Libav 0.7.1
|
00001 /* 00002 * S3 Texture Compression (S3TC) decoding functions 00003 * Copyright (c) 2007 by Ivo van Poorten 00004 * 00005 * see also: http://wiki.multimedia.cx/index.php?title=S3TC 00006 * 00007 * This file is part of Libav. 00008 * 00009 * Libav is free software; you can redistribute it and/or 00010 * modify it under the terms of the GNU Lesser General Public 00011 * License as published by the Free Software Foundation; either 00012 * version 2.1 of the License, or (at your option) any later version. 00013 * 00014 * Libav is distributed in the hope that it will be useful, 00015 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00016 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00017 * Lesser General Public License for more details. 00018 * 00019 * You should have received a copy of the GNU Lesser General Public 00020 * License along with Libav; if not, write to the Free Software 00021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00022 */ 00023 00024 #include "libavutil/intreadwrite.h" 00025 #include "avcodec.h" 00026 #include "s3tc.h" 00027 00028 static inline void dxt1_decode_pixels(const uint8_t *s, uint32_t *d, 00029 unsigned int qstride, unsigned int flag, 00030 uint64_t alpha) { 00031 unsigned int x, y, c0, c1, a = (!flag * 255) << 24; 00032 unsigned int rb0, rb1, rb2, rb3, g0, g1, g2, g3; 00033 uint32_t colors[4], pixels; 00034 00035 c0 = AV_RL16(s); 00036 c1 = AV_RL16(s+2); 00037 00038 rb0 = (c0<<3 | c0<<8) & 0xf800f8; 00039 rb1 = (c1<<3 | c1<<8) & 0xf800f8; 00040 rb0 += (rb0>>5) & 0x070007; 00041 rb1 += (rb1>>5) & 0x070007; 00042 g0 = (c0 <<5) & 0x00fc00; 00043 g1 = (c1 <<5) & 0x00fc00; 00044 g0 += (g0 >>6) & 0x000300; 00045 g1 += (g1 >>6) & 0x000300; 00046 00047 colors[0] = rb0 + g0 + a; 00048 colors[1] = rb1 + g1 + a; 00049 00050 if (c0 > c1 || flag) { 00051 rb2 = (((2*rb0+rb1) * 21) >> 6) & 0xff00ff; 00052 rb3 = (((2*rb1+rb0) * 21) >> 6) & 0xff00ff; 00053 g2 = (((2*g0 +g1 ) * 21) >> 6) & 0x00ff00; 00054 g3 = (((2*g1 +g0 ) * 21) >> 6) & 0x00ff00; 00055 colors[3] = rb3 + g3 + a; 00056 } else { 00057 rb2 = ((rb0+rb1) >> 1) & 0xff00ff; 00058 g2 = ((g0 +g1 ) >> 1) & 0x00ff00; 00059 colors[3] = 0; 00060 } 00061 00062 colors[2] = rb2 + g2 + a; 00063 00064 pixels = AV_RL32(s+4); 00065 for (y=0; y<4; y++) { 00066 for (x=0; x<4; x++) { 00067 a = (alpha & 0x0f) << 28; 00068 a += a >> 4; 00069 d[x] = a + colors[pixels&3]; 00070 pixels >>= 2; 00071 alpha >>= 4; 00072 } 00073 d += qstride; 00074 } 00075 } 00076 00077 void ff_decode_dxt1(const uint8_t *s, uint8_t *dst, 00078 const unsigned int w, const unsigned int h, 00079 const unsigned int stride) { 00080 unsigned int bx, by, qstride = stride/4; 00081 uint32_t *d = (uint32_t *) dst; 00082 00083 for (by=0; by < h/4; by++, d += stride-w) 00084 for (bx=0; bx < w/4; bx++, s+=8, d+=4) 00085 dxt1_decode_pixels(s, d, qstride, 0, 0LL); 00086 } 00087 00088 void ff_decode_dxt3(const uint8_t *s, uint8_t *dst, 00089 const unsigned int w, const unsigned int h, 00090 const unsigned int stride) { 00091 unsigned int bx, by, qstride = stride/4; 00092 uint32_t *d = (uint32_t *) dst; 00093 00094 for (by=0; by < h/4; by++, d += stride-w) 00095 for (bx=0; bx < w/4; bx++, s+=16, d+=4) 00096 dxt1_decode_pixels(s+8, d, qstride, 1, AV_RL64(s)); 00097 }