mathematics.h 5.1 KB

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  1. /*
  2. * copyright (c) 2005-2012 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. #include "intfloat.h"
  27. #ifndef M_E
  28. #define M_E 2.7182818284590452354 /* e */
  29. #endif
  30. #ifndef M_LN2
  31. #define M_LN2 0.69314718055994530942 /* log_e 2 */
  32. #endif
  33. #ifndef M_LN10
  34. #define M_LN10 2.30258509299404568402 /* log_e 10 */
  35. #endif
  36. #ifndef M_LOG2_10
  37. #define M_LOG2_10 3.32192809488736234787 /* log_2 10 */
  38. #endif
  39. #ifndef M_PHI
  40. #define M_PHI 1.61803398874989484820 /* phi / golden ratio */
  41. #endif
  42. #ifndef M_PI
  43. #define M_PI 3.14159265358979323846 /* pi */
  44. #endif
  45. #ifndef M_PI_2
  46. #define M_PI_2 1.57079632679489661923 /* pi/2 */
  47. #endif
  48. #ifndef M_SQRT1_2
  49. #define M_SQRT1_2 0.70710678118654752440 /* 1/sqrt(2) */
  50. #endif
  51. #ifndef M_SQRT2
  52. #define M_SQRT2 1.41421356237309504880 /* sqrt(2) */
  53. #endif
  54. #ifndef NAN
  55. #define NAN av_int2float(0x7fc00000)
  56. #endif
  57. #ifndef INFINITY
  58. #define INFINITY av_int2float(0x7f800000)
  59. #endif
  60. /**
  61. * @addtogroup lavu_math
  62. * @{
  63. */
  64. enum AVRounding {
  65. AV_ROUND_ZERO = 0, ///< Round toward zero.
  66. AV_ROUND_INF = 1, ///< Round away from zero.
  67. AV_ROUND_DOWN = 2, ///< Round toward -infinity.
  68. AV_ROUND_UP = 3, ///< Round toward +infinity.
  69. AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero.
  70. AV_ROUND_PASS_MINMAX = 8192, ///< Flag to pass INT64_MIN/MAX through instead of rescaling, this avoids special cases for AV_NOPTS_VALUE
  71. };
  72. /**
  73. * Return the greatest common divisor of a and b.
  74. * If both a and b are 0 or either or both are <0 then behavior is
  75. * undefined.
  76. */
  77. int64_t av_const av_gcd(int64_t a, int64_t b);
  78. /**
  79. * Rescale a 64-bit integer with rounding to nearest.
  80. * A simple a*b/c isn't possible as it can overflow.
  81. */
  82. int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const;
  83. /**
  84. * Rescale a 64-bit integer with specified rounding.
  85. * A simple a*b/c isn't possible as it can overflow.
  86. *
  87. * @return rescaled value a, or if AV_ROUND_PASS_MINMAX is set and a is
  88. * INT64_MIN or INT64_MAX then a is passed through unchanged.
  89. */
  90. int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding) av_const;
  91. /**
  92. * Rescale a 64-bit integer by 2 rational numbers.
  93. */
  94. int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const;
  95. /**
  96. * Rescale a 64-bit integer by 2 rational numbers with specified rounding.
  97. *
  98. * @return rescaled value a, or if AV_ROUND_PASS_MINMAX is set and a is
  99. * INT64_MIN or INT64_MAX then a is passed through unchanged.
  100. */
  101. int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq,
  102. enum AVRounding) av_const;
  103. /**
  104. * Compare 2 timestamps each in its own timebases.
  105. * The result of the function is undefined if one of the timestamps
  106. * is outside the int64_t range when represented in the others timebase.
  107. * @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
  108. */
  109. int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b);
  110. /**
  111. * Compare 2 integers modulo mod.
  112. * That is we compare integers a and b for which only the least
  113. * significant log2(mod) bits are known.
  114. *
  115. * @param mod must be a power of 2
  116. * @return a negative value if a is smaller than b
  117. * a positive value if a is greater than b
  118. * 0 if a equals b
  119. */
  120. int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod);
  121. /**
  122. * Rescale a timestamp while preserving known durations.
  123. *
  124. * @param in_ts Input timestamp
  125. * @param in_tb Input timebase
  126. * @param fs_tb Duration and *last timebase
  127. * @param duration duration till the next call
  128. * @param out_tb Output timebase
  129. */
  130. int64_t av_rescale_delta(AVRational in_tb, int64_t in_ts, AVRational fs_tb, int duration, int64_t *last, AVRational out_tb);
  131. /**
  132. * Add a value to a timestamp.
  133. *
  134. * This function guarantees that when the same value is repeatly added that
  135. * no accumulation of rounding errors occurs.
  136. *
  137. * @param ts Input timestamp
  138. * @param ts_tb Input timestamp timebase
  139. * @param inc value to add to ts
  140. * @param inc_tb inc timebase
  141. */
  142. int64_t av_add_stable(AVRational ts_tb, int64_t ts, AVRational inc_tb, int64_t inc);
  143. /**
  144. * @}
  145. */
  146. #endif /* AVUTIL_MATHEMATICS_H */