ffmpeg/libavutil/mathematics.h

   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
  21 #ifndef AVUTIL_MATHEMATICS_H
  22 #define AVUTIL_MATHEMATICS_H
  23
  24 #include <stdint.h>
  25 #include <math.h>
  26 #include "attributes.h"
  27 #include "rational.h"
  28 #include "intfloat.h"
  29
  30 #ifndef M_E
  31 #define M_E            2.7182818284590452354   /* e */
  32 #endif
  33 #ifndef M_LN2
  34 #define M_LN2          0.69314718055994530942  /* log_e 2 */
  35 #endif
  36 #ifndef M_LN10
  37 #define M_LN10         2.30258509299404568402  /* log_e 10 */
  38 #endif
  39 #ifndef M_LOG2_10
  40 #define M_LOG2_10      3.32192809488736234787  /* log_2 10 */
  41 #endif
  42 #ifndef M_PHI
  43 #define M_PHI          1.61803398874989484820   /* phi / golden ratio */
  44 #endif
  45 #ifndef M_PI
  46 #define M_PI           3.14159265358979323846  /* pi */
  47 #endif
  48 #ifndef M_PI_2
  49 #define M_PI_2         1.57079632679489661923  /* pi/2 */
  50 #endif
  51 #ifndef M_SQRT1_2
  52 #define M_SQRT1_2      0.70710678118654752440  /* 1/sqrt(2) */
  53 #endif
  54 #ifndef M_SQRT2
  55 #define M_SQRT2        1.41421356237309504880  /* sqrt(2) */
  56 #endif
  57 #ifndef NAN
  58 #define NAN            av_int2float(0x7fc00000)
  59 #endif
  60 #ifndef INFINITY
  61 #define INFINITY       av_int2float(0x7f800000)
  62 #endif
  63
  64 /**
  65  * @addtogroup lavu_math
  66  * @{
  67  */
  68
  69
  70 enum AVRounding {
  71     AV_ROUND_ZERO     = 0, ///< Round toward zero.
  72     AV_ROUND_INF      = 1, ///< Round away from zero.
  73     AV_ROUND_DOWN     = 2, ///< Round toward -infinity.
  74     AV_ROUND_UP       = 3, ///< Round toward +infinity.
  75     AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero.
  76     AV_ROUND_PASS_MINMAX = 8192, ///< Flag to pass INT64_MIN/MAX through instead of rescaling, this avoids special cases for AV_NOPTS_VALUE
  77 };
  78
  79 /**
  80  * Return the greatest common divisor of a and b.
  81  * If both a and b are 0 or either or both are <0 then behavior is
  82  * undefined.
  83  */
  84 int64_t av_const av_gcd(int64_t a, int64_t b);
  85
  86 /**
  87  * Rescale a 64-bit integer with rounding to nearest.
  88  * A simple a*b/c isn't possible as it can overflow.
  89  */
  90 int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const;
  91
  92 /**
  93  * Rescale a 64-bit integer with specified rounding.
  94  * A simple a*b/c isn't possible as it can overflow.
  95  *
  96  * @return rescaled value a, or if AV_ROUND_PASS_MINMAX is set and a is
  97  *         INT64_MIN or INT64_MAX then a is passed through unchanged.
  98  */
  99 int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding) av_const;
 100
 101 /**
 102  * Rescale a 64-bit integer by 2 rational numbers.
 103  */
 104 int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const;
 105
 106 /**
 107  * Rescale a 64-bit integer by 2 rational numbers with specified rounding.
 108  *
 109  * @return rescaled value a, or if AV_ROUND_PASS_MINMAX is set and a is
 110  *         INT64_MIN or INT64_MAX then a is passed through unchanged.
 111  */
 112 int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq,
 113                          enum AVRounding) av_const;
 114
 115 /**
 116  * Compare 2 timestamps each in its own timebases.
 117  * The result of the function is undefined if one of the timestamps
 118  * is outside the int64_t range when represented in the others timebase.
 119  * @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
 120  */
 121 int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b);
 122
 123 /**
 124  * Compare 2 integers modulo mod.
 125  * That is we compare integers a and b for which only the least
 126  * significant log2(mod) bits are known.
 127  *
 128  * @param mod must be a power of 2
 129  * @return a negative value if a is smaller than b
 130  *         a positive value if a is greater than b
 131  *         0                if a equals          b
 132  */
 133 int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod);
 134
 135 /**
 136  * Rescale a timestamp while preserving known durations.
 137  *
 138  * @param in_ts Input timestamp
 139  * @param in_tb Input timebase
 140  * @param fs_tb Duration and *last timebase
 141  * @param duration duration till the next call
 142  * @param out_tb Output timebase
 143  */
 144 int64_t av_rescale_delta(AVRational in_tb, int64_t in_ts,  AVRational fs_tb, int duration, int64_t *last, AVRational out_tb);
 145
 146 /**
 147  * Add a value to a timestamp.
 148  *
 149  * This function guarantees that when the same value is repeatly added that
 150  * no accumulation of rounding errors occurs.
 151  *
 152  * @param ts Input timestamp
 153  * @param ts_tb Input timestamp timebase
 154  * @param inc value to add to ts
 155  * @param inc_tb inc timebase
 156  */
 157 int64_t av_add_stable(AVRational ts_tb, int64_t ts, AVRational inc_tb, int64_t inc);
 158
 159
 160     /**
 161  * @}
 162  */
 163
 164 #endif /* AVUTIL_MATHEMATICS_H */