1/*
2 * rational numbers
3 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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 * Libav 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 Libav; 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 <limits.h>
33#include "attributes.h"
34
35/**
36 * @addtogroup lavu_math
37 * @{
38 */
39
40/**
41 * rational number numerator/denominator
42 */
43typedef struct AVRational{
44    int num; ///< numerator
45    int den; ///< denominator
46} AVRational;
47
48/**
49 * Compare two rationals.
50 * @param a first rational
51 * @param b second rational
52 * @return 0 if a==b, 1 if a>b, -1 if a<b, and INT_MIN if one of the
53 * values is of the form 0/0
54 */
55static inline int av_cmp_q(AVRational a, AVRational b){
56    const int64_t tmp= a.num * (int64_t)b.den - b.num * (int64_t)a.den;
57
58    if(tmp) return ((tmp ^ a.den ^ b.den)>>63)|1;
59    else if(b.den && a.den) return 0;
60    else if(a.num && b.num) return (a.num>>31) - (b.num>>31);
61    else                    return INT_MIN;
62}
63
64/**
65 * Convert rational to double.
66 * @param a rational to convert
67 * @return (double) a
68 */
69static inline double av_q2d(AVRational a){
70    return a.num / (double) a.den;
71}
72
73/**
74 * Reduce a fraction.
75 * This is useful for framerate calculations.
76 * @param dst_num destination numerator
77 * @param dst_den destination denominator
78 * @param num source numerator
79 * @param den source denominator
80 * @param max the maximum allowed for dst_num & dst_den
81 * @return 1 if exact, 0 otherwise
82 */
83int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max);
84
85/**
86 * Multiply two rationals.
87 * @param b first rational
88 * @param c second rational
89 * @return b*c
90 */
91AVRational av_mul_q(AVRational b, AVRational c) av_const;
92
93/**
94 * Divide one rational by another.
95 * @param b first rational
96 * @param c second rational
97 * @return b/c
98 */
99AVRational av_div_q(AVRational b, AVRational c) av_const;
100
101/**
102 * Add two rationals.
103 * @param b first rational
104 * @param c second rational
105 * @return b+c
106 */
107AVRational av_add_q(AVRational b, AVRational c) av_const;
108
109/**
110 * Subtract one rational from another.
111 * @param b first rational
112 * @param c second rational
113 * @return b-c
114 */
115AVRational av_sub_q(AVRational b, AVRational c) av_const;
116
117/**
118 * Convert a double precision floating point number to a rational.
119 * inf is expressed as {1,0} or {-1,0} depending on the sign.
120 *
121 * @param d double to convert
122 * @param max the maximum allowed numerator and denominator
123 * @return (AVRational) d
124 */
125AVRational av_d2q(double d, int max) av_const;
126
127/**
128 * @return 1 if q1 is nearer to q than q2, -1 if q2 is nearer
129 * than q1, 0 if they have the same distance.
130 */
131int av_nearer_q(AVRational q, AVRational q1, AVRational q2);
132
133/**
134 * Find the nearest value in q_list to q.
135 * @param q_list an array of rationals terminated by {0, 0}
136 * @return the index of the nearest value found in the array
137 */
138int av_find_nearest_q_idx(AVRational q, const AVRational* q_list);
139
140/**
141 * @}
142 */
143
144#endif /* AVUTIL_RATIONAL_H */
145