FFmpeg
rnd_avg.h
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1 /*
2  * Copyright (c) 2001-2003 BERO <bero@geocities.co.jp>
3  * Copyright (c) 2011 Oskar Arvidsson
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 #ifndef AVCODEC_RND_AVG_H
23 #define AVCODEC_RND_AVG_H
24 
25 #include <stddef.h>
26 #include <stdint.h>
27 
28 #define BYTE_VEC32(c) ((c) * 0x01010101UL)
29 #define BYTE_VEC64(c) ((c) * 0x0001000100010001UL)
30 
31 static inline uint32_t rnd_avg32(uint32_t a, uint32_t b)
32 {
33  return (a | b) - (((a ^ b) & ~BYTE_VEC32(0x01)) >> 1);
34 }
35 
36 static inline uint32_t no_rnd_avg32(uint32_t a, uint32_t b)
37 {
38  return (a & b) + (((a ^ b) & ~BYTE_VEC32(0x01)) >> 1);
39 }
40 
41 static inline uint64_t rnd_avg64(uint64_t a, uint64_t b)
42 {
43  return (a | b) - (((a ^ b) & ~BYTE_VEC64(0x01)) >> 1);
44 }
45 
46 static inline uint64_t no_rnd_avg64(uint64_t a, uint64_t b)
47 {
48  return (a & b) + (((a ^ b) & ~BYTE_VEC64(0x01)) >> 1);
49 }
50 
51 #endif /* AVCODEC_RND_AVG_H */
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
Definition: undefined.txt:36
static uint64_t no_rnd_avg64(uint64_t a, uint64_t b)
Definition: rnd_avg.h:46
#define b
Definition: input.c:41
static uint32_t no_rnd_avg32(uint32_t a, uint32_t b)
Definition: rnd_avg.h:36
#define BYTE_VEC32(c)
Definition: rnd_avg.h:28
static uint32_t rnd_avg32(uint32_t a, uint32_t b)
Definition: rnd_avg.h:31
#define BYTE_VEC64(c)
Definition: rnd_avg.h:29
static uint64_t rnd_avg64(uint64_t a, uint64_t b)
Definition: rnd_avg.h:41