Libav 0.7.1
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00001 /* 00002 * arbitrary precision integers 00003 * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at> 00004 * 00005 * This file is part of Libav. 00006 * 00007 * Libav is free software; you can redistribute it and/or 00008 * modify it under the terms of the GNU Lesser General Public 00009 * License as published by the Free Software Foundation; either 00010 * version 2.1 of the License, or (at your option) any later version. 00011 * 00012 * Libav is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00015 * Lesser General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU Lesser General Public 00018 * License along with Libav; if not, write to the Free Software 00019 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00020 */ 00021 00028 #include "common.h" 00029 #include "integer.h" 00030 00031 AVInteger av_add_i(AVInteger a, AVInteger b){ 00032 int i, carry=0; 00033 00034 for(i=0; i<AV_INTEGER_SIZE; i++){ 00035 carry= (carry>>16) + a.v[i] + b.v[i]; 00036 a.v[i]= carry; 00037 } 00038 return a; 00039 } 00040 00041 AVInteger av_sub_i(AVInteger a, AVInteger b){ 00042 int i, carry=0; 00043 00044 for(i=0; i<AV_INTEGER_SIZE; i++){ 00045 carry= (carry>>16) + a.v[i] - b.v[i]; 00046 a.v[i]= carry; 00047 } 00048 return a; 00049 } 00050 00051 int av_log2_i(AVInteger a){ 00052 int i; 00053 00054 for(i=AV_INTEGER_SIZE-1; i>=0; i--){ 00055 if(a.v[i]) 00056 return av_log2_16bit(a.v[i]) + 16*i; 00057 } 00058 return -1; 00059 } 00060 00061 AVInteger av_mul_i(AVInteger a, AVInteger b){ 00062 AVInteger out; 00063 int i, j; 00064 int na= (av_log2_i(a)+16) >> 4; 00065 int nb= (av_log2_i(b)+16) >> 4; 00066 00067 memset(&out, 0, sizeof(out)); 00068 00069 for(i=0; i<na; i++){ 00070 unsigned int carry=0; 00071 00072 if(a.v[i]) 00073 for(j=i; j<AV_INTEGER_SIZE && j-i<=nb; j++){ 00074 carry= (carry>>16) + out.v[j] + a.v[i]*b.v[j-i]; 00075 out.v[j]= carry; 00076 } 00077 } 00078 00079 return out; 00080 } 00081 00082 int av_cmp_i(AVInteger a, AVInteger b){ 00083 int i; 00084 int v= (int16_t)a.v[AV_INTEGER_SIZE-1] - (int16_t)b.v[AV_INTEGER_SIZE-1]; 00085 if(v) return (v>>16)|1; 00086 00087 for(i=AV_INTEGER_SIZE-2; i>=0; i--){ 00088 int v= a.v[i] - b.v[i]; 00089 if(v) return (v>>16)|1; 00090 } 00091 return 0; 00092 } 00093 00094 AVInteger av_shr_i(AVInteger a, int s){ 00095 AVInteger out; 00096 int i; 00097 00098 for(i=0; i<AV_INTEGER_SIZE; i++){ 00099 unsigned int index= i + (s>>4); 00100 unsigned int v=0; 00101 if(index+1<AV_INTEGER_SIZE) v = a.v[index+1]<<16; 00102 if(index <AV_INTEGER_SIZE) v+= a.v[index ]; 00103 out.v[i]= v >> (s&15); 00104 } 00105 return out; 00106 } 00107 00108 AVInteger av_mod_i(AVInteger *quot, AVInteger a, AVInteger b){ 00109 int i= av_log2_i(a) - av_log2_i(b); 00110 AVInteger quot_temp; 00111 if(!quot) quot = "_temp; 00112 00113 assert((int16_t)a[AV_INTEGER_SIZE-1] >= 0 && (int16_t)b[AV_INTEGER_SIZE-1] >= 0); 00114 assert(av_log2(b)>=0); 00115 00116 if(i > 0) 00117 b= av_shr_i(b, -i); 00118 00119 memset(quot, 0, sizeof(AVInteger)); 00120 00121 while(i-- >= 0){ 00122 *quot= av_shr_i(*quot, -1); 00123 if(av_cmp_i(a, b) >= 0){ 00124 a= av_sub_i(a, b); 00125 quot->v[0] += 1; 00126 } 00127 b= av_shr_i(b, 1); 00128 } 00129 return a; 00130 } 00131 00132 AVInteger av_div_i(AVInteger a, AVInteger b){ 00133 AVInteger quot; 00134 av_mod_i(", a, b); 00135 return quot; 00136 } 00137 00138 AVInteger av_int2i(int64_t a){ 00139 AVInteger out; 00140 int i; 00141 00142 for(i=0; i<AV_INTEGER_SIZE; i++){ 00143 out.v[i]= a; 00144 a>>=16; 00145 } 00146 return out; 00147 } 00148 00149 int64_t av_i2int(AVInteger a){ 00150 int i; 00151 int64_t out=(int8_t)a.v[AV_INTEGER_SIZE-1]; 00152 00153 for(i= AV_INTEGER_SIZE-2; i>=0; i--){ 00154 out = (out<<16) + a.v[i]; 00155 } 00156 return out; 00157 } 00158 00159 #ifdef TEST 00160 #undef NDEBUG 00161 #include <assert.h> 00162 00163 const uint8_t ff_log2_tab[256]={ 00164 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, 00165 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, 00166 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, 00167 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, 00168 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, 00169 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, 00170 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, 00171 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 00172 }; 00173 00174 int main(void){ 00175 int64_t a,b; 00176 00177 for(a=7; a<256*256*256; a+=13215){ 00178 for(b=3; b<256*256*256; b+=27118){ 00179 AVInteger ai= av_int2i(a); 00180 AVInteger bi= av_int2i(b); 00181 00182 assert(av_i2int(ai) == a); 00183 assert(av_i2int(bi) == b); 00184 assert(av_i2int(av_add_i(ai,bi)) == a+b); 00185 assert(av_i2int(av_sub_i(ai,bi)) == a-b); 00186 assert(av_i2int(av_mul_i(ai,bi)) == a*b); 00187 assert(av_i2int(av_shr_i(ai, 9)) == a>>9); 00188 assert(av_i2int(av_shr_i(ai,-9)) == a<<9); 00189 assert(av_i2int(av_shr_i(ai, 17)) == a>>17); 00190 assert(av_i2int(av_shr_i(ai,-17)) == a<<17); 00191 assert(av_log2_i(ai) == av_log2(a)); 00192 assert(av_i2int(av_div_i(ai,bi)) == a/b); 00193 } 00194 } 00195 return 0; 00196 } 00197 #endif