2 * arbitrary precision integers
3 * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
5 * This file is part of FFmpeg.
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.
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.
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
25 * arbitrary precision integers.
26 * @author Michael Niedermayer <michaelni@gmx.at>
32 AVInteger av_add_i(AVInteger a, AVInteger b){
35 for(i=0; i<AV_INTEGER_SIZE; i++){
36 carry= (carry>>16) + a.v[i] + b.v[i];
42 AVInteger av_sub_i(AVInteger a, AVInteger b){
45 for(i=0; i<AV_INTEGER_SIZE; i++){
46 carry= (carry>>16) + a.v[i] - b.v[i];
53 * returns the rounded down value of the logarithm of base 2 of the given AVInteger.
54 * this is simply the index of the most significant bit which is 1. Or 0 of all bits are 0
56 int av_log2_i(AVInteger a){
59 for(i=AV_INTEGER_SIZE-1; i>=0; i--){
61 return av_log2_16bit(a.v[i]) + 16*i;
66 AVInteger av_mul_i(AVInteger a, AVInteger b){
69 int na= (av_log2_i(a)+16) >> 4;
70 int nb= (av_log2_i(b)+16) >> 4;
72 memset(&out, 0, sizeof(out));
78 for(j=i; j<AV_INTEGER_SIZE && j-i<=nb; j++){
79 carry= (carry>>16) + out.v[j] + a.v[i]*b.v[j-i];
88 * returns 0 if a==b, 1 if a>b and -1 if a<b.
90 int av_cmp_i(AVInteger a, AVInteger b){
92 int v= (int16_t)a.v[AV_INTEGER_SIZE-1] - (int16_t)b.v[AV_INTEGER_SIZE-1];
93 if(v) return (v>>16)|1;
95 for(i=AV_INTEGER_SIZE-2; i>=0; i--){
96 int v= a.v[i] - b.v[i];
97 if(v) return (v>>16)|1;
104 * @param s the number of bits by which the value should be shifted right, may be negative for shifting left
106 AVInteger av_shr_i(AVInteger a, int s){
110 for(i=0; i<AV_INTEGER_SIZE; i++){
111 int index= i + (s>>4);
113 if(index+1<AV_INTEGER_SIZE && index+1>=0) v = a.v[index+1]<<16;
114 if(index <AV_INTEGER_SIZE && index >=0) v+= a.v[index ];
115 out.v[i]= v >> (s&15);
122 * @param quot a/b will be stored here
124 AVInteger av_mod_i(AVInteger *quot, AVInteger a, AVInteger b){
125 int i= av_log2_i(a) - av_log2_i(b);
127 if(!quot) quot = "_temp;
129 assert((int16_t)a[AV_INTEGER_SIZE-1] >= 0 && (int16_t)b[AV_INTEGER_SIZE-1] >= 0);
130 assert(av_log2(b)>=0);
135 memset(quot, 0, sizeof(AVInteger));
138 *quot= av_shr_i(*quot, -1);
139 if(av_cmp_i(a, b) >= 0){
151 AVInteger av_div_i(AVInteger a, AVInteger b){
153 av_mod_i(", a, b);
158 * converts the given int64_t to an AVInteger.
160 AVInteger av_int2i(int64_t a){
164 for(i=0; i<AV_INTEGER_SIZE; i++){
172 * converts the given AVInteger to an int64_t.
173 * if the AVInteger is too large to fit into an int64_t,
174 * then only the least significant 64bit will be used
176 int64_t av_i2int(AVInteger a){
178 int64_t out=(int8_t)a.v[AV_INTEGER_SIZE-1];
180 for(i= AV_INTEGER_SIZE-2; i>=0; i--){
181 out = (out<<16) + a.v[i];
190 const uint8_t ff_log2_tab[256]={
191 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,
192 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,
193 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,
194 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,
195 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,
196 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,
197 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,
198 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
204 for(a=7; a<256*256*256; a+=13215){
205 for(b=3; b<256*256*256; b+=27118){
206 AVInteger ai= av_int2i(a);
207 AVInteger bi= av_int2i(b);
209 assert(av_i2int(ai) == a);
210 assert(av_i2int(bi) == b);
211 assert(av_i2int(av_add_i(ai,bi)) == a+b);
212 assert(av_i2int(av_sub_i(ai,bi)) == a-b);
213 assert(av_i2int(av_mul_i(ai,bi)) == a*b);
214 assert(av_i2int(av_shr_i(ai, 9)) == a>>9);
215 assert(av_i2int(av_shr_i(ai,-9)) == a<<9);
216 assert(av_i2int(av_shr_i(ai, 17)) == a>>17);
217 assert(av_i2int(av_shr_i(ai,-17)) == a<<17);
218 assert(av_log2_i(ai) == av_log2(a));
219 assert(av_i2int(av_div_i(ai,bi)) == a/b);