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 */
av_make_q(int num,int den)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 */
av_cmp_q(AVRational a,AVRational b)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 */
av_q2d(AVRational a)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 */
av_inv_q(AVRational q)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 * Converts a AVRational to a IEEE 32bit float.
164 *
165 * The float is returned in a uint32_t and its value is platform indepenant.
166 */
167 uint32_t av_q2intfloat(AVRational q);
168
169 /**
170 * @}
171 */
172
173 #endif /* AVUTIL_RATIONAL_H */
174