mathematics.h 3.33 KB
Newer Older
1 2 3
/*
 * copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
 *
4
 * This file is part of Libav.
5
 *
6
 * Libav is free software; you can redistribute it and/or
7 8
 * modify it under the terms of the GNU Lesser General Public
 * 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 13 14 15 16
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * 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 19 20
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

21 22
#ifndef AVUTIL_MATHEMATICS_H
#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 34 35
#ifndef M_PHI
#define M_PHI          1.61803398874989484820   /* phi / golden ratio */
#endif
36
#ifndef NAN
37
#define NAN            av_int2float(0x7fc00000)
38 39
#endif
#ifndef INFINITY
40
#define INFINITY       av_int2float(0x7f800000)
41
#endif
42

43 44 45 46 47 48
/**
 * @addtogroup lavu_math
 * @{
 */


49
enum AVRounding {
50 51 52 53 54
    AV_ROUND_ZERO     = 0, ///< Round toward zero.
    AV_ROUND_INF      = 1, ///< Round away from zero.
    AV_ROUND_DOWN     = 2, ///< Round toward -infinity.
    AV_ROUND_UP       = 3, ///< Round toward +infinity.
    AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero.
55 56
};

Michael Niedermayer's avatar
Michael Niedermayer committed
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
Michael Niedermayer's avatar
Michael Niedermayer committed
60 61
 * undefined.
 */
62 63
int64_t av_const av_gcd(int64_t a, int64_t b);

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 83 84 85 86
/**
 * Rescale a 64-bit integer by 2 rational numbers with specified rounding.
 */
int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq,
                         enum AVRounding) av_const;

Michael Niedermayer's avatar
Michael Niedermayer committed
87
/**
88
 * Compare 2 timestamps each in its own timebases.
Michael Niedermayer's avatar
Michael Niedermayer committed
89 90
 * The result of the function is undefined if one of the timestamps
 * 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
Michael Niedermayer's avatar
Michael Niedermayer committed
92 93 94
 */
int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b);

95
/**
96
 * Compare 2 integers modulo mod.
97 98 99
 * That is we compare integers a and b for which only the least
 * significant log2(mod) bits are known.
 *
100
 * @param mod must be a power of 2
101 102 103
 * @return a negative value if a is smaller than b
 *         a positive value if a is greater than b
 *         0                if a equals          b
104 105
 */
int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod);
Michael Niedermayer's avatar
Michael Niedermayer committed
106

107 108 109 110
/**
 * @}
 */

111
#endif /* AVUTIL_MATHEMATICS_H */