/* $Header: /cvsroot/osrs/libtiff/libtiff/tif_packbits.c,v 1.5 2001/09/06 19:28:45 warmerda 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 PACKBITS_SUPPORT
/*
* TIFF Library.
*
* PackBits Compression Algorithm Support
*/
#include <assert.h>
#include <stdio.h>
static int
PackBitsPreEncode(TIFF* tif, tsample_t s)
{
(void) s;
/*
* Calculate the scanline/tile-width size in bytes.
*/
if (isTiled(tif))
tif->tif_data = (tidata_t) TIFFTileRowSize(tif);
else
tif->tif_data = (tidata_t) TIFFScanlineSize(tif);
return (1);
}
/*
* NB: tidata is the type representing *(tidata_t);
* if tidata_t is made signed then this type must
* be adjusted accordingly.
*/
typedef unsigned char tidata;
/*
* Encode a run of pixels.
*/
static int
PackBitsEncode(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
{
u_char* bp = (u_char*) buf;
tidata_t op, ep, lastliteral;
long n, slop;
int b;
enum { BASE, LITERAL, RUN, LITERAL_RUN } state;
(void) s;
op = tif->tif_rawcp;
ep = tif->tif_rawdata + tif->tif_rawdatasize;
state = BASE;
lastliteral = 0;
while (cc > 0) {
/*
* Find the longest string of identical bytes.
*/
b = *bp++, cc--, n = 1;
for (; cc > 0 && b == *bp; cc--, bp++)
n++;
again:
if (op + 2 >= ep) { /* insure space for new data */
/*
* Be careful about writing the last
* literal. Must write up to that point
* and then copy the remainder to the
* front of the buffer.
*/
if (state == LITERAL || state == LITERAL_RUN) {
slop = op - lastliteral;
tif->tif_rawcc += lastliteral - tif->tif_rawcp;
if (!TIFFFlushData1(tif))
return (-1);
op = tif->tif_rawcp;
while (slop-- > 0)
*op++ = *lastliteral++;
lastliteral = tif->tif_rawcp;
} else {
tif->tif_rawcc += op - tif->tif_rawcp;
if (!TIFFFlushData1(tif))
return (-1);
op = tif->tif_rawcp;
}
}
switch (state) {
case BASE: /* initial state, set run/literal */
if (n > 1) {
state = RUN;
if (n > 128) {
*op++ = (tidata) -127;
*op++ = b;
n -= 128;
goto again;
}
*op++ = (tidataval_t)(-(n-1));
*op++ = b;
} else {
lastliteral = op;
*op++ = 0;
*op++ = b;
state = LITERAL;
}
break;
case LITERAL: /* last object was literal string */
if (n > 1) {
state = LITERAL_RUN;
if (n > 128) {
*op++ = (tidata) -127;
*op++ = b;
n -= 128;
goto again;
}
*op++ = (tidataval_t)(-(n-1)); /* encode run */
*op++ = b;
} else { /* extend literal */
if (++(*lastliteral) == 127)
state = BASE;
*op++ = b;
}
break;
case RUN: /* last object was run */
if (n > 1) {
if (n > 128) {
*op++ = (tidata) -127;
*op++ = b;
n -= 128;
goto again;
}
*op++ = (tidataval_t)(-(n-1));
*op++ = b;
} else {
lastliteral = op;
*op++ = 0;
*op++ = b;
state = LITERAL;
}
break;
case LITERAL_RUN: /* literal followed by a run */
/*
* Check to see if previous run should
* be converted to a literal, in which
* case we convert literal-run-literal
* to a single literal.
*/
if (n == 1 && op[-2] == (tidata) -1 &&
*lastliteral < 126) {
state = (((*lastliteral) += 2) == 127 ?
BASE : LITERAL);
op[-2] = op[-1]; /* replicate */
} else
state = RUN;
goto again;
}
}
tif->tif_rawcc += op - tif->tif_rawcp;
tif->tif_rawcp = op;
return (1);
}
/*
* Encode a rectangular chunk of pixels. We break it up
* into row-sized pieces to insure that encoded runs do
* not span rows. Otherwise, there can be problems with
* the decoder if data is read, for example, by scanlines
* when it was encoded by strips.
*/
static int
PackBitsEncodeChunk(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
{
tsize_t rowsize = (tsize_t) tif->tif_data;
assert(rowsize > 0);
#ifdef YCBCR_SUPPORT
/*
* YCBCR data isn't really separable into rows, so we
* might as well encode the whole tile/strip as one chunk.
*/
if( tif->tif_dir.td_photometric == PHOTOMETRIC_YCBCR )
rowsize = (tsize_t) tif->tif_data;
#endif
while ((long)cc > 0) {
int chunk = rowsize;
if( cc < chunk )
chunk = cc;
if (PackBitsEncode(tif, bp, chunk, s) < 0)
return (-1);
bp += chunk;
cc -= chunk;
}
return (1);
}
static int
PackBitsDecode(TIFF* tif, tidata_t op, tsize_t occ, tsample_t s)
{
char *bp;
tsize_t cc;
long n;
int b;
(void) s;
bp = (char*) tif->tif_rawcp;
cc = tif->tif_rawcc;
while (cc > 0 && (long)occ > 0) {
n = (long) *bp++, cc--;
/*
* Watch out for compilers that
* don't sign extend chars...
*/
if (n >= 128)
n -= 256;
if (n < 0) { /* replicate next byte -n+1 times */
if (n == -128) /* nop */
continue;
n = -n + 1;
if( occ < n )
{
TIFFWarning(tif->tif_name,
"PackBitsDecode: discarding %d bytes "
"to avoid buffer overrun",
n - occ);
n = occ;
}
occ -= n;
b = *bp++, cc--;
while (n-- > 0)
*op++ = b;
} else { /* copy next n+1 bytes literally */
if (occ < n + 1)
{
TIFFWarning(tif->tif_name,
"PackBitsDecode: discarding %d bytes "
"to avoid buffer overrun",
n - occ + 1);
n = occ - 1;
}
_TIFFmemcpy(op, bp, ++n);
op += n; occ -= n;
bp += n; cc -= n;
}
}
tif->tif_rawcp = (tidata_t) bp;
tif->tif_rawcc = cc;
if (occ > 0) {
TIFFError(tif->tif_name,
"PackBitsDecode: Not enough data for scanline %ld",
(long) tif->tif_row);
return (0);
}
return (1);
}
int
TIFFInitPackBits(TIFF* tif, int scheme)
{
(void) scheme;
tif->tif_decoderow = PackBitsDecode;
tif->tif_decodestrip = PackBitsDecode;
tif->tif_decodetile = PackBitsDecode;
tif->tif_preencode = PackBitsPreEncode;
tif->tif_encoderow = PackBitsEncode;
tif->tif_encodestrip = PackBitsEncodeChunk;
tif->tif_encodetile = PackBitsEncodeChunk;
return (1);
}
#endif /* PACKBITS_SUPPORT */
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