path: root/tif_thunder.c (plain)
blob: 390891c98bde1a07c593e6560f754826f656f11a

1	/* $Id: tif_thunder.c,v 1.12 2011-04-02 20:54:09 bfriesen Exp $ */
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	#include <assert.h>
29	#ifdef THUNDER_SUPPORT
30	/*
31	* TIFF Library.
32	*
33	* ThunderScan 4-bit Compression Algorithm Support
34	*/
35
36	/*
37	* ThunderScan uses an encoding scheme designed for
38	* 4-bit pixel values. Data is encoded in bytes, with
39	* each byte split into a 2-bit code word and a 6-bit
40	* data value. The encoding gives raw data, runs of
41	* pixels, or pixel values encoded as a delta from the
42	* previous pixel value. For the latter, either 2-bit
43	* or 3-bit delta values are used, with the deltas packed
44	* into a single byte.
45	*/
46	#define THUNDER_DATA 0x3f /* mask for 6-bit data */
47	#define THUNDER_CODE 0xc0 /* mask for 2-bit code word */
48	/* code values */
49	#define THUNDER_RUN 0x00 /* run of pixels w/ encoded count */
50	#define THUNDER_2BITDELTAS 0x40 /* 3 pixels w/ encoded 2-bit deltas */
51	#define DELTA2_SKIP 2 /* skip code for 2-bit deltas */
52	#define THUNDER_3BITDELTAS 0x80 /* 2 pixels w/ encoded 3-bit deltas */
53	#define DELTA3_SKIP 4 /* skip code for 3-bit deltas */
54	#define THUNDER_RAW 0xc0 /* raw data encoded */
55
56	static const int twobitdeltas[4] = { 0, 1, 0, -1 };
57	static const int threebitdeltas[8] = { 0, 1, 2, 3, 0, -3, -2, -1 };
58
59	#define SETPIXEL(op, v) { \
60	lastpixel = (v) & 0xf; \
61	if ( npixels < maxpixels ) \
62	{ \
63	if (npixels++ & 1) \
64	*op++ |= lastpixel; \
65	else \
66	op[0] = (uint8) (lastpixel << 4); \
67	} \
68	}
69
70	static int
71	ThunderSetupDecode(TIFF* tif)
72	{
73	static const char module[] = "ThunderSetupDecode";
74
75	if( tif->tif_dir.td_bitspersample != 4 )
76	{
77	TIFFErrorExt(tif->tif_clientdata, module,
78	"Wrong bitspersample value (%d), Thunder decoder only supports 4bits per sample.",
79	(int) tif->tif_dir.td_bitspersample );
80	return 0;
81	}
82
83
84	return (1);
85	}
86
87	static int
88	ThunderDecode(TIFF* tif, uint8* op, tmsize_t maxpixels)
89	{
90	static const char module[] = "ThunderDecode";
91	register unsigned char *bp;
92	register tmsize_t cc;
93	unsigned int lastpixel;
94	tmsize_t npixels;
95
96	bp = (unsigned char *)tif->tif_rawcp;
97	cc = tif->tif_rawcc;
98	lastpixel = 0;
99	npixels = 0;
100	while (cc > 0 && npixels < maxpixels) {
101	int n, delta;
102
103	n = *bp++, cc--;
104	switch (n & THUNDER_CODE) {
105	case THUNDER_RUN: /* pixel run */
106	/*
107	* Replicate the last pixel n times,
108	* where n is the lower-order 6 bits.
109	*/
110	if (npixels & 1) {
111	op[0] |= lastpixel;
112	lastpixel = *op++; npixels++; n--;
113	} else
114	lastpixel |= lastpixel << 4;
115	npixels += n;
116	if (npixels < maxpixels) {
117	for (; n > 0; n -= 2)
118	*op++ = (uint8) lastpixel;
119	}
120	if (n == -1)
121	*--op &= 0xf0;
122	lastpixel &= 0xf;
123	break;
124	case THUNDER_2BITDELTAS: /* 2-bit deltas */
125	if ((delta = ((n >> 4) & 3)) != DELTA2_SKIP)
126	SETPIXEL(op, lastpixel + twobitdeltas[delta]);
127	if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP)
128	SETPIXEL(op, lastpixel + twobitdeltas[delta]);
129	if ((delta = (n & 3)) != DELTA2_SKIP)
130	SETPIXEL(op, lastpixel + twobitdeltas[delta]);
131	break;
132	case THUNDER_3BITDELTAS: /* 3-bit deltas */
133	if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP)
134	SETPIXEL(op, lastpixel + threebitdeltas[delta]);
135	if ((delta = (n & 7)) != DELTA3_SKIP)
136	SETPIXEL(op, lastpixel + threebitdeltas[delta]);
137	break;
138	case THUNDER_RAW: /* raw data */
139	SETPIXEL(op, n);
140	break;
141	}
142	}
143	tif->tif_rawcp = (uint8*) bp;
144	tif->tif_rawcc = cc;
145	if (npixels != maxpixels) {
146	#if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
147	TIFFErrorExt(tif->tif_clientdata, module,
148	"%s data at scanline %lu (%I64u != %I64u)",
149	npixels < maxpixels ? "Not enough" : "Too much",
150	(unsigned long) tif->tif_row,
151	(unsigned __int64) npixels,
152	(unsigned __int64) maxpixels);
153	#else
154	TIFFErrorExt(tif->tif_clientdata, module,
155	"%s data at scanline %lu (%llu != %llu)",
156	npixels < maxpixels ? "Not enough" : "Too much",
157	(unsigned long) tif->tif_row,
158	(unsigned long long) npixels,
159	(unsigned long long) maxpixels);
160	#endif
161	return (0);
162	}
163
164	return (1);
165	}
166
167	static int
168	ThunderDecodeRow(TIFF* tif, uint8* buf, tmsize_t occ, uint16 s)
169	{
170	static const char module[] = "ThunderDecodeRow";
171	uint8* row = buf;
172
173	(void) s;
174	if (occ % tif->tif_scanlinesize)
175	{
176	TIFFErrorExt(tif->tif_clientdata, module, "Fractional scanlines cannot be read");
177	return (0);
178	}
179	while (occ > 0) {
180	if (!ThunderDecode(tif, row, tif->tif_dir.td_imagewidth))
181	return (0);
182	occ -= tif->tif_scanlinesize;
183	row += tif->tif_scanlinesize;
184	}
185	return (1);
186	}
187
188	int
189	TIFFInitThunderScan(TIFF* tif, int scheme)
190	{
191	(void) scheme;
192
193	tif->tif_setupdecode = ThunderSetupDecode;
194	tif->tif_decoderow = ThunderDecodeRow;
195	tif->tif_decodestrip = ThunderDecodeRow;
196	return (1);
197	}
198	#endif /* THUNDER_SUPPORT */
199
200	/* vim: set ts=8 sts=8 sw=8 noet: */
201	/*
202	* Local Variables:
203	* mode: c
204	* c-basic-offset: 8
205	* fill-column: 78
206	* End:
207	*/
208