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