mathematics.h 3.6 KB

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  1. /*
  2. * copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
  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. #ifndef AVUTIL_MATHEMATICS_H
  21. #define AVUTIL_MATHEMATICS_H
  22. #include <stdint.h>
  23. #include <math.h>
  24. #include "attributes.h"
  25. #include "rational.h"
  26. #ifndef M_E
  27. #define M_E 2.7182818284590452354 /* e */
  28. #endif
  29. #ifndef M_LN2
  30. #define M_LN2 0.69314718055994530942 /* log_e 2 */
  31. #endif
  32. #ifndef M_LN10
  33. #define M_LN10 2.30258509299404568402 /* log_e 10 */
  34. #endif
  35. #ifndef M_LOG2_10
  36. #define M_LOG2_10 3.32192809488736234787 /* log_2 10 */
  37. #endif
  38. #ifndef M_PHI
  39. #define M_PHI 1.61803398874989484820 /* phi / golden ratio */
  40. #endif
  41. #ifndef M_PI
  42. #define M_PI 3.14159265358979323846 /* pi */
  43. #endif
  44. #ifndef M_SQRT1_2
  45. #define M_SQRT1_2 0.70710678118654752440 /* 1/sqrt(2) */
  46. #endif
  47. #ifndef M_SQRT2
  48. #define M_SQRT2 1.41421356237309504880 /* sqrt(2) */
  49. #endif
  50. #ifndef NAN
  51. #define NAN (0.0/0.0)
  52. #endif
  53. #ifndef INFINITY
  54. #define INFINITY (1.0/0.0)
  55. #endif
  56. /**
  57. * @addtogroup lavu_math
  58. * @{
  59. */
  60. enum AVRounding {
  61. AV_ROUND_ZERO = 0, ///< Round toward zero.
  62. AV_ROUND_INF = 1, ///< Round away from zero.
  63. AV_ROUND_DOWN = 2, ///< Round toward -infinity.
  64. AV_ROUND_UP = 3, ///< Round toward +infinity.
  65. AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero.
  66. };
  67. /**
  68. * Return the greatest common divisor of a and b.
  69. * If both a and b are 0 or either or both are <0 then behavior is
  70. * undefined.
  71. */
  72. int64_t av_const av_gcd(int64_t a, int64_t b);
  73. /**
  74. * Rescale a 64-bit integer with rounding to nearest.
  75. * A simple a*b/c isn't possible as it can overflow.
  76. */
  77. int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const;
  78. /**
  79. * Rescale a 64-bit integer with specified rounding.
  80. * A simple a*b/c isn't possible as it can overflow.
  81. */
  82. int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding) av_const;
  83. /**
  84. * Rescale a 64-bit integer by 2 rational numbers.
  85. */
  86. int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const;
  87. /**
  88. * Compare 2 timestamps each in its own timebases.
  89. * The result of the function is undefined if one of the timestamps
  90. * is outside the int64_t range when represented in the others timebase.
  91. * @return -1 if ts_a is before ts_b, 1 if ts_a is after ts_b or 0 if they represent the same position
  92. */
  93. int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b);
  94. /**
  95. * Compare 2 integers modulo mod.
  96. * That is we compare integers a and b for which only the least
  97. * significant log2(mod) bits are known.
  98. *
  99. * @param mod must be a power of 2
  100. * @return a negative value if a is smaller than b
  101. * a positive value if a is greater than b
  102. * 0 if a equals b
  103. */
  104. int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod);
  105. /**
  106. * @}
  107. */
  108. #endif /* AVUTIL_MATHEMATICS_H */