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122 lines
3.1 KiB
C
122 lines
3.1 KiB
C
/*
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* Copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* miscellaneous math routines and tables
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*/
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#include <stdint.h>
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#include <limits.h>
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#include "mathematics.h"
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#include "version.h"
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int64_t av_gcd(int64_t a, int64_t b)
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{
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if (b)
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return av_gcd(b, a % b);
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else
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return a;
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}
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int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding rnd)
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{
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int64_t r = 0;
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if (c <= 0 || b < 0 || rnd == 4 || rnd > 5)
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return INT64_MIN;
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if (a < 0 && a != INT64_MIN)
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return -av_rescale_rnd(-a, b, c, rnd ^ ((rnd >> 1) & 1));
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if (rnd == AV_ROUND_NEAR_INF)
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r = c / 2;
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else if (rnd & 1)
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r = c - 1;
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if (b <= INT_MAX && c <= INT_MAX) {
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if (a <= INT_MAX)
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return (a * b + r) / c;
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else
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return a / c * b + (a % c * b + r) / c;
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} else {
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uint64_t a0 = a & 0xFFFFFFFF;
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uint64_t a1 = a >> 32;
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uint64_t b0 = b & 0xFFFFFFFF;
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uint64_t b1 = b >> 32;
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uint64_t t1 = a0 * b1 + a1 * b0;
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uint64_t t1a = t1 << 32;
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int i;
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a0 = a0 * b0 + t1a;
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a1 = a1 * b1 + (t1 >> 32) + (a0 < t1a);
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a0 += r;
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a1 += a0 < r;
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for (i = 63; i >= 0; i--) {
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a1 += a1 + ((a0 >> i) & 1);
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t1 += t1;
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if (c <= a1) {
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a1 -= c;
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t1++;
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}
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}
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return t1;
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}
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}
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int64_t av_rescale(int64_t a, int64_t b, int64_t c)
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{
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return av_rescale_rnd(a, b, c, AV_ROUND_NEAR_INF);
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}
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int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq,
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enum AVRounding rnd)
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{
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int64_t b = bq.num * (int64_t)cq.den;
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int64_t c = cq.num * (int64_t)bq.den;
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return av_rescale_rnd(a, b, c, rnd);
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}
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int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
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{
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return av_rescale_q_rnd(a, bq, cq, AV_ROUND_NEAR_INF);
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}
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int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b)
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{
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int64_t a = tb_a.num * (int64_t)tb_b.den;
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int64_t b = tb_b.num * (int64_t)tb_a.den;
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if (av_rescale_rnd(ts_a, a, b, AV_ROUND_DOWN) < ts_b)
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return -1;
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if (av_rescale_rnd(ts_b, b, a, AV_ROUND_DOWN) < ts_a)
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return 1;
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return 0;
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}
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int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod)
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{
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int64_t c = (a - b) & (mod - 1);
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if (c > (mod >> 1))
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c -= mod;
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return c;
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}
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