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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 | * Create a rational. | |
50 | * Useful for compilers that do not support compound literals. | |
51 | * @note The return value is not reduced. | |
52 | */ | |
53 | static inline AVRational av_make_q(int num, int den) | |
54 | { | |
55 | AVRational r = { num, den }; | |
56 | return r; | |
57 | } | |
58 | ||
59 | /** | |
60 | * Compare two rationals. | |
61 | * @param a first rational | |
62 | * @param b second rational | |
63 | * @return 0 if a==b, 1 if a>b, -1 if a<b, and INT_MIN if one of the | |
64 | * values is of the form 0/0 | |
65 | */ | |
66 | static inline int av_cmp_q(AVRational a, AVRational b){ | |
67 | const int64_t tmp= a.num * (int64_t)b.den - b.num * (int64_t)a.den; | |
68 | ||
69 | if(tmp) return (int)((tmp ^ a.den ^ b.den)>>63)|1; | |
70 | else if(b.den && a.den) return 0; | |
71 | else if(a.num && b.num) return (a.num>>31) - (b.num>>31); | |
72 | else return INT_MIN; | |
73 | } | |
74 | ||
75 | /** | |
76 | * Convert rational to double. | |
77 | * @param a rational to convert | |
78 | * @return (double) a | |
79 | */ | |
80 | static inline double av_q2d(AVRational a){ | |
81 | return a.num / (double) a.den; | |
82 | } | |
83 | ||
84 | /** | |
85 | * Reduce a fraction. | |
86 | * This is useful for framerate calculations. | |
87 | * @param dst_num destination numerator | |
88 | * @param dst_den destination denominator | |
89 | * @param num source numerator | |
90 | * @param den source denominator | |
91 | * @param max the maximum allowed for dst_num & dst_den | |
92 | * @return 1 if exact, 0 otherwise | |
93 | */ | |
94 | int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max); | |
95 | ||
96 | /** | |
97 | * Multiply two rationals. | |
98 | * @param b first rational | |
99 | * @param c second rational | |
100 | * @return b*c | |
101 | */ | |
102 | AVRational av_mul_q(AVRational b, AVRational c) av_const; | |
103 | ||
104 | /** | |
105 | * Divide one rational by another. | |
106 | * @param b first rational | |
107 | * @param c second rational | |
108 | * @return b/c | |
109 | */ | |
110 | AVRational av_div_q(AVRational b, AVRational c) av_const; | |
111 | ||
112 | /** | |
113 | * Add two rationals. | |
114 | * @param b first rational | |
115 | * @param c second rational | |
116 | * @return b+c | |
117 | */ | |
118 | AVRational av_add_q(AVRational b, AVRational c) av_const; | |
119 | ||
120 | /** | |
121 | * Subtract one rational from another. | |
122 | * @param b first rational | |
123 | * @param c second rational | |
124 | * @return b-c | |
125 | */ | |
126 | AVRational av_sub_q(AVRational b, AVRational c) av_const; | |
127 | ||
128 | /** | |
129 | * Invert a rational. | |
130 | * @param q value | |
131 | * @return 1 / q | |
132 | */ | |
133 | static av_always_inline AVRational av_inv_q(AVRational q) | |
134 | { | |
135 | AVRational r = { q.den, q.num }; | |
136 | return r; | |
137 | } | |
138 | ||
139 | /** | |
140 | * Convert a double precision floating point number to a rational. | |
141 | * inf is expressed as {1,0} or {-1,0} depending on the sign. | |
142 | * | |
143 | * @param d double to convert | |
144 | * @param max the maximum allowed numerator and denominator | |
145 | * @return (AVRational) d | |
146 | */ | |
147 | AVRational av_d2q(double d, int max) av_const; | |
148 | ||
149 | /** | |
150 | * @return 1 if q1 is nearer to q than q2, -1 if q2 is nearer | |
151 | * than q1, 0 if they have the same distance. | |
152 | */ | |
153 | int av_nearer_q(AVRational q, AVRational q1, AVRational q2); | |
154 | ||
155 | /** | |
156 | * Find the nearest value in q_list to q. | |
157 | * @param q_list an array of rationals terminated by {0, 0} | |
158 | * @return the index of the nearest value found in the array | |
159 | */ | |
160 | int av_find_nearest_q_idx(AVRational q, const AVRational* q_list); | |
161 | ||
162 | /** | |
163 | * @} | |
164 | */ | |
165 | ||
166 | #endif /* AVUTIL_RATIONAL_H */ |