FFmpeg
intmath.h
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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 #if ARCH_X86
33 # include "x86/intmath.h"
34 #endif
35 
36 #if HAVE_FAST_CLZ
37 #if AV_GCC_VERSION_AT_LEAST(3,4)
38 #ifndef ff_log2
39 # define ff_log2(x) (31 - __builtin_clz((x)|1))
40 # ifndef ff_log2_16bit
41 # define ff_log2_16bit av_log2
42 # endif
43 #endif /* ff_log2 */
44 #endif /* AV_GCC_VERSION_AT_LEAST(3,4) */
45 #endif
46 
47 extern const uint8_t ff_log2_tab[256];
48 
49 #ifndef ff_log2
50 #define ff_log2 ff_log2_c
51 static av_always_inline av_const int ff_log2_c(unsigned int v)
52 {
53  int n = 0;
54  if (v & 0xffff0000) {
55  v >>= 16;
56  n += 16;
57  }
58  if (v & 0xff00) {
59  v >>= 8;
60  n += 8;
61  }
62  n += ff_log2_tab[v];
63 
64  return n;
65 }
66 #endif
67 
68 #ifndef ff_log2_16bit
69 #define ff_log2_16bit ff_log2_16bit_c
70 static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)
71 {
72  int n = 0;
73  if (v & 0xff00) {
74  v >>= 8;
75  n += 8;
76  }
77  n += ff_log2_tab[v];
78 
79  return n;
80 }
81 #endif
82 
83 #define av_log2 ff_log2
84 #define av_log2_16bit ff_log2_16bit
85 
86 /**
87  * @addtogroup lavu_math
88  * @{
89  */
90 
91 #if HAVE_FAST_CLZ
92 #if AV_GCC_VERSION_AT_LEAST(3,4)
93 #ifndef ff_ctz
94 #define ff_ctz(v) __builtin_ctz(v)
95 #endif
96 #ifndef ff_ctzll
97 #define ff_ctzll(v) __builtin_ctzll(v)
98 #endif
99 #ifndef ff_clz
100 #define ff_clz(v) __builtin_clz(v)
101 #endif
102 #endif
103 #endif
104 
105 #ifndef ff_ctz
106 #define ff_ctz ff_ctz_c
107 /**
108  * Trailing zero bit count.
109  *
110  * @param v input value. If v is 0, the result is undefined.
111  * @return the number of trailing 0-bits
112  */
113 /* We use the De-Bruijn method outlined in:
114  * http://supertech.csail.mit.edu/papers/debruijn.pdf. */
116 {
117  static const uint8_t debruijn_ctz32[32] = {
118  0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8,
119  31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9
120  };
121  return debruijn_ctz32[(uint32_t)((v & -v) * 0x077CB531U) >> 27];
122 }
123 #endif
124 
125 #ifndef ff_ctzll
126 #define ff_ctzll ff_ctzll_c
127 /* We use the De-Bruijn method outlined in:
128  * http://supertech.csail.mit.edu/papers/debruijn.pdf. */
129 static av_always_inline av_const int ff_ctzll_c(long long v)
130 {
131  static const uint8_t debruijn_ctz64[64] = {
132  0, 1, 2, 53, 3, 7, 54, 27, 4, 38, 41, 8, 34, 55, 48, 28,
133  62, 5, 39, 46, 44, 42, 22, 9, 24, 35, 59, 56, 49, 18, 29, 11,
134  63, 52, 6, 26, 37, 40, 33, 47, 61, 45, 43, 21, 23, 58, 17, 10,
135  51, 25, 36, 32, 60, 20, 57, 16, 50, 31, 19, 15, 30, 14, 13, 12
136  };
137  return debruijn_ctz64[(uint64_t)((v & -v) * 0x022FDD63CC95386DU) >> 58];
138 }
139 #endif
140 
141 #ifndef ff_clz
142 #define ff_clz ff_clz_c
143 static av_always_inline av_const unsigned ff_clz_c(unsigned x)
144 {
145  unsigned i = sizeof(x) * 8;
146 
147  while (x) {
148  x >>= 1;
149  i--;
150  }
151 
152  return i;
153 }
154 #endif
155 
156 #if AV_GCC_VERSION_AT_LEAST(3,4)
157 #ifndef av_parity
158 #define av_parity __builtin_parity
159 #endif
160 #endif
161 
162 /**
163  * @}
164  */
165 #endif /* AVUTIL_INTMATH_H */
#define av_const
Definition: attributes.h:76
Macro definitions for various function/variable attributes.
static av_always_inline av_const unsigned ff_clz_c(unsigned x)
Definition: intmath.h:143
uint8_t
static av_always_inline av_const int ff_ctz_c(int v)
Trailing zero bit count.
Definition: intmath.h:115
#define U(x)
Definition: vp56_arith.h:37
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
int n
Definition: avisynth_c.h:760
const uint8_t ff_log2_tab[256]
Definition: log2_tab.c:23
static av_always_inline av_const int ff_ctzll_c(long long v)
Definition: intmath.h:129
#define av_always_inline
Definition: attributes.h:39
static av_always_inline av_const int ff_log2_c(unsigned int v)
Definition: intmath.h:51
static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)
Definition: intmath.h:70