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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. #if ARCH_X86
  33. #   include "x86/intmath.h"
  34. #endif
  35.  
  36. #if HAVE_FAST_CLZ
  37. #if defined( __INTEL_COMPILER )
  38. #ifndef ff_log2
  39. #   define ff_log2(x) (_bit_scan_reverse((x)|1))
  40. #   ifndef ff_log2_16bit
  41. #      define ff_log2_16bit av_log2
  42. #   endif
  43. #endif /* ff_log2 */
  44. #elif AV_GCC_VERSION_AT_LEAST(3,4)
  45. #ifndef ff_log2
  46. #   define ff_log2(x) (31 - __builtin_clz((x)|1))
  47. #   ifndef ff_log2_16bit
  48. #      define ff_log2_16bit av_log2
  49. #   endif
  50. #endif /* ff_log2 */
  51. #endif /* AV_GCC_VERSION_AT_LEAST(3,4) */
  52. #endif
  53.  
  54. extern const uint8_t ff_log2_tab[256];
  55.  
  56. #ifndef ff_log2
  57. #define ff_log2 ff_log2_c
  58. #if !defined( _MSC_VER )
  59. static av_always_inline av_const int ff_log2_c(unsigned int v)
  60. {
  61.     int n = 0;
  62.     if (v & 0xffff0000) {
  63.         v >>= 16;
  64.         n += 16;
  65.     }
  66.     if (v & 0xff00) {
  67.         v >>= 8;
  68.         n += 8;
  69.     }
  70.     n += ff_log2_tab[v];
  71.  
  72.     return n;
  73. }
  74. #else
  75. static av_always_inline av_const int ff_log2_c(unsigned int v)
  76. {
  77.     unsigned long n;
  78.     _BitScanReverse(&n, v|1);
  79.     return n;
  80. }
  81. #define ff_log2_16bit av_log2
  82. #endif
  83. #endif
  84.  
  85. #ifndef ff_log2_16bit
  86. #define ff_log2_16bit ff_log2_16bit_c
  87. static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)
  88. {
  89.     int n = 0;
  90.     if (v & 0xff00) {
  91.         v >>= 8;
  92.         n += 8;
  93.     }
  94.     n += ff_log2_tab[v];
  95.  
  96.     return n;
  97. }
  98. #endif
  99.  
  100. #define av_log2       ff_log2
  101. #define av_log2_16bit ff_log2_16bit
  102.  
  103. /**
  104.  * @addtogroup lavu_math
  105.  * @{
  106.  */
  107.  
  108. #if HAVE_FAST_CLZ
  109. #if defined( __INTEL_COMPILER )
  110. #ifndef ff_ctz
  111. #define ff_ctz(v) _bit_scan_forward(v)
  112. #endif
  113. #elif AV_GCC_VERSION_AT_LEAST(3,4)
  114. #ifndef ff_ctz
  115. #define ff_ctz(v) __builtin_ctz(v)
  116. #endif
  117. #endif
  118. #endif
  119.  
  120. #ifndef ff_ctz
  121. #define ff_ctz ff_ctz_c
  122. #if !defined( _MSC_VER )
  123. static av_always_inline av_const int ff_ctz_c(int v)
  124. {
  125.     int c;
  126.  
  127.     if (v & 0x1)
  128.         return 0;
  129.  
  130.     c = 1;
  131.     if (!(v & 0xffff)) {
  132.         v >>= 16;
  133.         c += 16;
  134.     }
  135.     if (!(v & 0xff)) {
  136.         v >>= 8;
  137.         c += 8;
  138.     }
  139.     if (!(v & 0xf)) {
  140.         v >>= 4;
  141.         c += 4;
  142.     }
  143.     if (!(v & 0x3)) {
  144.         v >>= 2;
  145.         c += 2;
  146.     }
  147.     c -= v & 0x1;
  148.  
  149.     return c;
  150. }
  151. #else
  152. static av_always_inline av_const int ff_ctz_c( int v )
  153. {
  154.     unsigned long c;
  155.     _BitScanForward(&c, v);
  156.     return c;
  157. }
  158. #endif
  159. #endif
  160.  
  161. /**
  162.  * Trailing zero bit count.
  163.  *
  164.  * @param v  input value. If v is 0, the result is undefined.
  165.  * @return   the number of trailing 0-bits
  166.  */
  167. int av_ctz(int v);
  168.  
  169. /**
  170.  * @}
  171.  */
  172. #endif /* AVUTIL_INTMATH_H */
  173.