Fix av_cmp_q() with negative denominators.
[libav.git] / libavutil / rational.h
CommitLineData
5ff85f1d 1/*
89c9ff50 2 * rational numbers
5ff85f1d
MN
3 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
4 *
b78e7197
DB
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
5ff85f1d
MN
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
b78e7197 10 * version 2.1 of the License, or (at your option) any later version.
5ff85f1d 11 *
b78e7197 12 * FFmpeg is distributed in the hope that it will be useful,
5ff85f1d
MN
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
b78e7197 18 * License along with FFmpeg; if not, write to the Free Software
5509bffa 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
5ff85f1d 20 */
115329f1 21
5ff85f1d 22/**
ba87f080 23 * @file
89c9ff50 24 * rational numbers
5ff85f1d
MN
25 * @author Michael Niedermayer <michaelni@gmx.at>
26 */
27
98790382
SS
28#ifndef AVUTIL_RATIONAL_H
29#define AVUTIL_RATIONAL_H
5ff85f1d 30
99545457 31#include <stdint.h>
2ed6f399 32#include "attributes.h"
99545457 33
5c07b9e9 34/**
89c9ff50 35 * rational number numerator/denominator
5c07b9e9 36 */
5ff85f1d 37typedef struct AVRational{
5c07b9e9
MN
38 int num; ///< numerator
39 int den; ///< denominator
5ff85f1d
MN
40} AVRational;
41
5c07b9e9 42/**
49bd8e4b 43 * Compare two rationals.
1c95ef8b
DB
44 * @param a first rational
45 * @param b second rational
89c9ff50 46 * @return 0 if a==b, 1 if a>b and -1 if a<b
5c07b9e9 47 */
5ff85f1d
MN
48static 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
8a47d90b 51 if(tmp) return ((tmp ^ a.den ^ b.den)>>63)|1;
5c07b9e9 52 else return 0;
5ff85f1d
MN
53}
54
5c07b9e9 55/**
49bd8e4b 56 * Convert rational to double.
1c95ef8b
DB
57 * @param a rational to convert
58 * @return (double) a
5c07b9e9 59 */
5ff85f1d
MN
60static inline double av_q2d(AVRational a){
61 return a.num / (double) a.den;
62}
63
c11c2bc2 64/**
49bd8e4b 65 * Reduce a fraction.
804de96a 66 * This is useful for framerate calculations.
674bd4f6 67 * @param dst_num destination numerator
1c95ef8b 68 * @param dst_den destination denominator
674bd4f6 69 * @param num source numerator
1c95ef8b 70 * @param den source denominator
674bd4f6 71 * @param max the maximum allowed for dst_num & dst_den
c11c2bc2
AS
72 * @return 1 if exact, 0 otherwise
73 */
674bd4f6 74int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max);
c11c2bc2 75
0b006599 76/**
49bd8e4b 77 * Multiply two rationals.
89c9ff50
DB
78 * @param b first rational
79 * @param c second rational
80 * @return b*c
0b006599 81 */
85074d3c 82AVRational av_mul_q(AVRational b, AVRational c) av_const;
0b006599
DB
83
84/**
49bd8e4b 85 * Divide one rational by another.
89c9ff50
DB
86 * @param b first rational
87 * @param c second rational
88 * @return b/c
0b006599 89 */
85074d3c 90AVRational av_div_q(AVRational b, AVRational c) av_const;
0b006599
DB
91
92/**
49bd8e4b 93 * Add two rationals.
89c9ff50
DB
94 * @param b first rational
95 * @param c second rational
96 * @return b+c
0b006599 97 */
85074d3c 98AVRational av_add_q(AVRational b, AVRational c) av_const;
0b006599
DB
99
100/**
49bd8e4b 101 * Subtract one rational from another.
89c9ff50
DB
102 * @param b first rational
103 * @param c second rational
104 * @return b-c
0b006599 105 */
85074d3c 106AVRational av_sub_q(AVRational b, AVRational c) av_const;
0b006599
DB
107
108/**
49bd8e4b 109 * Convert a double precision floating point number to a rational.
0b006599
DB
110 * @param d double to convert
111 * @param max the maximum allowed numerator and denominator
89c9ff50 112 * @return (AVRational) d
0b006599 113 */
85074d3c 114AVRational av_d2q(double d, int max) av_const;
5ff85f1d 115
05b90fc0 116/**
bf7e799c
SS
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.
05b90fc0
SS
119 */
120int av_nearer_q(AVRational q, AVRational q1, AVRational q2);
121
122/**
49bd8e4b 123 * Find the nearest value in q_list to q.
05b90fc0
SS
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 */
127int av_find_nearest_q_idx(AVRational q, const AVRational* q_list);
128
98790382 129#endif /* AVUTIL_RATIONAL_H */