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/* $Header: /cvsroot/osrs/libtiff/libtiff/tif_packbits.c,v 1.7 2003/07/08 16:40:46 warmerda Exp $ */
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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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* 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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* 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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* 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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#ifdef PACKBITS_SUPPORT
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* PackBits Compression Algorithm Support
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PackBitsPreEncode(TIFF* tif, tsample_t s)
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* Calculate the scanline/tile-width size in bytes.
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tif->tif_data = (tidata_t) TIFFTileRowSize(tif);
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tif->tif_data = (tidata_t) TIFFScanlineSize(tif);
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* NB: tidata is the type representing *(tidata_t);
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* if tidata_t is made signed then this type must
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* be adjusted accordingly.
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typedef unsigned char tidata;
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* Encode a run of pixels.
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PackBitsEncode(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
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u_char* bp = (u_char*) buf;
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tidata_t op, ep, lastliteral;
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enum { BASE, LITERAL, RUN, LITERAL_RUN } state;
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ep = tif->tif_rawdata + tif->tif_rawdatasize;
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* Find the longest string of identical bytes.
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b = *bp++, cc--, n = 1;
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for (; cc > 0 && b == *bp; cc--, bp++)
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if (op + 2 >= ep) { /* insure space for new data */
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* Be careful about writing the last
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* literal. Must write up to that point
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* and then copy the remainder to the
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* front of the buffer.
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if (state == LITERAL || state == LITERAL_RUN) {
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slop = op - lastliteral;
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tif->tif_rawcc += lastliteral - tif->tif_rawcp;
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if (!TIFFFlushData1(tif))
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*op++ = *lastliteral++;
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lastliteral = tif->tif_rawcp;
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tif->tif_rawcc += op - tif->tif_rawcp;
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if (!TIFFFlushData1(tif))
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case BASE: /* initial state, set run/literal */
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*op++ = (tidata) -127;
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*op++ = (tidataval_t) b;
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*op++ = (tidataval_t)(-(n-1));
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*op++ = (tidataval_t) b;
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*op++ = (tidataval_t) b;
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case LITERAL: /* last object was literal string */
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*op++ = (tidata) -127;
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*op++ = (tidataval_t) b;
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*op++ = (tidataval_t)(-(n-1)); /* encode run */
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*op++ = (tidataval_t) b;
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} else { /* extend literal */
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if (++(*lastliteral) == 127)
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*op++ = (tidataval_t) b;
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case RUN: /* last object was run */
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*op++ = (tidata) -127;
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*op++ = (tidataval_t) b;
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*op++ = (tidataval_t)(-(n-1));
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*op++ = (tidataval_t) b;
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*op++ = (tidataval_t) b;
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case LITERAL_RUN: /* literal followed by a run */
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* Check to see if previous run should
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* be converted to a literal, in which
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* case we convert literal-run-literal
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* to a single literal.
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if (n == 1 && op[-2] == (tidata) -1 &&
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*lastliteral < 126) {
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state = (((*lastliteral) += 2) == 127 ?
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op[-2] = op[-1]; /* replicate */
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tif->tif_rawcc += op - tif->tif_rawcp;
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* Encode a rectangular chunk of pixels. We break it up
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* into row-sized pieces to insure that encoded runs do
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* not span rows. Otherwise, there can be problems with
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* the decoder if data is read, for example, by scanlines
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* when it was encoded by strips.
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PackBitsEncodeChunk(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
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#if defined(__hpux) && defined(__LP64__)
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tsize_t rowsize = (tsize_t)(unsigned long) tif->tif_data;
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tsize_t rowsize = (tsize_t) tif->tif_data;
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* YCBCR data isn't really separable into rows, so we
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* might as well encode the whole tile/strip as one chunk.
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if( tif->tif_dir.td_photometric == PHOTOMETRIC_YCBCR ) {
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#if defined(__hpux) && defined(__LP64__)
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rowsize = (tsize_t)(unsigned long) tif->tif_data;
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rowsize = (tsize_t) tif->tif_data;
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while ((long)cc > 0) {
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if (PackBitsEncode(tif, bp, chunk, s) < 0)
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PackBitsDecode(TIFF* tif, tidata_t op, tsize_t occ, tsample_t s)
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bp = (char*) tif->tif_rawcp;
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while (cc > 0 && (long)occ > 0) {
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n = (long) *bp++, cc--;
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* Watch out for compilers that
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* don't sign extend chars...
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if (n < 0) { /* replicate next byte -n+1 times */
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if (n == -128) /* nop */
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TIFFWarning(tif->tif_name,
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"PackBitsDecode: discarding %d bytes "
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"to avoid buffer overrun",
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*op++ = (tidataval_t) b;
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} else { /* copy next n+1 bytes literally */
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TIFFWarning(tif->tif_name,
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"PackBitsDecode: discarding %d bytes "
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"to avoid buffer overrun",
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_TIFFmemcpy(op, bp, ++n);
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tif->tif_rawcp = (tidata_t) bp;
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TIFFError(tif->tif_name,
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"PackBitsDecode: Not enough data for scanline %ld",
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(long) tif->tif_row);
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TIFFInitPackBits(TIFF* tif, int scheme)
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tif->tif_decoderow = PackBitsDecode;
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tif->tif_decodestrip = PackBitsDecode;
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tif->tif_decodetile = PackBitsDecode;
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tif->tif_preencode = PackBitsPreEncode;
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tif->tif_encoderow = PackBitsEncode;
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tif->tif_encodestrip = PackBitsEncodeChunk;
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tif->tif_encodetile = PackBitsEncodeChunk;
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#endif /* PACKBITS_SUPPORT */
added
removed
libtiff/tif_packbits.c
