Line data Source code
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 : */
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 0 : static inline int av_cmp_q(AVRational a, AVRational b){
56 0 : const int64_t tmp= a.num * (int64_t)b.den - b.num * (int64_t)a.den;
57 :
58 0 : if(tmp) return ((tmp ^ a.den ^ b.den)>>63)|1;
59 0 : else if(b.den && a.den) return 0;
60 0 : else if(a.num && b.num) return (a.num>>31) - (b.num>>31);
61 0 : 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 */
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