Subversion Repositories Kolibri OS

Rev

Blame | Last modification | View Log | RSS feed

  1. /*
  2.  * arbitrary precision integers
  3.  * Copyright (c) 2004 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. /**
  23.  * @file
  24.  * arbitrary precision integers
  25.  * @author Michael Niedermayer <michaelni@gmx.at>
  26.  */
  27.  
  28. #include "common.h"
  29. #include "integer.h"
  30. #include "avassert.h"
  31.  
  32. static const AVInteger zero_i;
  33.  
  34. AVInteger av_add_i(AVInteger a, AVInteger b){
  35.     int i, carry=0;
  36.  
  37.     for(i=0; i<AV_INTEGER_SIZE; i++){
  38.         carry= (carry>>16) + a.v[i] + b.v[i];
  39.         a.v[i]= carry;
  40.     }
  41.     return a;
  42. }
  43.  
  44. AVInteger av_sub_i(AVInteger a, AVInteger b){
  45.     int i, carry=0;
  46.  
  47.     for(i=0; i<AV_INTEGER_SIZE; i++){
  48.         carry= (carry>>16) + a.v[i] - b.v[i];
  49.         a.v[i]= carry;
  50.     }
  51.     return a;
  52. }
  53.  
  54. int av_log2_i(AVInteger a){
  55.     int i;
  56.  
  57.     for(i=AV_INTEGER_SIZE-1; i>=0; i--){
  58.         if(a.v[i])
  59.             return av_log2_16bit(a.v[i]) + 16*i;
  60.     }
  61.     return -1;
  62. }
  63.  
  64. AVInteger av_mul_i(AVInteger a, AVInteger b){
  65.     AVInteger out;
  66.     int i, j;
  67.     int na= (av_log2_i(a)+16) >> 4;
  68.     int nb= (av_log2_i(b)+16) >> 4;
  69.  
  70.     memset(&out, 0, sizeof(out));
  71.  
  72.     for(i=0; i<na; i++){
  73.         unsigned int carry=0;
  74.  
  75.         if(a.v[i])
  76.             for(j=i; j<AV_INTEGER_SIZE && j-i<=nb; j++){
  77.                 carry= (carry>>16) + out.v[j] + a.v[i]*b.v[j-i];
  78.                 out.v[j]= carry;
  79.             }
  80.     }
  81.  
  82.     return out;
  83. }
  84.  
  85. int av_cmp_i(AVInteger a, AVInteger b){
  86.     int i;
  87.     int v= (int16_t)a.v[AV_INTEGER_SIZE-1] - (int16_t)b.v[AV_INTEGER_SIZE-1];
  88.     if(v) return (v>>16)|1;
  89.  
  90.     for(i=AV_INTEGER_SIZE-2; i>=0; i--){
  91.         int v= a.v[i] - b.v[i];
  92.         if(v) return (v>>16)|1;
  93.     }
  94.     return 0;
  95. }
  96.  
  97. AVInteger av_shr_i(AVInteger a, int s){
  98.     AVInteger out;
  99.     int i;
  100.  
  101.     for(i=0; i<AV_INTEGER_SIZE; i++){
  102.         unsigned int index= i + (s>>4);
  103.         unsigned int v=0;
  104.         if(index+1<AV_INTEGER_SIZE) v = a.v[index+1]<<16;
  105.         if(index  <AV_INTEGER_SIZE) v+= a.v[index  ];
  106.         out.v[i]= v >> (s&15);
  107.     }
  108.     return out;
  109. }
  110.  
  111. AVInteger av_mod_i(AVInteger *quot, AVInteger a, AVInteger b){
  112.     int i= av_log2_i(a) - av_log2_i(b);
  113.     AVInteger quot_temp;
  114.     if(!quot) quot = &quot_temp;
  115.  
  116.     if ((int16_t)a.v[AV_INTEGER_SIZE-1] < 0) {
  117.         a = av_mod_i(quot, av_sub_i(zero_i, a), b);
  118.         *quot = av_sub_i(zero_i, *quot);
  119.         return av_sub_i(zero_i, a);
  120.     }
  121.  
  122.     av_assert2((int16_t)a.v[AV_INTEGER_SIZE-1] >= 0 && (int16_t)b.v[AV_INTEGER_SIZE-1] >= 0);
  123.     av_assert2(av_log2_i(b)>=0);
  124.  
  125.     if(i > 0)
  126.         b= av_shr_i(b, -i);
  127.  
  128.     memset(quot, 0, sizeof(AVInteger));
  129.  
  130.     while(i-- >= 0){
  131.         *quot= av_shr_i(*quot, -1);
  132.         if(av_cmp_i(a, b) >= 0){
  133.             a= av_sub_i(a, b);
  134.             quot->v[0] += 1;
  135.         }
  136.         b= av_shr_i(b, 1);
  137.     }
  138.     return a;
  139. }
  140.  
  141. AVInteger av_div_i(AVInteger a, AVInteger b){
  142.     AVInteger quot;
  143.     av_mod_i(&quot, a, b);
  144.     return quot;
  145. }
  146.  
  147. AVInteger av_int2i(int64_t a){
  148.     AVInteger out;
  149.     int i;
  150.  
  151.     for(i=0; i<AV_INTEGER_SIZE; i++){
  152.         out.v[i]= a;
  153.         a>>=16;
  154.     }
  155.     return out;
  156. }
  157.  
  158. int64_t av_i2int(AVInteger a){
  159.     int i;
  160.     int64_t out=(int8_t)a.v[AV_INTEGER_SIZE-1];
  161.  
  162.     for(i= AV_INTEGER_SIZE-2; i>=0; i--){
  163.         out = (out<<16) + a.v[i];
  164.     }
  165.     return out;
  166. }
  167.  
  168. #ifdef TEST
  169.  
  170. const uint8_t ff_log2_tab[256]={
  171.         0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
  172.         5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
  173.         6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
  174.         6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
  175.         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  176.         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  177.         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  178.         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
  179. };
  180.  
  181. int main(void){
  182.     int64_t a,b;
  183.  
  184.     for(a=7; a<256*256*256; a+=13215){
  185.         for(b=3; b<256*256*256; b+=27118){
  186.             AVInteger ai= av_int2i(a);
  187.             AVInteger bi= av_int2i(b);
  188.  
  189.             av_assert0(av_i2int(ai) == a);
  190.             av_assert0(av_i2int(bi) == b);
  191.             av_assert0(av_i2int(av_add_i(ai,bi)) == a+b);
  192.             av_assert0(av_i2int(av_sub_i(ai,bi)) == a-b);
  193.             av_assert0(av_i2int(av_mul_i(ai,bi)) == a*b);
  194.             av_assert0(av_i2int(av_shr_i(ai, 9)) == a>>9);
  195.             av_assert0(av_i2int(av_shr_i(ai,-9)) == a<<9);
  196.             av_assert0(av_i2int(av_shr_i(ai, 17)) == a>>17);
  197.             av_assert0(av_i2int(av_shr_i(ai,-17)) == a<<17);
  198.             av_assert0(av_log2_i(ai) == av_log2(a));
  199.             av_assert0(av_i2int(av_div_i(ai,bi)) == a/b);
  200.         }
  201.     }
  202.     return 0;
  203. }
  204. #endif
  205.