |
| static int ThunderDecodeRow(TIFF *tif, uint8_t *buf, tmsize_t occ, uint16_t s) |
| { |
| static const char module[] = "ThunderDecodeRow"; |
| uint8_t *row = buf; |
| |
| (void)s; |
| if (occ % tif->tif_scanlinesize) |
| { |
| TIFFErrorExtR(tif, module, "Fractional scanlines cannot be read"); |
| return (0); |
| } |
| while (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_setupdecode = ThunderSetupDecode; |
| tif->tif_decoderow = ThunderDecodeRow; |
| tif->tif_decodestrip = ThunderDecodeRow; |
| return (1); |
| } |
| #endif /* THUNDER_SUPPORT */ |
