/* * 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 = &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(&quot, 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;}