2dd0c2c5948e5480877bb13ca6421e7a31428794
[libav.git] / libavutil / rational.h
1 /*
2 * rational numbers
3 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file
24 * rational numbers
25 * @author Michael Niedermayer <michaelni@gmx.at>
26 */
27
28 #ifndef AVUTIL_RATIONAL_H
29 #define AVUTIL_RATIONAL_H
30
31 #include <stdint.h>
32 #include "attributes.h"
33
34 /**
35 * rational number numerator/denominator
36 */
37 typedef struct AVRational{
38 int num; ///< numerator
39 int den; ///< denominator
40 } AVRational;
41
42 /**
43 * Compare two rationals.
44 * @param a first rational
45 * @param b second rational
46 * @return 0 if a==b, 1 if a>b and -1 if a<b
47 */
48 static inline int av_cmp_q(AVRational a, AVRational b){
49 const int64_t tmp= a.num * (int64_t)b.den - b.num * (int64_t)a.den;
50
51 if(tmp) return (tmp>>63)|1;
52 else return 0;
53 }
54
55 /**
56 * Convert rational to double.
57 * @param a rational to convert
58 * @return (double) a
59 */
60 static inline double av_q2d(AVRational a){
61 return a.num / (double) a.den;
62 }
63
64 /**
65 * Reduce a fraction.
66 * This is useful for framerate calculations.
67 * @param dst_num destination numerator
68 * @param dst_den destination denominator
69 * @param num source numerator
70 * @param den source denominator
71 * @param max the maximum allowed for dst_num & dst_den
72 * @return 1 if exact, 0 otherwise
73 */
74 int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max);
75
76 /**
77 * Multiply two rationals.
78 * @param b first rational
79 * @param c second rational
80 * @return b*c
81 */
82 AVRational av_mul_q(AVRational b, AVRational c) av_const;
83
84 /**
85 * Divide one rational by another.
86 * @param b first rational
87 * @param c second rational
88 * @return b/c
89 */
90 AVRational av_div_q(AVRational b, AVRational c) av_const;
91
92 /**
93 * Add two rationals.
94 * @param b first rational
95 * @param c second rational
96 * @return b+c
97 */
98 AVRational av_add_q(AVRational b, AVRational c) av_const;
99
100 /**
101 * Subtract one rational from another.
102 * @param b first rational
103 * @param c second rational
104 * @return b-c
105 */
106 AVRational av_sub_q(AVRational b, AVRational c) av_const;
107
108 /**
109 * Convert a double precision floating point number to a rational.
110 * @param d double to convert
111 * @param max the maximum allowed numerator and denominator
112 * @return (AVRational) d
113 */
114 AVRational av_d2q(double d, int max) av_const;
115
116 /**
117 * @return 1 if q1 is nearer to q than q2, -1 if q2 is nearer
118 * than q1, 0 if they have the same distance.
119 */
120 int av_nearer_q(AVRational q, AVRational q1, AVRational q2);
121
122 /**
123 * Find the nearest value in q_list to q.
124 * @param q_list an array of rationals terminated by {0, 0}
125 * @return the index of the nearest value found in the array
126 */
127 int av_find_nearest_q_idx(AVRational q, const AVRational* q_list);
128
129 #endif /* AVUTIL_RATIONAL_H */