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