git.sesse.net Git - ffmpeg/blob - libavutil/mathematics.c

   1 /*
   2  * Copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
   3  *
   4  * This file is part of Libav.
   5  *
   6  * Libav is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * Libav is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with Libav; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 /**
  22  * @file
  23  * miscellaneous math routines and tables
  24  */
  25
  26 #include <assert.h>
  27 #include <stdint.h>
  28 #include <limits.h>
  29
  30 #include "mathematics.h"
  31 #include "version.h"
  32
  33 #if FF_API_AV_REVERSE
  34 const uint8_t av_reverse[256]={
  35 0x00,0x80,0x40,0xC0,0x20,0xA0,0x60,0xE0,0x10,0x90,0x50,0xD0,0x30,0xB0,0x70,0xF0,
  36 0x08,0x88,0x48,0xC8,0x28,0xA8,0x68,0xE8,0x18,0x98,0x58,0xD8,0x38,0xB8,0x78,0xF8,
  37 0x04,0x84,0x44,0xC4,0x24,0xA4,0x64,0xE4,0x14,0x94,0x54,0xD4,0x34,0xB4,0x74,0xF4,
  38 0x0C,0x8C,0x4C,0xCC,0x2C,0xAC,0x6C,0xEC,0x1C,0x9C,0x5C,0xDC,0x3C,0xBC,0x7C,0xFC,
  39 0x02,0x82,0x42,0xC2,0x22,0xA2,0x62,0xE2,0x12,0x92,0x52,0xD2,0x32,0xB2,0x72,0xF2,
  40 0x0A,0x8A,0x4A,0xCA,0x2A,0xAA,0x6A,0xEA,0x1A,0x9A,0x5A,0xDA,0x3A,0xBA,0x7A,0xFA,
  41 0x06,0x86,0x46,0xC6,0x26,0xA6,0x66,0xE6,0x16,0x96,0x56,0xD6,0x36,0xB6,0x76,0xF6,
  42 0x0E,0x8E,0x4E,0xCE,0x2E,0xAE,0x6E,0xEE,0x1E,0x9E,0x5E,0xDE,0x3E,0xBE,0x7E,0xFE,
  43 0x01,0x81,0x41,0xC1,0x21,0xA1,0x61,0xE1,0x11,0x91,0x51,0xD1,0x31,0xB1,0x71,0xF1,
  44 0x09,0x89,0x49,0xC9,0x29,0xA9,0x69,0xE9,0x19,0x99,0x59,0xD9,0x39,0xB9,0x79,0xF9,
  45 0x05,0x85,0x45,0xC5,0x25,0xA5,0x65,0xE5,0x15,0x95,0x55,0xD5,0x35,0xB5,0x75,0xF5,
  46 0x0D,0x8D,0x4D,0xCD,0x2D,0xAD,0x6D,0xED,0x1D,0x9D,0x5D,0xDD,0x3D,0xBD,0x7D,0xFD,
  47 0x03,0x83,0x43,0xC3,0x23,0xA3,0x63,0xE3,0x13,0x93,0x53,0xD3,0x33,0xB3,0x73,0xF3,
  48 0x0B,0x8B,0x4B,0xCB,0x2B,0xAB,0x6B,0xEB,0x1B,0x9B,0x5B,0xDB,0x3B,0xBB,0x7B,0xFB,
  49 0x07,0x87,0x47,0xC7,0x27,0xA7,0x67,0xE7,0x17,0x97,0x57,0xD7,0x37,0xB7,0x77,0xF7,
  50 0x0F,0x8F,0x4F,0xCF,0x2F,0xAF,0x6F,0xEF,0x1F,0x9F,0x5F,0xDF,0x3F,0xBF,0x7F,0xFF,
  51 };
  52 #endif
  53
  54 int64_t av_gcd(int64_t a, int64_t b){
  55     if(b) return av_gcd(b, a%b);
  56     else  return a;
  57 }
  58
  59 int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding rnd){
  60     int64_t r=0;
  61     assert(c > 0);
  62     assert(b >=0);
  63     assert((unsigned)rnd<=5 && rnd!=4);
  64
  65     if(a<0 && a != INT64_MIN) return -av_rescale_rnd(-a, b, c, rnd ^ ((rnd>>1)&1));
  66
  67     if(rnd==AV_ROUND_NEAR_INF) r= c/2;
  68     else if(rnd&1)             r= c-1;
  69
  70     if(b<=INT_MAX && c<=INT_MAX){
  71         if(a<=INT_MAX)
  72             return (a * b + r)/c;
  73         else
  74             return a/c*b + (a%c*b + r)/c;
  75     }else{
  76 #if 1
  77         uint64_t a0= a&0xFFFFFFFF;
  78         uint64_t a1= a>>32;
  79         uint64_t b0= b&0xFFFFFFFF;
  80         uint64_t b1= b>>32;
  81         uint64_t t1= a0*b1 + a1*b0;
  82         uint64_t t1a= t1<<32;
  83         int i;
  84
  85         a0 = a0*b0 + t1a;
  86         a1 = a1*b1 + (t1>>32) + (a0<t1a);
  87         a0 += r;
  88         a1 += a0<r;
  89
  90         for(i=63; i>=0; i--){
  91 //            int o= a1 & 0x8000000000000000ULL;
  92             a1+= a1 + ((a0>>i)&1);
  93             t1+=t1;
  94             if(/*o || */c <= a1){
  95                 a1 -= c;
  96                 t1++;
  97             }
  98         }
  99         return t1;
 100     }
 101 #else
 102         AVInteger ai;
 103         ai= av_mul_i(av_int2i(a), av_int2i(b));
 104         ai= av_add_i(ai, av_int2i(r));
 105
 106         return av_i2int(av_div_i(ai, av_int2i(c)));
 107     }
 108 #endif
 109 }
 110
 111 int64_t av_rescale(int64_t a, int64_t b, int64_t c){
 112     return av_rescale_rnd(a, b, c, AV_ROUND_NEAR_INF);
 113 }
 114
 115 int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq,
 116                          enum AVRounding rnd)
 117 {
 118     int64_t b= bq.num * (int64_t)cq.den;
 119     int64_t c= cq.num * (int64_t)bq.den;
 120     return av_rescale_rnd(a, b, c, rnd);
 121 }
 122
 123 int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
 124 {
 125     return av_rescale_q_rnd(a, bq, cq, AV_ROUND_NEAR_INF);
 126 }
 127
 128 int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b){
 129     int64_t a= tb_a.num * (int64_t)tb_b.den;
 130     int64_t b= tb_b.num * (int64_t)tb_a.den;
 131     if (av_rescale_rnd(ts_a, a, b, AV_ROUND_DOWN) < ts_b) return -1;
 132     if (av_rescale_rnd(ts_b, b, a, AV_ROUND_DOWN) < ts_a) return  1;
 133     return 0;
 134 }
 135
 136 int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod){
 137     int64_t c= (a-b) & (mod-1);
 138     if(c > (mod>>1))
 139         c-= mod;
 140     return c;
 141 }