libavutil/mathematics.h

   1 /*
   2  * copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
   3  *
   4  * This file is part of Libav.
   5  *
   6  * Libav 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  * Libav 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 Libav; 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_LOG2_10
  31 #define M_LOG2_10      3.32192809488736234787  /* log_2 10 */
  32 #endif
  33 #ifndef M_PHI
  34 #define M_PHI          1.61803398874989484820   /* phi / golden ratio */
  35 #endif
  36 #ifndef NAN
  37 #define NAN            av_int2float(0x7fc00000)
  38 #endif
  39 #ifndef INFINITY
  40 #define INFINITY       av_int2float(0x7f800000)
  41 #endif
  42
  43 /**
  44  * @addtogroup lavu_math
  45  * @{
  46  */
  47
  48
  49 enum AVRounding {
  50     AV_ROUND_ZERO     = 0, ///< Round toward zero.
  51     AV_ROUND_INF      = 1, ///< Round away from zero.
  52     AV_ROUND_DOWN     = 2, ///< Round toward -infinity.
  53     AV_ROUND_UP       = 3, ///< Round toward +infinity.
  54     AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero.
  55 };
  56
  57 /**
  58  * Return the greatest common divisor of a and b.
  59  * If both a and b are 0 or either or both are <0 then behavior is
  60  * undefined.
  61  */
  62 int64_t av_const av_gcd(int64_t a, int64_t b);
  63
  64 /**
  65  * Rescale a 64-bit integer with rounding to nearest.
  66  * A simple a*b/c isn't possible as it can overflow.
  67  */
  68 int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const;
  69
  70 /**
  71  * Rescale a 64-bit integer with specified rounding.
  72  * A simple a*b/c isn't possible as it can overflow.
  73  */
  74 int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding) av_const;
  75
  76 /**
  77  * Rescale a 64-bit integer by 2 rational numbers.
  78  */
  79 int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const;
  80
  81 /**
  82  * Rescale a 64-bit integer by 2 rational numbers with specified rounding.
  83  */
  84 int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq,
  85                          enum AVRounding) av_const;
  86
  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 /**
  96  * Compare 2 integers modulo mod.
  97  * That is we compare integers a and b for which only the least
  98  * significant log2(mod) bits are known.
  99  *
 100  * @param mod must be a power of 2
 101  * @return a negative value if a is smaller than b
 102  *         a positive value if a is greater than b
 103  *         0                if a equals          b
 104  */
 105 int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod);
 106
 107 /**
 108  * @}
 109  */
 110
 111 #endif /* AVUTIL_MATHEMATICS_H */