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