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"
28
29 #if ARCH_ARM
31 #elif ARCH_RISCV
33 #elif ARCH_X86
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
49
50 #ifndef ff_log2
51 #define ff_log2 ff_log2_c
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 }
64
65 return n;
66 }
67 #endif
68
69 #ifndef ff_log2_16bit
70 #define ff_log2_16bit ff_log2_16bit_c
72 {
73 int n = 0;
74 if (v & 0xff00) {
75 v >>= 8;
76 n += 8;
77 }
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) * 0x077CB531
U) >> 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. */
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) * 0x022FDD63CC95386D
U) >> 58];
139 }
140 #endif
141
142 #ifndef ff_clz
143 #define ff_clz ff_clz_c
145 {
146 unsigned i =
sizeof(x) * 8;
147
148 while (x) {
149 x >>= 1;
151 }
152
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 */