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vendor: OpenCV 5.0.0 snapshot at 40738fb16ceddb5fb3fea747585f7ce6abb0605b

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2026-08-22 00:10:33 +08:00
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3rdparty/libtiff/tif_thunder.c
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/*
* 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 *op0, tmsize_t maxpixels)
{
static const char module[] = "ThunderDecode";
register unsigned char *bp;
register tmsize_t cc;
unsigned int lastpixel;
tmsize_t npixels;
uint8_t *op = op0;
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 (n == 0)
break;
if (npixels & 1)
{
op[0] |= lastpixel;
lastpixel = *op++;
npixels++;
n--;
}
else
lastpixel |= lastpixel << 4;
npixels += n;
if (npixels > maxpixels)
break;
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)
{
uint8_t *op_end = op0 + (maxpixels + 1) / 2;
memset(op, 0, (size_t)(op_end - op));
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 */