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mathematics.h
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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 
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  * Compute the greatest common divisor of a and b.
81  *
82  * @return gcd of a and b up to sign; if a >= 0 and b >= 0, return value is >= 0;
83  * if a == 0 and b == 0, returns 0.
84  */
85 int64_t av_const av_gcd(int64_t a, int64_t b);
86 
87 /**
88  * Rescale a 64-bit integer with rounding to nearest.
89  * A simple a*b/c isn't possible as it can overflow.
90  */
91 int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const;
92 
93 /**
94  * Rescale a 64-bit integer with specified rounding.
95  * A simple a*b/c isn't possible as it can overflow.
96  *
97  * @return rescaled value a, or if AV_ROUND_PASS_MINMAX is set and a is
98  * INT64_MIN or INT64_MAX then a is passed through unchanged.
99  */
100 int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding) av_const;
101 
102 /**
103  * Rescale a 64-bit integer by 2 rational numbers.
104  */
105 int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const;
106 
107 /**
108  * Rescale a 64-bit integer by 2 rational numbers with specified rounding.
109  *
110  * @return rescaled value a, or if AV_ROUND_PASS_MINMAX is set and a is
111  * INT64_MIN or INT64_MAX then a is passed through unchanged.
112  */
113 int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq,
114  enum AVRounding) av_const;
115 
116 /**
117  * Compare 2 timestamps each in its own timebases.
118  * The result of the function is undefined if one of the timestamps
119  * is outside the int64_t range when represented in the others timebase.
120  * @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
121  */
122 int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b);
123 
124 /**
125  * Compare 2 integers modulo mod.
126  * That is we compare integers a and b for which only the least
127  * significant log2(mod) bits are known.
128  *
129  * @param mod must be a power of 2
130  * @return a negative value if a is smaller than b
131  * a positive value if a is greater than b
132  * 0 if a equals b
133  */
134 int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod);
135 
136 /**
137  * Rescale a timestamp while preserving known durations.
138  *
139  * @param in_ts Input timestamp
140  * @param in_tb Input timebase
141  * @param fs_tb Duration and *last timebase
142  * @param duration duration till the next call
143  * @param out_tb Output timebase
144  */
145 int64_t av_rescale_delta(AVRational in_tb, int64_t in_ts, AVRational fs_tb, int duration, int64_t *last, AVRational out_tb);
146 
147 /**
148  * Add a value to a timestamp.
149  *
150  * This function guarantees that when the same value is repeatly added that
151  * no accumulation of rounding errors occurs.
152  *
153  * @param ts Input timestamp
154  * @param ts_tb Input timestamp timebase
155  * @param inc value to add to ts
156  * @param inc_tb inc timebase
157  */
158 int64_t av_add_stable(AVRational ts_tb, int64_t ts, AVRational inc_tb, int64_t inc);
159 
160 
161  /**
162  * @}
163  */
164 
165 #endif /* AVUTIL_MATHEMATICS_H */
#define av_const
Definition: attributes.h:76
int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding) av_const
Rescale a 64-bit integer with specified rounding.
Definition: mathematics.c:58
const char * b
Definition: vf_curves.c:113
AVRounding
Definition: mathematics.h:70
Macro definitions for various function/variable attributes.
Round toward +infinity.
Definition: mathematics.h:74
int64_t duration
Definition: movenc.c:63
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const
Rescale a 64-bit integer by 2 rational numbers.
Definition: mathematics.c:142
Round away from zero.
Definition: mathematics.h:72
Round to nearest and halfway cases away from zero.
Definition: mathematics.h:75
int64_t av_const av_gcd(int64_t a, int64_t b)
Compute the greatest common divisor of a and b.
Definition: mathematics.c:37
int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b)
Compare 2 timestamps each in its own timebases.
Definition: mathematics.c:147
int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq, enum AVRounding) av_const
Rescale a 64-bit integer by 2 rational numbers with specified rounding.
Definition: mathematics.c:134
int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const
Rescale a 64-bit integer with rounding to nearest.
Definition: mathematics.c:129
Round toward zero.
Definition: mathematics.h:71
int64_t av_rescale_delta(AVRational in_tb, int64_t in_ts, AVRational fs_tb, int duration, int64_t *last, AVRational out_tb)
Rescale a timestamp while preserving known durations.
Definition: mathematics.c:168
rational number numerator/denominator
Definition: rational.h:43
Round toward -infinity.
Definition: mathematics.h:73
rational numbers
int64_t av_add_stable(AVRational ts_tb, int64_t ts, AVRational inc_tb, int64_t inc)
Add a value to a timestamp.
Definition: mathematics.c:191
static double c[64]
Flag to pass INT64_MIN/MAX through instead of rescaling, this avoids special cases for AV_NOPTS_VALUE...
Definition: mathematics.h:76
int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod)
Compare 2 integers modulo mod.
Definition: mathematics.c:160