FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
intmath.h
Go to the documentation of this file.
1 /*
2  * Copyright (c) 2010 Mans Rullgard <mans@mansr.com>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #ifndef AVUTIL_INTMATH_H
22 #define AVUTIL_INTMATH_H
23 
24 #include <stdint.h>
25 
26 #include "config.h"
27 #include "attributes.h"
28 
29 #if ARCH_ARM
30 # include "arm/intmath.h"
31 #endif
32 
33 /**
34  * @addtogroup lavu_internal
35  * @{
36  */
37 
38 #if ARCH_ARM
39 # include "arm/intmath.h"
40 #endif
41 
42 #if HAVE_FAST_CLZ && AV_GCC_VERSION_AT_LEAST(3,4)
43 
44 #ifndef ff_log2
45 # define ff_log2(x) (31 - __builtin_clz((x)|1))
46 # ifndef ff_log2_16bit
47 # define ff_log2_16bit av_log2
48 # endif
49 #endif /* ff_log2 */
50 
51 #endif /* AV_GCC_VERSION_AT_LEAST(3,4) */
52 
53 extern const uint8_t ff_log2_tab[256];
54 
55 #ifndef ff_log2
56 #define ff_log2 ff_log2_c
57 static av_always_inline av_const int ff_log2_c(unsigned int v)
58 {
59  int n = 0;
60  if (v & 0xffff0000) {
61  v >>= 16;
62  n += 16;
63  }
64  if (v & 0xff00) {
65  v >>= 8;
66  n += 8;
67  }
68  n += ff_log2_tab[v];
69 
70  return n;
71 }
72 #endif
73 
74 #ifndef ff_log2_16bit
75 #define ff_log2_16bit ff_log2_16bit_c
76 static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)
77 {
78  int n = 0;
79  if (v & 0xff00) {
80  v >>= 8;
81  n += 8;
82  }
83  n += ff_log2_tab[v];
84 
85  return n;
86 }
87 #endif
88 
89 #define av_log2 ff_log2
90 #define av_log2_16bit ff_log2_16bit
91 
92 /**
93  * @}
94  */
95 
96 /**
97  * @addtogroup lavu_math
98  * @{
99  */
100 
101 #if HAVE_FAST_CLZ && AV_GCC_VERSION_AT_LEAST(3,4)
102 #ifndef ff_ctz
103 #define ff_ctz(v) __builtin_ctz(v)
104 #endif
105 #endif
106 
107 #ifndef ff_ctz
108 #define ff_ctz ff_ctz_c
110 {
111  int c;
112 
113  if (v & 0x1)
114  return 0;
115 
116  c = 1;
117  if (!(v & 0xffff)) {
118  v >>= 16;
119  c += 16;
120  }
121  if (!(v & 0xff)) {
122  v >>= 8;
123  c += 8;
124  }
125  if (!(v & 0xf)) {
126  v >>= 4;
127  c += 4;
128  }
129  if (!(v & 0x3)) {
130  v >>= 2;
131  c += 2;
132  }
133  c -= v & 0x1;
134 
135  return c;
136 }
137 #endif
138 
139 /**
140  * Trailing zero bit count.
141  *
142  * @param v input value. If v is 0, the result is undefined.
143  * @return the number of trailing 0-bits
144  */
145 int av_ctz(int v);
146 
147 /**
148  * @}
149  */
150 #endif /* AVUTIL_INTMATH_H */