/* * arbitrary precision integers * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at> * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * arbitrary precision integers * @author Michael Niedermayer <michaelni@gmx.at> */ #include <string.h> #include "integer.h" #include "avassert.h" #include "intmath.h" static const AVInteger zero_i; AVInteger av_add_i(AVInteger a, AVInteger b){ int i, carry=0; for(i=0; i<AV_INTEGER_SIZE; i++){ carry= (carry>>16) + a.v[i] + b.v[i]; a.v[i]= carry; } return a; } AVInteger av_sub_i(AVInteger a, AVInteger b){ int i, carry=0; for(i=0; i<AV_INTEGER_SIZE; i++){ carry= (carry>>16) + a.v[i] - b.v[i]; a.v[i]= carry; } return a; } int av_log2_i(AVInteger a){ int i; for(i=AV_INTEGER_SIZE-1; i>=0; i--){ if(a.v[i]) return av_log2_16bit(a.v[i]) + 16*i; } return -1; } AVInteger av_mul_i(AVInteger a, AVInteger b){ AVInteger out; int i, j; int na= (av_log2_i(a)+16) >> 4; int nb= (av_log2_i(b)+16) >> 4; memset(&out, 0, sizeof(out)); for(i=0; i<na; i++){ unsigned int carry=0; if(a.v[i]) for(j=i; j<AV_INTEGER_SIZE && j-i<=nb; j++){ carry= (carry>>16) + out.v[j] + a.v[i]*(unsigned)b.v[j-i]; out.v[j]= carry; } } return out; } int av_cmp_i(AVInteger a, AVInteger b){ int i; int v= (int16_t)a.v[AV_INTEGER_SIZE-1] - (int16_t)b.v[AV_INTEGER_SIZE-1]; if(v) return (v>>16)|1; for(i=AV_INTEGER_SIZE-2; i>=0; i--){ int v= a.v[i] - b.v[i]; if(v) return (v>>16)|1; } return 0; } AVInteger av_shr_i(AVInteger a, int s){ AVInteger out; int i; for(i=0; i<AV_INTEGER_SIZE; i++){ unsigned int index= i + (s>>4); unsigned int v=0; if(index+1<AV_INTEGER_SIZE) v = a.v[index+1]<<16; if(index <AV_INTEGER_SIZE) v+= a.v[index ]; out.v[i]= v >> (s&15); } return out; } AVInteger av_mod_i(AVInteger *quot, AVInteger a, AVInteger b){ int i= av_log2_i(a) - av_log2_i(b); AVInteger quot_temp; if(!quot) quot = "_temp; if ((int16_t)a.v[AV_INTEGER_SIZE-1] < 0) { a = av_mod_i(quot, av_sub_i(zero_i, a), b); *quot = av_sub_i(zero_i, *quot); return av_sub_i(zero_i, a); } av_assert2((int16_t)a.v[AV_INTEGER_SIZE-1] >= 0 && (int16_t)b.v[AV_INTEGER_SIZE-1] >= 0); av_assert2(av_log2_i(b)>=0); if(i > 0) b= av_shr_i(b, -i); memset(quot, 0, sizeof(AVInteger)); while(i-- >= 0){ *quot= av_shr_i(*quot, -1); if(av_cmp_i(a, b) >= 0){ a= av_sub_i(a, b); quot->v[0] += 1; } b= av_shr_i(b, 1); } return a; } AVInteger av_div_i(AVInteger a, AVInteger b){ AVInteger quot; av_mod_i(", a, b); return quot; } AVInteger av_int2i(int64_t a){ AVInteger out; int i; for(i=0; i<AV_INTEGER_SIZE; i++){ out.v[i]= a; a>>=16; } return out; } int64_t av_i2int(AVInteger a){ int i; int64_t out=(int8_t)a.v[AV_INTEGER_SIZE-1]; for(i= AV_INTEGER_SIZE-2; i>=0; i--){ out = (out<<16) + a.v[i]; } return out; }