Cleaned pixdesc.c file in libavutil
[libav.git] / libavutil / rational.c
CommitLineData
5ff85f1d 1/*
89c9ff50 2 * rational numbers
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3 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
4 *
2912e87a 5 * This file is part of Libav.
b78e7197 6 *
2912e87a 7 * Libav is free software; you can redistribute it and/or
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8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
b78e7197 10 * version 2.1 of the License, or (at your option) any later version.
5ff85f1d 11 *
2912e87a 12 * Libav is distributed in the hope that it will be useful,
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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
2912e87a 18 * License along with Libav; if not, write to the Free Software
5509bffa 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
5ff85f1d 20 */
115329f1 21
5ff85f1d 22/**
ba87f080 23 * @file
89c9ff50 24 * rational numbers
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25 * @author Michael Niedermayer <michaelni@gmx.at>
26 */
27
b64b4134 28#include "avassert.h"
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29//#include <math.h>
30#include <limits.h>
115329f1 31
5ff85f1d 32#include "common.h"
c11c2bc2 33#include "mathematics.h"
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34#include "rational.h"
35
674bd4f6 36int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max){
c11c2bc2 37 AVRational a0={0,1}, a1={1,0};
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38 int sign= (num<0) ^ (den<0);
39 int64_t gcd= av_gcd(FFABS(num), FFABS(den));
c11c2bc2 40
6880edab 41 if(gcd){
674bd4f6 42 num = FFABS(num)/gcd;
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43 den = FFABS(den)/gcd;
44 }
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45 if(num<=max && den<=max){
46 a1= (AVRational){num, den};
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47 den=0;
48 }
115329f1 49
c11c2bc2 50 while(den){
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51 uint64_t x = num / den;
52 int64_t next_den= num - den*x;
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53 int64_t a2n= x*a1.num + a0.num;
54 int64_t a2d= x*a1.den + a0.den;
55
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56 if(a2n > max || a2d > max){
57 if(a1.num) x= (max - a0.num) / a1.num;
58 if(a1.den) x= FFMIN(x, (max - a0.den) / a1.den);
59
674bd4f6 60 if (den*(2*x*a1.den + a0.den) > num*a1.den)
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61 a1 = (AVRational){x*a1.num + a0.num, x*a1.den + a0.den};
62 break;
63 }
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64
65 a0= a1;
66 a1= (AVRational){a2n, a2d};
674bd4f6 67 num= den;
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68 den= next_den;
69 }
b926b628 70 av_assert2(av_gcd(a1.num, a1.den) <= 1U);
115329f1 71
674bd4f6 72 *dst_num = sign ? -a1.num : a1.num;
c11c2bc2 73 *dst_den = a1.den;
115329f1 74
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75 return den==0;
76}
77
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78AVRational av_mul_q(AVRational b, AVRational c){
79 av_reduce(&b.num, &b.den, b.num * (int64_t)c.num, b.den * (int64_t)c.den, INT_MAX);
80 return b;
81}
82
83AVRational av_div_q(AVRational b, AVRational c){
79dc59b7 84 return av_mul_q(b, (AVRational){c.den, c.num});
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85}
86
87AVRational av_add_q(AVRational b, AVRational c){
88 av_reduce(&b.num, &b.den, b.num * (int64_t)c.den + c.num * (int64_t)b.den, b.den * (int64_t)c.den, INT_MAX);
89 return b;
90}
91
92AVRational av_sub_q(AVRational b, AVRational c){
79dc59b7 93 return av_add_q(b, (AVRational){-c.num, c.den});
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94}
95
96AVRational av_d2q(double d, int max){
97 AVRational a;
79dc59b7 98#define LOG2 0.69314718055994530941723212145817656807550013436025
1405782c
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99 int exponent;
100 int64_t den;
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101 if (isnan(d))
102 return (AVRational){0,0};
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103 if (isinf(d))
104 return (AVRational){ d<0 ? -1:1, 0 };
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105 exponent = FFMAX( (int)(log(fabs(d) + 1e-20)/LOG2), 0);
106 den = 1LL << (61 - exponent);
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107 av_reduce(&a.num, &a.den, (int64_t)(d * den + 0.5), den, max);
108
109 return a;
110}
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111
112int av_nearer_q(AVRational q, AVRational q1, AVRational q2)
113{
114 /* n/d is q, a/b is the median between q1 and q2 */
115 int64_t a = q1.num * (int64_t)q2.den + q2.num * (int64_t)q1.den;
116 int64_t b = 2 * (int64_t)q1.den * q2.den;
117
118 /* rnd_up(a*d/b) > n => a*d/b > n */
119 int64_t x_up = av_rescale_rnd(a, q.den, b, AV_ROUND_UP);
120
121 /* rnd_down(a*d/b) < n => a*d/b < n */
122 int64_t x_down = av_rescale_rnd(a, q.den, b, AV_ROUND_DOWN);
123
124 return ((x_up > q.num) - (x_down < q.num)) * av_cmp_q(q2, q1);
125}
126
127int av_find_nearest_q_idx(AVRational q, const AVRational* q_list)
128{
129 int i, nearest_q_idx = 0;
130 for(i=0; q_list[i].den; i++)
131 if (av_nearer_q(q, q_list[i], q_list[nearest_q_idx]) > 0)
132 nearest_q_idx = i;
133
134 return nearest_q_idx;
135}
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136
137#ifdef TEST
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138int main(void)
139{
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140 AVRational a,b;
141 for(a.num=-2; a.num<=2; a.num++){
142 for(a.den=-2; a.den<=2; a.den++){
143 for(b.num=-2; b.num<=2; b.num++){
144 for(b.den=-2; b.den<=2; b.den++){
145 int c= av_cmp_q(a,b);
146 double d= av_q2d(a) == av_q2d(b) ? 0 : (av_q2d(a) - av_q2d(b));
147 if(d>0) d=1;
148 else if(d<0) d=-1;
149 else if(d != d) d= INT_MIN;
150 if(c!=d) av_log(0, AV_LOG_ERROR, "%d/%d %d/%d, %d %f\n", a.num, a.den, b.num, b.den, c,d);
151 }
152 }
153 }
154 }
812f2376 155 return 0;
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156}
157#endif