src/tiff/tif_thunder.c

/* $Header$ */

/*
 * 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 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++ & 1) \
	    *op++ |= lastpixel; \
	else \
	    op[0] = lastpixel << 4; \
}

static int
ThunderDecode(TIFF* tif, tidata_t op, tsize_t maxpixels)
{
	register u_char *bp;
	register tsize_t cc;
	u_int lastpixel;
	tsize_t npixels;

	bp = (u_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 (npixels & 1) {
				op[0] |= lastpixel;
				lastpixel = *op++; npixels++; n--;
			} else
				lastpixel |= lastpixel << 4;
			npixels += n;
			for (; n > 0; n -= 2)
				*op++ = lastpixel;
			if (n == -1)
				*--op &= 0xf0;
			lastpixel &= 0xf;
			break;
		case THUNDER_2BITDELTAS:	/* 2-bit deltas */
			if ((delta = ((n >> 4) & 3)) != DELTA2_SKIP)
				SETPIXEL(op, lastpixel + twobitdeltas[delta]);
			if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP)
				SETPIXEL(op, lastpixel + twobitdeltas[delta]);
			if ((delta = (n & 3)) != DELTA2_SKIP)
				SETPIXEL(op, lastpixel + twobitdeltas[delta]);
			break;
		case THUNDER_3BITDELTAS:	/* 3-bit deltas */
			if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP)
				SETPIXEL(op, lastpixel + threebitdeltas[delta]);
			if ((delta = (n & 7)) != DELTA3_SKIP)
				SETPIXEL(op, lastpixel + threebitdeltas[delta]);
			break;
		case THUNDER_RAW:		/* raw data */
			SETPIXEL(op, n);
			break;
		}
	}
	tif->tif_rawcp = (tidata_t) bp;
	tif->tif_rawcc = cc;
	if (npixels != maxpixels) {
		TIFFError(tif->tif_name,
		    "ThunderDecode: %s data at scanline %ld (%lu != %lu)",
		    npixels < maxpixels ? "Not enough" : "Too much",
		    (long) tif->tif_row, (long) npixels, (long) maxpixels);
		return (0);
	}
	return (1);
}

static int
ThunderDecodeRow(TIFF* tif, tidata_t buf, tsize_t occ, tsample_t s)
{
	tidata_t row = buf;

	(void) s;
	while ((long)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_decoderow = ThunderDecodeRow;
	tif->tif_decodestrip = ThunderDecodeRow;
	return (1);
}
#endif /* THUNDER_SUPPORT */
Commit	Line	Data
	1	/* $Header$ */
	2
	3	/*
	4	* Copyright (c) 1988-1997 Sam Leffler
	5	* Copyright (c) 1991-1997 Silicon Graphics, Inc.
	6	*
	7	* Permission to use, copy, modify, distribute, and sell this software and
	8	* its documentation for any purpose is hereby granted without fee, provided
	9	* that (i) the above copyright notices and this permission notice appear in
	10	* all copies of the software and related documentation, and (ii) the names of
	11	* Sam Leffler and Silicon Graphics may not be used in any advertising or
	12	* publicity relating to the software without the specific, prior written
	13	* permission of Sam Leffler and Silicon Graphics.
	14	*
	15	* THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
	16	* EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
	17	* WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
	18	*
	19	* IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
	20	* ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
	21	* OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
	22	* WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
	23	* LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
	24	* OF THIS SOFTWARE.
	25	*/
	26
	27	#include "tiffiop.h"
	28	#ifdef THUNDER_SUPPORT
	29	/*
	30	* TIFF Library.
	31	*
	32	* ThunderScan 4-bit Compression Algorithm Support
	33	*/
	34
	35	/*
	36	* ThunderScan uses an encoding scheme designed for
	37	* 4-bit pixel values. Data is encoded in bytes, with
	38	* each byte split into a 2-bit code word and a 6-bit
	39	* data value. The encoding gives raw data, runs of
	40	* pixels, or pixel values encoded as a delta from the
	41	* previous pixel value. For the latter, either 2-bit
	42	* or 3-bit delta values are used, with the deltas packed
	43	* into a single byte.
	44	*/
	45	#define THUNDER_DATA 0x3f /* mask for 6-bit data */
	46	#define THUNDER_CODE 0xc0 /* mask for 2-bit code word */
	47	/* code values */
	48	#define THUNDER_RUN 0x00 /* run of pixels w/ encoded count */
	49	#define THUNDER_2BITDELTAS 0x40 /* 3 pixels w/ encoded 2-bit deltas */
	50	#define DELTA2_SKIP 2 /* skip code for 2-bit deltas */
	51	#define THUNDER_3BITDELTAS 0x80 /* 2 pixels w/ encoded 3-bit deltas */
	52	#define DELTA3_SKIP 4 /* skip code for 3-bit deltas */
	53	#define THUNDER_RAW 0xc0 /* raw data encoded */
	54
	55	static const int twobitdeltas[4] = { 0, 1, 0, -1 };
	56	static const int threebitdeltas[8] = { 0, 1, 2, 3, 0, -3, -2, -1 };
	57
	58	#define SETPIXEL(op, v) { \
	59	lastpixel = (v) & 0xf; \
	60	if (npixels++ & 1) \
	61	*op++ \|= lastpixel; \
	62	else \
	63	op[0] = lastpixel << 4; \
	64	}
	65
	66	static int
	67	ThunderDecode(TIFF* tif, tidata_t op, tsize_t maxpixels)
	68	{
	69	register u_char *bp;
	70	register tsize_t cc;
	71	u_int lastpixel;
	72	tsize_t npixels;
	73
	74	bp = (u_char *)tif->tif_rawcp;
	75	cc = tif->tif_rawcc;
	76	lastpixel = 0;
	77	npixels = 0;
	78	while (cc > 0 && npixels < maxpixels) {
	79	int n, delta;
	80
	81	n = *bp++, cc--;
	82	switch (n & THUNDER_CODE) {
	83	case THUNDER_RUN: /* pixel run */
	84	/*
	85	* Replicate the last pixel n times,
	86	* where n is the lower-order 6 bits.
	87	*/
	88	if (npixels & 1) {
	89	op[0] \|= lastpixel;
	90	lastpixel = *op++; npixels++; n--;
	91	} else
	92	lastpixel \|= lastpixel << 4;
	93	npixels += n;
	94	for (; n > 0; n -= 2)
	95	*op++ = lastpixel;
	96	if (n == -1)
	97	*--op &= 0xf0;
	98	lastpixel &= 0xf;
	99	break;
	100	case THUNDER_2BITDELTAS: /* 2-bit deltas */
	101	if ((delta = ((n >> 4) & 3)) != DELTA2_SKIP)
	102	SETPIXEL(op, lastpixel + twobitdeltas[delta]);
	103	if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP)
	104	SETPIXEL(op, lastpixel + twobitdeltas[delta]);
	105	if ((delta = (n & 3)) != DELTA2_SKIP)
	106	SETPIXEL(op, lastpixel + twobitdeltas[delta]);
	107	break;
	108	case THUNDER_3BITDELTAS: /* 3-bit deltas */
	109	if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP)
	110	SETPIXEL(op, lastpixel + threebitdeltas[delta]);
	111	if ((delta = (n & 7)) != DELTA3_SKIP)
	112	SETPIXEL(op, lastpixel + threebitdeltas[delta]);
	113	break;
	114	case THUNDER_RAW: /* raw data */
	115	SETPIXEL(op, n);
	116	break;
	117	}
	118	}
	119	tif->tif_rawcp = (tidata_t) bp;
	120	tif->tif_rawcc = cc;
	121	if (npixels != maxpixels) {
	122	TIFFError(tif->tif_name,
	123	"ThunderDecode: %s data at scanline %ld (%lu != %lu)",
	124	npixels < maxpixels ? "Not enough" : "Too much",
	125	(long) tif->tif_row, (long) npixels, (long) maxpixels);
	126	return (0);
	127	}
	128	return (1);
	129	}
	130
	131	static int
	132	ThunderDecodeRow(TIFF* tif, tidata_t buf, tsize_t occ, tsample_t s)
	133	{
	134	tidata_t row = buf;
	135
	136	(void) s;
	137	while ((long)occ > 0) {
	138	if (!ThunderDecode(tif, row, tif->tif_dir.td_imagewidth))
	139	return (0);
	140	occ -= tif->tif_scanlinesize;
	141	row += tif->tif_scanlinesize;
	142	}
	143	return (1);
	144	}
	145
	146	int
	147	TIFFInitThunderScan(TIFF* tif, int scheme)
	148	{
	149	(void) scheme;
	150	tif->tif_decoderow = ThunderDecodeRow;
	151	tif->tif_decodestrip = ThunderDecodeRow;
	152	return (1);
	153	}
	154	#endif /* THUNDER_SUPPORT */