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207 lines
6.2 KiB
C
207 lines
6.2 KiB
C
/*
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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, lastpixel + twobitdeltas[delta]);
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if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP)
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SETPIXEL(op, lastpixel + twobitdeltas[delta]);
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if ((delta = (n & 3)) != DELTA2_SKIP)
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SETPIXEL(op, 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, lastpixel + threebitdeltas[delta]);
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if ((delta = (n & 7)) != DELTA3_SKIP)
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SETPIXEL(op, 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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