3b783db83284b95ea44d33e58552c9a0d65ec83f
[libav.git] / libavutil / mathematics.h
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
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
29 #ifndef M_E
30 #define M_E 2.7182818284590452354 /* e */
31 #endif
32 #ifndef M_LN2
33 #define M_LN2 0.69314718055994530942 /* log_e 2 */
34 #endif
35 #ifndef M_LN10
36 #define M_LN10 2.30258509299404568402 /* log_e 10 */
37 #endif
38 #ifndef M_LOG2_10
39 #define M_LOG2_10 3.32192809488736234787 /* log_2 10 */
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 NAN
48 #define NAN (0.0/0.0)
49 #endif
50 #ifndef INFINITY
51 #define INFINITY (1.0/0.0)
52 #endif
53
54 enum AVRounding {
55 AV_ROUND_ZERO = 0, ///< Round toward zero.
56 AV_ROUND_INF = 1, ///< Round away from zero.
57 AV_ROUND_DOWN = 2, ///< Round toward -infinity.
58 AV_ROUND_UP = 3, ///< Round toward +infinity.
59 AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero.
60 };
61
62 /**
63 * Returns the greatest common divisor of a and b.
64 * If both a and b are 0 or either or both are <0 then behavior is
65 * undefined.
66 */
67 int64_t av_const av_gcd(int64_t a, int64_t b);
68
69 /**
70 * Rescales a 64-bit integer with rounding to nearest.
71 * A simple a*b/c isn't possible as it can overflow.
72 */
73 int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const;
74
75 /**
76 * Rescales a 64-bit integer with specified rounding.
77 * A simple a*b/c isn't possible as it can overflow.
78 */
79 int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding) av_const;
80
81 /**
82 * Rescales a 64-bit integer by 2 rational numbers.
83 */
84 int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const;
85
86 /**
87 * Compares 2 timestamps each in its own timebases.
88 * The result of the function is undefined if one of the timestamps
89 * is outside the int64_t range when represented in the others timebase.
90 * @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
91 */
92 int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b);
93
94
95 #endif /* AVUTIL_MATHEMATICS_H */