00734d7d108d778542cc364b42d15c58cb6ba8b5
[libav.git] / libavcodec / pngdsp.c
1 /*
2 * PNG image format
3 * Copyright (c) 2008 Loren Merrit <lorenm@u.washington.edu>
4 *
5 * This file is part of Libav.
6 *
7 * Libav is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * Libav is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include "libavutil/common.h"
23 #include "png.h"
24 #include "pngdsp.h"
25
26 // 0x7f7f7f7f or 0x7f7f7f7f7f7f7f7f or whatever, depending on the cpu's native arithmetic size
27 #define pb_7f (~0UL/255 * 0x7f)
28 #define pb_80 (~0UL/255 * 0x80)
29
30 static void add_bytes_l2_c(uint8_t *dst, uint8_t *src1, uint8_t *src2, int w)
31 {
32 long i;
33 for (i = 0; i <= w - sizeof(long); i += sizeof(long)) {
34 long a = *(long *)(src1 + i);
35 long b = *(long *)(src2 + i);
36 *(long *)(dst + i) = ((a & pb_7f) + (b & pb_7f)) ^ ((a ^ b) & pb_80);
37 }
38 for (; i < w; i++)
39 dst[i] = src1[i] + src2[i];
40 }
41
42 void ff_pngdsp_init(PNGDSPContext *dsp)
43 {
44 dsp->add_bytes_l2 = add_bytes_l2_c;
45 dsp->add_paeth_prediction = ff_add_png_paeth_prediction;
46
47 if (ARCH_X86) ff_pngdsp_init_x86(dsp);
48 }