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/*
* rational numbers
* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* rational numbers
* @author Michael Niedermayer <michaelni@gmx.at>
*/
#include "avassert.h"
#include <limits.h>
#include "common.h"
#include "mathematics.h"
#include "rational.h"
int av_reduce(int *dst_num, int *dst_den,
int64_t num, int64_t den, int64_t max)
{
AVRational a0 = { 0, 1 }, a1 = { 1, 0 };
int sign = (num < 0) ^ (den < 0);
int64_t gcd = av_gcd(FFABS(num), FFABS(den));
if (gcd) {
num = FFABS(num) / gcd;
den = FFABS(den) / gcd;
}
if (num <= max && den <= max) {
a1 = (AVRational) { num, den };
den = 0;
}
while (den) {
uint64_t x = num / den;
int64_t next_den = num - den * x;
int64_t a2n = x * a1.num + a0.num;
int64_t a2d = x * a1.den + a0.den;
if (a2n > max || a2d > max) {
if (a1.num) x = (max - a0.num) / a1.num;
if (a1.den) x = FFMIN(x, (max - a0.den) / a1.den);
if (den * (2 * x * a1.den + a0.den) > num * a1.den)
a1 = (AVRational) { x * a1.num + a0.num, x * a1.den + a0.den };
break;
}
a0 = a1;
a1 = (AVRational) { a2n, a2d };
num = den;
den = next_den;
}
av_assert2(av_gcd(a1.num, a1.den) <= 1U);
*dst_num = sign ? -a1.num : a1.num;
*dst_den = a1.den;
return den == 0;
}
AVRational av_mul_q(AVRational b, AVRational c)
{
av_reduce(&b.num, &b.den,
b.num * (int64_t) c.num,
b.den * (int64_t) c.den, INT_MAX);
return b;
}
AVRational av_div_q(AVRational b, AVRational c)
{
return av_mul_q(b, (AVRational) { c.den, c.num });
}
AVRational av_add_q(AVRational b, AVRational c) {
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);
return b;
}
AVRational av_sub_q(AVRational b, AVRational c)
{
return av_add_q(b, (AVRational) { -c.num, c.den });
}
AVRational av_d2q(double d, int max)
{
AVRational a;
#define LOG2 0.69314718055994530941723212145817656807550013436025
int exponent;
int64_t den;
if (isnan(d))
return (AVRational) { 0,0 };
if (fabs(d) > INT_MAX + 3LL)
return (AVRational) { d < 0 ? -1 : 1, 0 };
exponent = FFMAX( (int)(log(fabs(d) + 1e-20)/LOG2), 0);
den = 1LL << (61 - exponent);
av_reduce(&a.num, &a.den, llrint(d * den), den, max);
return a;
}
int av_nearer_q(AVRational q, AVRational q1, AVRational q2)
{
/* n/d is q, a/b is the median between q1 and q2 */
int64_t a = q1.num * (int64_t)q2.den + q2.num * (int64_t)q1.den;
int64_t b = 2 * (int64_t)q1.den * q2.den;
/* rnd_up(a*d/b) > n => a*d/b > n */
int64_t x_up = av_rescale_rnd(a, q.den, b, AV_ROUND_UP);
/* rnd_down(a*d/b) < n => a*d/b < n */
int64_t x_down = av_rescale_rnd(a, q.den, b, AV_ROUND_DOWN);
return ((x_up > q.num) - (x_down < q.num)) * av_cmp_q(q2, q1);
}
int av_find_nearest_q_idx(AVRational q, const AVRational* q_list)
{
int i, nearest_q_idx = 0;
for (i = 0; q_list[i].den; i++)
if (av_nearer_q(q, q_list[i], q_list[nearest_q_idx]) > 0)
nearest_q_idx = i;
return nearest_q_idx;
}
#ifdef TEST
int main(void)
{
AVRational a,b,r;
for (a.num = -2; a.num <= 2; a.num++) {
for (a.den = -2; a.den <= 2; a.den++) {
for (b.num = -2; b.num <= 2; b.num++) {
for (b.den = -2; b.den <= 2; b.den++) {
int c = av_cmp_q(a,b);
double d = av_q2d(a) == av_q2d(b) ?
0 : (av_q2d(a) - av_q2d(b));
if (d > 0) d = 1;
else if (d < 0) d = -1;
else if (d != d) d = INT_MIN;
if (c != d)
av_log(NULL, AV_LOG_ERROR, "%d/%d %d/%d, %d %f\n", a.num,
a.den, b.num, b.den, c,d);
r = av_sub_q(av_add_q(b,a), b);
if(b.den && (r.num*a.den != a.num*r.den || !r.num != !a.num || !r.den != !a.den))
av_log(NULL, AV_LOG_ERROR, "%d/%d ", r.num, r.den);
}
}
}
}
return 0;
}
#endif
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