Introduce a TextureDSP module
[libav.git] / libavcodec / s3tc.c
1 /*
2 * S3 Texture Compression (S3TC) decoding functions
3 * Copyright (c) 2007 by Ivo van Poorten
4 *
5 * see also: http://wiki.multimedia.cx/index.php?title=S3TC
6 *
7 * This file is part of Libav.
8 *
9 * Libav is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * Libav is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with Libav; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24 #include "avcodec.h"
25 #include "bytestream.h"
26 #include "s3tc.h"
27
28 static inline void dxt1_decode_pixels(GetByteContext *gb, uint32_t *d,
29 unsigned int qstride, unsigned int flag,
30 uint64_t alpha) {
31 unsigned int x, y, c0, c1, a = (!flag * 255u) << 24;
32 unsigned int rb0, rb1, rb2, rb3, g0, g1, g2, g3;
33 uint32_t colors[4], pixels;
34
35 c0 = bytestream2_get_le16(gb);
36 c1 = bytestream2_get_le16(gb);
37
38 rb0 = (c0<<3 | c0<<8) & 0xf800f8;
39 rb1 = (c1<<3 | c1<<8) & 0xf800f8;
40 rb0 += (rb0>>5) & 0x070007;
41 rb1 += (rb1>>5) & 0x070007;
42 g0 = (c0 <<5) & 0x00fc00;
43 g1 = (c1 <<5) & 0x00fc00;
44 g0 += (g0 >>6) & 0x000300;
45 g1 += (g1 >>6) & 0x000300;
46
47 colors[0] = rb0 + g0 + a;
48 colors[1] = rb1 + g1 + a;
49
50 if (c0 > c1 || flag) {
51 rb2 = (((2*rb0+rb1) * 21) >> 6) & 0xff00ff;
52 rb3 = (((2*rb1+rb0) * 21) >> 6) & 0xff00ff;
53 g2 = (((2*g0 +g1 ) * 21) >> 6) & 0x00ff00;
54 g3 = (((2*g1 +g0 ) * 21) >> 6) & 0x00ff00;
55 colors[3] = rb3 + g3 + a;
56 } else {
57 rb2 = ((rb0+rb1) >> 1) & 0xff00ff;
58 g2 = ((g0 +g1 ) >> 1) & 0x00ff00;
59 colors[3] = 0;
60 }
61
62 colors[2] = rb2 + g2 + a;
63
64 pixels = bytestream2_get_le32(gb);
65 for (y=0; y<4; y++) {
66 for (x=0; x<4; x++) {
67 a = (alpha & 0x0f) << 28;
68 a += a >> 4;
69 d[x] = a + colors[pixels&3];
70 pixels >>= 2;
71 alpha >>= 4;
72 }
73 d += qstride;
74 }
75 }
76
77 void ff_decode_dxt1(GetByteContext *gb, uint8_t *dst,
78 const unsigned int w, const unsigned int h,
79 const unsigned int stride) {
80 unsigned int bx, by, qstride = stride/4;
81 uint32_t *d = (uint32_t *) dst;
82
83 for (by=0; by < h/4; by++, d += stride-w)
84 for (bx = 0; bx < w / 4; bx++, d += 4)
85 dxt1_decode_pixels(gb, d, qstride, 0, 0LL);
86 }
87
88 void ff_decode_dxt3(GetByteContext *gb, uint8_t *dst,
89 const unsigned int w, const unsigned int h,
90 const unsigned int stride) {
91 unsigned int bx, by, qstride = stride/4;
92 uint32_t *d = (uint32_t *) dst;
93
94 for (by=0; by < h/4; by++, d += stride-w)
95 for (bx = 0; bx < w / 4; bx++, d += 4)
96 dxt1_decode_pixels(gb, d, qstride, 1, bytestream2_get_le64(gb));
97 }