ffmpeg/libavutil/intmath.h

   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 HAVE_FAST_CLZ
  39 #if AV_GCC_VERSION_AT_LEAST(3,4)
  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 #elif defined( __INTEL_COMPILER )
  47 #ifndef ff_log2
  48 #   define ff_log2(x) (_bit_scan_reverse(x|1))
  49 #   ifndef ff_log2_16bit
  50 #      define ff_log2_16bit av_log2
  51 #   endif
  52 #endif /* ff_log2 */
  53 #endif
  54 #endif /* AV_GCC_VERSION_AT_LEAST(3,4) */
  55
  56 extern const uint8_t ff_log2_tab[256];
  57
  58 #ifndef ff_log2
  59 #define ff_log2 ff_log2_c
  60 #if !defined( _MSC_VER )
  61 static av_always_inline av_const int ff_log2_c(unsigned int v)
  62 {
  63     int n = 0;
  64     if (v & 0xffff0000) {
  65         v >>= 16;
  66         n += 16;
  67     }
  68     if (v & 0xff00) {
  69         v >>= 8;
  70         n += 8;
  71     }
  72     n += ff_log2_tab[v];
  73
  74     return n;
  75 }
  76 #else
  77 static av_always_inline av_const int ff_log2_c(unsigned int v)
  78 {
  79     unsigned long n;
  80     _BitScanReverse(&n, v|1);
  81     return n;
  82 }
  83 #define ff_log2_16bit av_log2
  84 #endif
  85 #endif
  86
  87 #ifndef ff_log2_16bit
  88 #define ff_log2_16bit ff_log2_16bit_c
  89 static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)
  90 {
  91     int n = 0;
  92     if (v & 0xff00) {
  93         v >>= 8;
  94         n += 8;
  95     }
  96     n += ff_log2_tab[v];
  97
  98     return n;
  99 }
 100 #endif
 101
 102 #define av_log2       ff_log2
 103 #define av_log2_16bit ff_log2_16bit
 104
 105 /**
 106  * @}
 107  */
 108
 109 /**
 110  * @addtogroup lavu_math
 111  * @{
 112  */
 113
 114 #if HAVE_FAST_CLZ
 115 #if AV_GCC_VERSION_AT_LEAST(3,4)
 116 #ifndef ff_ctz
 117 #define ff_ctz(v) __builtin_ctz(v)
 118 #endif
 119 #elif defined( __INTEL_COMPILER )
 120 #ifndef ff_ctz
 121 #define ff_ctz(v) _bit_scan_forward(v)
 122 #endif
 123 #endif
 124 #endif
 125
 126 #ifndef ff_ctz
 127 #define ff_ctz ff_ctz_c
 128 #if !defined( _MSC_VER )
 129 static av_always_inline av_const int ff_ctz_c(int v)
 130 {
 131     int c;
 132
 133     if (v & 0x1)
 134         return 0;
 135
 136     c = 1;
 137     if (!(v & 0xffff)) {
 138         v >>= 16;
 139         c += 16;
 140     }
 141     if (!(v & 0xff)) {
 142         v >>= 8;
 143         c += 8;
 144     }
 145     if (!(v & 0xf)) {
 146         v >>= 4;
 147         c += 4;
 148     }
 149     if (!(v & 0x3)) {
 150         v >>= 2;
 151         c += 2;
 152     }
 153     c -= v & 0x1;
 154
 155     return c;
 156 }
 157 #else
 158 static av_always_inline av_const int ff_ctz_c( int v )
 159 {
 160     unsigned long c;
 161     _BitScanForward(&c, v);
 162     return c;
 163 }
 164 #endif
 165 #endif
 166
 167 /**
 168  * Trailing zero bit count.
 169  *
 170  * @param v  input value. If v is 0, the result is undefined.
 171  * @return   the number of trailing 0-bits
 172  */
 173 int av_ctz(int v);
 174
 175 /**
 176  * @}
 177  */
 178 #endif /* AVUTIL_INTMATH_H */