FFmpeg
 All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
pngdsp.c
Go to the documentation of this file.
1 /*
2  * PNG image format
3  * Copyright (c) 2008 Loren Merrit <lorenm@u.washington.edu>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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 
43 {
46 
47  if (ARCH_X86) ff_pngdsp_init_x86(dsp);
48 }