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 && 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 /**
  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  *
 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 */