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 
22 module ffmpeg.libavutil.rational;
23 
24 /**
25  * @file
26  * rational numbers
27  * @author Michael Niedermayer <michaelni@gmx.at>
28  */
29 
30 import std.stdint;
31 
32 
33 @nogc nothrow extern(C):
34 
35 /**
36  * @addtogroup lavu_math
37  * @{
38  */
39 
40 /**
41  * rational number numerator/denominator
42  */
43 struct AVRational {
44 	int num;
45 	int den;
46 } 
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 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 int av_cmp_q(AVRational a, AVRational b){
67     const int64_t tmp= a.num * cast(int64_t)b.den - b.num * cast(int64_t)a.den;
68 
69     if(tmp) return ((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 double av_q2d(AVRational a){
81     return a.num / cast(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);
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);
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);
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);
127 
128 /**
129  * Invert a rational.
130  * @param q value
131  * @return 1 / q
132  */
133 static 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);
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 */