523fd17ea63ca86525573d51be04e2dbdcadb06e
1 /* $Id: tif_thunder.c,v 1.13 2016-09-04 21:32:56 erouault Exp $ */
4 * Copyright (c) 1988-1997 Sam Leffler
5 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
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.
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.
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
30 #ifdef THUNDER_SUPPORT
34 * ThunderScan 4-bit Compression Algorithm Support
38 * ThunderScan uses an encoding scheme designed for
39 * 4-bit pixel values. Data is encoded in bytes, with
40 * each byte split into a 2-bit code word and a 6-bit
41 * data value. The encoding gives raw data, runs of
42 * pixels, or pixel values encoded as a delta from the
43 * previous pixel value. For the latter, either 2-bit
44 * or 3-bit delta values are used, with the deltas packed
47 #define THUNDER_DATA 0x3f /* mask for 6-bit data */
48 #define THUNDER_CODE 0xc0 /* mask for 2-bit code word */
50 #define THUNDER_RUN 0x00 /* run of pixels w/ encoded count */
51 #define THUNDER_2BITDELTAS 0x40 /* 3 pixels w/ encoded 2-bit deltas */
52 #define DELTA2_SKIP 2 /* skip code for 2-bit deltas */
53 #define THUNDER_3BITDELTAS 0x80 /* 2 pixels w/ encoded 3-bit deltas */
54 #define DELTA3_SKIP 4 /* skip code for 3-bit deltas */
55 #define THUNDER_RAW 0xc0 /* raw data encoded */
57 static const int twobitdeltas
[4] = { 0, 1, 0, -1 };
58 static const int threebitdeltas
[8] = { 0, 1, 2, 3, 0, -3, -2, -1 };
60 #define SETPIXEL(op, v) { \
61 lastpixel = (v) & 0xf; \
62 if ( npixels < maxpixels ) \
67 op[0] = (uint8) (lastpixel << 4); \
72 ThunderSetupDecode(TIFF
* tif
)
74 static const char module
[] = "ThunderSetupDecode";
76 if( tif
->tif_dir
.td_bitspersample
!= 4 )
78 TIFFErrorExt(tif
->tif_clientdata
, module
,
79 "Wrong bitspersample value (%d), Thunder decoder only supports 4bits per sample.",
80 (int) tif
->tif_dir
.td_bitspersample
);
89 ThunderDecode(TIFF
* tif
, uint8
* op
, tmsize_t maxpixels
)
91 static const char module
[] = "ThunderDecode";
92 register unsigned char *bp
;
94 unsigned int lastpixel
;
97 bp
= (unsigned char *)tif
->tif_rawcp
;
101 while (cc
> 0 && npixels
< maxpixels
) {
106 switch (n
& THUNDER_CODE
) {
107 case THUNDER_RUN
: /* pixel run */
109 * Replicate the last pixel n times,
110 * where n is the lower-order 6 bits.
114 lastpixel
= *op
++; npixels
++; n
--;
116 lastpixel
|= lastpixel
<< 4;
118 if (npixels
< maxpixels
) {
119 for (; n
> 0; n
-= 2)
120 *op
++ = (uint8
) lastpixel
;
126 case THUNDER_2BITDELTAS
: /* 2-bit deltas */
127 if ((delta
= ((n
>> 4) & 3)) != DELTA2_SKIP
)
128 SETPIXEL(op
, lastpixel
+ twobitdeltas
[delta
]);
129 if ((delta
= ((n
>> 2) & 3)) != DELTA2_SKIP
)
130 SETPIXEL(op
, lastpixel
+ twobitdeltas
[delta
]);
131 if ((delta
= (n
& 3)) != DELTA2_SKIP
)
132 SETPIXEL(op
, lastpixel
+ twobitdeltas
[delta
]);
134 case THUNDER_3BITDELTAS
: /* 3-bit deltas */
135 if ((delta
= ((n
>> 3) & 7)) != DELTA3_SKIP
)
136 SETPIXEL(op
, lastpixel
+ threebitdeltas
[delta
]);
137 if ((delta
= (n
& 7)) != DELTA3_SKIP
)
138 SETPIXEL(op
, lastpixel
+ threebitdeltas
[delta
]);
140 case THUNDER_RAW
: /* raw data */
145 tif
->tif_rawcp
= (uint8
*) bp
;
147 if (npixels
!= maxpixels
) {
148 #if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
149 TIFFErrorExt(tif
->tif_clientdata
, module
,
150 "%s data at scanline %lu (%I64u != %I64u)",
151 npixels
< maxpixels
? "Not enough" : "Too much",
152 (unsigned long) tif
->tif_row
,
153 (unsigned __int64
) npixels
,
154 (unsigned __int64
) maxpixels
);
156 TIFFErrorExt(tif
->tif_clientdata
, module
,
157 "%s data at scanline %lu (%llu != %llu)",
158 npixels
< maxpixels
? "Not enough" : "Too much",
159 (unsigned long) tif
->tif_row
,
160 (unsigned long long) npixels
,
161 (unsigned long long) maxpixels
);
170 ThunderDecodeRow(TIFF
* tif
, uint8
* buf
, tmsize_t occ
, uint16 s
)
172 static const char module
[] = "ThunderDecodeRow";
176 if (occ
% tif
->tif_scanlinesize
)
178 TIFFErrorExt(tif
->tif_clientdata
, module
, "Fractional scanlines cannot be read");
182 if (!ThunderDecode(tif
, row
, tif
->tif_dir
.td_imagewidth
))
184 occ
-= tif
->tif_scanlinesize
;
185 row
+= tif
->tif_scanlinesize
;
191 TIFFInitThunderScan(TIFF
* tif
, int scheme
)
195 tif
->tif_setupdecode
= ThunderSetupDecode
;
196 tif
->tif_decoderow
= ThunderDecodeRow
;
197 tif
->tif_decodestrip
= ThunderDecodeRow
;
200 #endif /* THUNDER_SUPPORT */
202 /* vim: set ts=8 sts=8 sw=8 noet: */