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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. #endif
  32.  
  33. /**
  34.  * @addtogroup lavu_internal
  35.  * @{
  36.  */
  37.  
  38. #if   ARCH_ARM
  39. #   include "arm/intmath.h"
  40. #endif
  41.  
  42. #if HAVE_FAST_CLZ && AV_GCC_VERSION_AT_LEAST(3,4)
  43.  
  44. #ifndef ff_log2
  45. #   define ff_log2(x) (31 - __builtin_clz((x)|1))
  46. #   ifndef ff_log2_16bit
  47. #      define ff_log2_16bit av_log2
  48. #   endif
  49. #endif /* ff_log2 */
  50.  
  51. #endif /* AV_GCC_VERSION_AT_LEAST(3,4) */
  52.  
  53. extern const uint8_t ff_log2_tab[256];
  54.  
  55. #ifndef ff_log2
  56. #define ff_log2 ff_log2_c
  57. static av_always_inline av_const int ff_log2_c(unsigned int v)
  58. {
  59.     int n = 0;
  60.     if (v & 0xffff0000) {
  61.         v >>= 16;
  62.         n += 16;
  63.     }
  64.     if (v & 0xff00) {
  65.         v >>= 8;
  66.         n += 8;
  67.     }
  68.     n += ff_log2_tab[v];
  69.  
  70.     return n;
  71. }
  72. #endif
  73.  
  74. #ifndef ff_log2_16bit
  75. #define ff_log2_16bit ff_log2_16bit_c
  76. static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)
  77. {
  78.     int n = 0;
  79.     if (v & 0xff00) {
  80.         v >>= 8;
  81.         n += 8;
  82.     }
  83.     n += ff_log2_tab[v];
  84.  
  85.     return n;
  86. }
  87. #endif
  88.  
  89. #define av_log2       ff_log2
  90. #define av_log2_16bit ff_log2_16bit
  91.  
  92. /**
  93.  * @}
  94.  */
  95.  
  96. /**
  97.  * @addtogroup lavu_math
  98.  * @{
  99.  */
  100.  
  101. #if HAVE_FAST_CLZ && AV_GCC_VERSION_AT_LEAST(3,4)
  102. #ifndef ff_ctz
  103. #define ff_ctz(v) __builtin_ctz(v)
  104. #endif
  105. #endif
  106.  
  107. #ifndef ff_ctz
  108. #define ff_ctz ff_ctz_c
  109. static av_always_inline av_const int ff_ctz_c(int v)
  110. {
  111.     int c;
  112.  
  113.     if (v & 0x1)
  114.         return 0;
  115.  
  116.     c = 1;
  117.     if (!(v & 0xffff)) {
  118.         v >>= 16;
  119.         c += 16;
  120.     }
  121.     if (!(v & 0xff)) {
  122.         v >>= 8;
  123.         c += 8;
  124.     }
  125.     if (!(v & 0xf)) {
  126.         v >>= 4;
  127.         c += 4;
  128.     }
  129.     if (!(v & 0x3)) {
  130.         v >>= 2;
  131.         c += 2;
  132.     }
  133.     c -= v & 0x1;
  134.  
  135.     return c;
  136. }
  137. #endif
  138.  
  139. /**
  140.  * Trailing zero bit count.
  141.  *
  142.  * @param v  input value. If v is 0, the result is undefined.
  143.  * @return   the number of trailing 0-bits
  144.  */
  145. int av_ctz(int v);
  146.  
  147. /**
  148.  * @}
  149.  */
  150. #endif /* AVUTIL_INTMATH_H */
  151.