Pure, const and malloc attributes to libavutil.
[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 rational.h
24 * Rational numbers.
25 * @author Michael Niedermayer <michaelni@gmx.at>
26 */
27
28 #ifndef FFMPEG_RATIONAL_H
29 #define FFMPEG_RATIONAL_H
30
31 #include <stdint.h>
32
33 /**
34 * Rational number num/den.
35 */
36 typedef struct AVRational{
37 int num; ///< numerator
38 int den; ///< denominator
39 } AVRational;
40
41 /**
42 * Compare two rationals.
43 * @param a first rational
44 * @param b second rational
45 * @return 0 if a==b, 1 if a>b and -1 if a<b.
46 */
47 static inline int av_cmp_q(AVRational a, AVRational b){
48 const int64_t tmp= a.num * (int64_t)b.den - b.num * (int64_t)a.den;
49
50 if(tmp) return (tmp>>63)|1;
51 else return 0;
52 }
53
54 /**
55 * Rational to double conversion.
56 * @param a rational to convert
57 * @return (double) a
58 */
59 static inline double av_q2d(AVRational a){
60 return a.num / (double) a.den;
61 }
62
63 /**
64 * Reduce a fraction.
65 * This is useful for framerate calculations.
66 * @param dst_nom destination numerator
67 * @param dst_den destination denominator
68 * @param nom source numerator
69 * @param den source denominator
70 * @param max the maximum allowed for dst_nom & dst_den
71 * @return 1 if exact, 0 otherwise
72 */
73 int av_reduce(int *dst_nom, int *dst_den, int64_t nom, int64_t den, int64_t max);
74
75 /**
76 * Multiplies two rationals.
77 * @param b first rational.
78 * @param c second rational.
79 * @return b*c.
80 */
81 AVRational av_mul_q(AVRational b, AVRational c) av_const;
82
83 /**
84 * Divides one rational by another.
85 * @param b first rational.
86 * @param c second rational.
87 * @return b/c.
88 */
89 AVRational av_div_q(AVRational b, AVRational c) av_const;
90
91 /**
92 * Adds two rationals.
93 * @param b first rational.
94 * @param c second rational.
95 * @return b+c.
96 */
97 AVRational av_add_q(AVRational b, AVRational c) av_const;
98
99 /**
100 * Subtracts one rational from another.
101 * @param b first rational.
102 * @param c second rational.
103 * @return b-c.
104 */
105 AVRational av_sub_q(AVRational b, AVRational c) av_const;
106
107 /**
108 * Converts a double precision floating point number to a rational.
109 * @param d double to convert
110 * @param max the maximum allowed numerator and denominator
111 * @return (AVRational) d.
112 */
113 AVRational av_d2q(double d, int max) av_const;
114
115 #endif /* FFMPEG_RATIONAL_H */