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comparison lib/libavutil/rational.h @ 2134:992d2e6f907d

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preparation for libavcodec
author zipi
date Tue, 31 Dec 2013 14:52:14 +0000
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2133:e378232bfd36 2134:992d2e6f907d
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 <limits.h>
33 #include "attributes.h"
34
35 /**
36 * @addtogroup lavu_math
37 * @{
38 */
39
40 /**
41 * rational number numerator/denominator
42 */
43 typedef 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 */
55 static 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 */
69 static 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 */
83 int 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 */
91 AVRational 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 */
99 AVRational 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 */
107 AVRational 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 */
115 AVRational av_sub_q(AVRational b, AVRational c) av_const;
116
117 /**
118 * Invert a rational.
119 * @param q value
120 * @return 1 / q
121 */
122 static av_always_inline AVRational av_inv_q(AVRational q)
123 {
124 AVRational r = { q.den, q.num };
125 return r;
126 }
127
128 /**
129 * Convert a double precision floating point number to a rational.
130 * inf is expressed as {1,0} or {-1,0} depending on the sign.
131 *
132 * @param d double to convert
133 * @param max the maximum allowed numerator and denominator
134 * @return (AVRational) d
135 */
136 AVRational av_d2q(double d, int max) av_const;
137
138 /**
139 * @return 1 if q1 is nearer to q than q2, -1 if q2 is nearer
140 * than q1, 0 if they have the same distance.
141 */
142 int av_nearer_q(AVRational q, AVRational q1, AVRational q2);
143
144 /**
145 * Find the nearest value in q_list to q.
146 * @param q_list an array of rationals terminated by {0, 0}
147 * @return the index of the nearest value found in the array
148 */
149 int av_find_nearest_q_idx(AVRational q, const AVRational* q_list);
150
151 /**
152 * @}
153 */
154
155 #endif /* AVUTIL_RATIONAL_H */