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Open Source Computer Vision Library
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206 lines
6.3 KiB
206 lines
6.3 KiB
/* |
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* Copyright (c) 1988-1997 Sam Leffler |
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* Copyright (c) 1991-1997 Silicon Graphics, Inc. |
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* |
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* Permission to use, copy, modify, distribute, and sell this software and |
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* its documentation for any purpose is hereby granted without fee, provided |
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* that (i) the above copyright notices and this permission notice appear in |
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* all copies of the software and related documentation, and (ii) the names of |
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* Sam Leffler and Silicon Graphics may not be used in any advertising or |
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* publicity relating to the software without the specific, prior written |
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* permission of Sam Leffler and Silicon Graphics. |
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* |
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* THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, |
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* EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY |
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* WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. |
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* |
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* IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR |
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* ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, |
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* OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, |
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* WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF |
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* LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE |
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* OF THIS SOFTWARE. |
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*/ |
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#include "tiffiop.h" |
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#include <assert.h> |
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#ifdef THUNDER_SUPPORT |
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/* |
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* TIFF Library. |
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* |
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* ThunderScan 4-bit Compression Algorithm Support |
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*/ |
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/* |
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* ThunderScan uses an encoding scheme designed for |
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* 4-bit pixel values. Data is encoded in bytes, with |
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* each byte split into a 2-bit code word and a 6-bit |
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* data value. The encoding gives raw data, runs of |
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* pixels, or pixel values encoded as a delta from the |
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* previous pixel value. For the latter, either 2-bit |
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* or 3-bit delta values are used, with the deltas packed |
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* into a single byte. |
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*/ |
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#define THUNDER_DATA 0x3f /* mask for 6-bit data */ |
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#define THUNDER_CODE 0xc0 /* mask for 2-bit code word */ |
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/* code values */ |
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#define THUNDER_RUN 0x00 /* run of pixels w/ encoded count */ |
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#define THUNDER_2BITDELTAS 0x40 /* 3 pixels w/ encoded 2-bit deltas */ |
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#define DELTA2_SKIP 2 /* skip code for 2-bit deltas */ |
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#define THUNDER_3BITDELTAS 0x80 /* 2 pixels w/ encoded 3-bit deltas */ |
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#define DELTA3_SKIP 4 /* skip code for 3-bit deltas */ |
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#define THUNDER_RAW 0xc0 /* raw data encoded */ |
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static const int twobitdeltas[4] = { 0, 1, 0, -1 }; |
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static const int threebitdeltas[8] = { 0, 1, 2, 3, 0, -3, -2, -1 }; |
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#define SETPIXEL(op, v) { \ |
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lastpixel = (v) & 0xf; \ |
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if ( npixels < maxpixels ) \ |
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{ \ |
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if (npixels++ & 1) \ |
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*op++ |= lastpixel; \ |
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else \ |
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op[0] = (uint8) (lastpixel << 4); \ |
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} \ |
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} |
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static int |
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ThunderSetupDecode(TIFF* tif) |
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{ |
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static const char module[] = "ThunderSetupDecode"; |
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if( tif->tif_dir.td_bitspersample != 4 ) |
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{ |
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TIFFErrorExt(tif->tif_clientdata, module, |
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"Wrong bitspersample value (%d), Thunder decoder only supports 4bits per sample.", |
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(int) tif->tif_dir.td_bitspersample ); |
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return 0; |
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} |
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return (1); |
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} |
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static int |
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ThunderDecode(TIFF* tif, uint8* op, tmsize_t maxpixels) |
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{ |
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static const char module[] = "ThunderDecode"; |
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register unsigned char *bp; |
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register tmsize_t cc; |
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unsigned int lastpixel; |
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tmsize_t npixels; |
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bp = (unsigned char *)tif->tif_rawcp; |
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cc = tif->tif_rawcc; |
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lastpixel = 0; |
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npixels = 0; |
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while (cc > 0 && npixels < maxpixels) { |
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int n, delta; |
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n = *bp++; |
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cc--; |
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switch (n & THUNDER_CODE) { |
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case THUNDER_RUN: /* pixel run */ |
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/* |
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* Replicate the last pixel n times, |
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* where n is the lower-order 6 bits. |
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*/ |
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if (npixels & 1) { |
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op[0] |= lastpixel; |
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lastpixel = *op++; npixels++; n--; |
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} else |
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lastpixel |= lastpixel << 4; |
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npixels += n; |
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if (npixels < maxpixels) { |
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for (; n > 0; n -= 2) |
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*op++ = (uint8) lastpixel; |
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} |
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if (n == -1) |
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*--op &= 0xf0; |
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lastpixel &= 0xf; |
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break; |
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case THUNDER_2BITDELTAS: /* 2-bit deltas */ |
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if ((delta = ((n >> 4) & 3)) != DELTA2_SKIP) |
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SETPIXEL(op, (unsigned)((int)lastpixel + twobitdeltas[delta])); |
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if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP) |
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SETPIXEL(op, (unsigned)((int)lastpixel + twobitdeltas[delta])); |
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if ((delta = (n & 3)) != DELTA2_SKIP) |
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SETPIXEL(op, (unsigned)((int)lastpixel + twobitdeltas[delta])); |
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break; |
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case THUNDER_3BITDELTAS: /* 3-bit deltas */ |
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if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP) |
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SETPIXEL(op, (unsigned)((int)lastpixel + threebitdeltas[delta])); |
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if ((delta = (n & 7)) != DELTA3_SKIP) |
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SETPIXEL(op, (unsigned)((int)lastpixel + threebitdeltas[delta])); |
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break; |
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case THUNDER_RAW: /* raw data */ |
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SETPIXEL(op, n); |
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break; |
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} |
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} |
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tif->tif_rawcp = (uint8*) bp; |
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tif->tif_rawcc = cc; |
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if (npixels != maxpixels) { |
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#if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__)) |
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TIFFErrorExt(tif->tif_clientdata, module, |
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"%s data at scanline %lu (%I64u != %I64u)", |
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npixels < maxpixels ? "Not enough" : "Too much", |
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(unsigned long) tif->tif_row, |
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(unsigned __int64) npixels, |
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(unsigned __int64) maxpixels); |
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#else |
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TIFFErrorExt(tif->tif_clientdata, module, |
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"%s data at scanline %lu (%llu != %llu)", |
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npixels < maxpixels ? "Not enough" : "Too much", |
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(unsigned long) tif->tif_row, |
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(unsigned long long) npixels, |
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(unsigned long long) maxpixels); |
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#endif |
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return (0); |
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} |
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return (1); |
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} |
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static int |
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ThunderDecodeRow(TIFF* tif, uint8* buf, tmsize_t occ, uint16 s) |
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{ |
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static const char module[] = "ThunderDecodeRow"; |
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uint8* row = buf; |
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(void) s; |
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if (occ % tif->tif_scanlinesize) |
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{ |
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TIFFErrorExt(tif->tif_clientdata, module, "Fractional scanlines cannot be read"); |
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return (0); |
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} |
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while (occ > 0) { |
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if (!ThunderDecode(tif, row, tif->tif_dir.td_imagewidth)) |
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return (0); |
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occ -= tif->tif_scanlinesize; |
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row += tif->tif_scanlinesize; |
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} |
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return (1); |
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} |
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int |
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TIFFInitThunderScan(TIFF* tif, int scheme) |
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{ |
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(void) scheme; |
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tif->tif_setupdecode = ThunderSetupDecode; |
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tif->tif_decoderow = ThunderDecodeRow; |
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tif->tif_decodestrip = ThunderDecodeRow; |
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return (1); |
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} |
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#endif /* THUNDER_SUPPORT */ |
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/* vim: set ts=8 sts=8 sw=8 noet: */ |
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/* |
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* Local Variables: |
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* mode: c |
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* c-basic-offset: 8 |
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* fill-column: 78 |
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* End: |
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*/
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