1 /* 2 * Copyright (c) 2010 Mans Rullgard <mans@mansr.com> 3 * 4 * This file is part of Libav. 5 * 6 * Libav 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 * Libav 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 Libav; 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 HAVE_FAST_CLZ && AV_GCC_VERSION_AT_LEAST(3,4) 39 40 #ifndef ff_log2 41 # define ff_log2(x) (31 - __builtin_clz((x)|1)) 42 # ifndef ff_log2_16bit 43 # define ff_log2_16bit av_log2 44 # endif 45 #endif /* ff_log2 */ 46 47 #endif /* AV_GCC_VERSION_AT_LEAST(3,4) */ 48 49 extern const uint8_t ff_log2_tab[256]; 50 51 #ifndef ff_log2 52 #define ff_log2 ff_log2_c 53 static av_always_inline av_const int ff_log2_c(unsigned int v) 54 { 55 int n = 0; 56 if (v & 0xffff0000) { 57 v >>= 16; 58 n += 16; 59 } 60 if (v & 0xff00) { 61 v >>= 8; 62 n += 8; 63 } 64 n += ff_log2_tab[v]; 65 66 return n; 67 } 68 #endif 69 70 #ifndef ff_log2_16bit 71 #define ff_log2_16bit ff_log2_16bit_c 72 static av_always_inline av_const int ff_log2_16bit_c(unsigned int v) 73 { 74 int n = 0; 75 if (v & 0xff00) { 76 v >>= 8; 77 n += 8; 78 } 79 n += ff_log2_tab[v]; 80 81 return n; 82 } 83 #endif 84 85 #define av_log2 ff_log2 86 #define av_log2_16bit ff_log2_16bit 87 88 /** 89 * @} 90 */ 91 92 /** av_clip_c(int a,int amin,int amax)93 * @addtogroup lavu_math 94 * @{ 95 */ 96 97 #if HAVE_FAST_CLZ && AV_GCC_VERSION_AT_LEAST(3,4) 98 #ifndef ff_ctz 99 #define ff_ctz(v) __builtin_ctz(v) 100 #endif 101 #endif 102 103 #ifndef ff_ctz 104 #define ff_ctz ff_ctz_c 105 static av_always_inline av_const int ff_ctz_c(int v) 106 { 107 int c; 108 109 if (v & 0x1) 110 return 0; 111 112 c = 1; 113 if (!(v & 0xffff)) { 114 v >>= 16; 115 c += 16; 116 } 117 if (!(v & 0xff)) { 118 v >>= 8; 119 c += 8; 120 } 121 if (!(v & 0xf)) { 122 v >>= 4; 123 c += 4; 124 } 125 if (!(v & 0x3)) { 126 v >>= 2; 127 c += 2; 128 } 129 c -= v & 0x1; 130 131 return c; 132 } 133 #endif 134 135 /** 136 * Trailing zero bit count. 137 * av_clip_int16_c(int a)138 * @param v input value. If v is 0, the result is undefined. 139 * @return the number of trailing 0-bits 140 */ 141 int av_ctz(int v); 142 143 /** 144 * @} 145 */ 146 #endif /* AVUTIL_INTMATH_H */ 147