File: tif_thunder.c

package info (click to toggle)
gamera 1:3.4.2+git20160808.1725654-1
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 22,312 kB
  • ctags: 24,991
  • sloc: xml: 122,324; ansic: 52,869; cpp: 50,664; python: 35,034; makefile: 118; sh: 101
file content (154 lines) | stat: -rw-r--r-- 4,750 bytes parent folder | download | duplicates (4)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
/* $Header$ */

/*
 * 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 */