ffmpeg.libavutil.rational source code

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 module ffmpeg.libavutil.rational;
22 import std.stdint;
23 
24 @nogc nothrow extern(C):
25 
26 /**
27  * @addtogroup lavu_math
28  * @{
29  */
30 
31 /**
32  * rational number numerator/denominator
33  */
34 struct AVRational {
35 	int num;
36 	int den;
37 } 
38 
39 /**
40  * Create a rational.
41  * Useful for compilers that do not support compound literals.
42  * @note  The return value is not reduced.
43  */
44 static AVRational av_make_q(int num, int den)
45 {
46     AVRational r = { num, den };
47     return r;
48 }
49 
50 /**
51  * Compare two rationals.
52  * @param a first rational
53  * @param b second rational
54  * @return 0 if a==b, 1 if a>b, -1 if a<b, and INT_MIN if one of the
55  * values is of the form 0/0
56  */
57 static int av_cmp_q(AVRational a, AVRational b){
58     const int64_t tmp= a.num * cast(int64_t)b.den - b.num * cast(int64_t)a.den;
59 
60     if(tmp) return ((tmp ^ a.den ^ b.den)>>63)|1;
61     else if(b.den && a.den) return 0;
62     else if(a.num && b.num) return (a.num>>31) - (b.num>>31);
63     else                    return int.min;
64 }
65 
66 /**
67  * Convert rational to double.
68  * @param a rational to convert
69  * @return (double) a
70  */
71 static double av_q2d(AVRational a){
72     return a.num / cast(double) a.den;
73 }
74 
75 /**
76  * Reduce a fraction.
77  * This is useful for framerate calculations.
78  * @param dst_num destination numerator
79  * @param dst_den destination denominator
80  * @param num source numerator
81  * @param den source denominator
82  * @param max the maximum allowed for dst_num & dst_den
83  * @return 1 if exact, 0 otherwise
84  */
85 int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max);
86  
87  /**
88  * Multiply two rationals.
89  * @param b first rational
90  * @param c second rational
91  * @return b*c
92  */
93 AVRational av_mul_q(AVRational b, AVRational c);
94 
95 /**
96  * Divide one rational by another.
97  * @param b first rational
98  * @param c second rational
99  * @return b/c
100  */
101 AVRational av_div_q(AVRational b, AVRational c);
102 
103 /**
104  * Add two rationals.
105  * @param b first rational
106  * @param c second rational
107  * @return b+c
108  */
109 AVRational av_add_q(AVRational b, AVRational c);
110 
111 /**
112  * Subtract one rational from another.
113  * @param b first rational
114  * @param c second rational
115  * @return b-c
116  */
117 AVRational av_sub_q(AVRational b, AVRational c);
118 
119 /**
120  * Invert a rational.
121  * @param q value
122  * @return 1 / q
123  */
124 static AVRational av_inv_q(AVRational q)
125 {
126     AVRational r = { q.den, q.num };
127     return r;
128 }
129 
130 /**
131  * Convert a double precision floating point number to a rational.
132  * inf is expressed as {1,0} or {-1,0} depending on the sign.
133  *
134  * @param d double to convert
135  * @param max the maximum allowed numerator and denominator
136  * @return (AVRational) d
137  */
138 AVRational av_d2q(double d, int max);
139 
140 /**
141  * @return 1 if q1 is nearer to q than q2, -1 if q2 is nearer
142  * than q1, 0 if they have the same distance.
143  */
144 int av_nearer_q(AVRational q, AVRational q1, AVRational q2);
145 
146 /**
147  * Find the nearest value in q_list to q.
148  * @param q_list an array of rationals terminated by {0, 0}
149  * @return the index of the nearest value found in the array
150  */
151 int av_find_nearest_q_idx(AVRational q, const AVRational* q_list);
152 
153 /**
154  * Converts a AVRational to a IEEE 32bit float.
155  *
156  * The float is returned in a uint32_t and its value is platform indepenant.
157  */
158 uint32_t av_q2intfloat(AVRational q);