PeerStreamer

/*

 * Copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>

 *

 * This library 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 of the License, or (at your option) any later version.

 *

 * This library 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 this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file mathematics.c

 * Miscellaneous math routines and tables.

 */

#include "common.h"

#include "mathematics.h"

const uint8_t ff_sqrt_tab[128]={

        0, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5,

        5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,

        8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,

        9, 9, 9, 9,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,11,11,11,11,11,11,11

};

const uint8_t ff_log2_tab[256]={

        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,

        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,

        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,

        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,

        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,

        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,

        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,

        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

};

int64_t ff_gcd(int64_t a, int64_t b){

    if(b) return ff_gcd(b, a%b);

    else  return a;

}

int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding rnd){

    int64_t r=0;

    assert(c > 0);

    assert(b >=0);

    assert(rnd >=0 && rnd<=5 && rnd!=4);

    if(a<0 && a != INT64_MIN) return -av_rescale_rnd(-a, b, c, rnd ^ ((rnd>>1)&1));

    if(rnd==AV_ROUND_NEAR_INF) r= c/2;

    else if(rnd&1)             r= c-1;

    if(b<=INT_MAX && c<=INT_MAX){

        if(a<=INT_MAX)

            return (a * b + r)/c;

        else

            return a/c*b + (a%c*b + r)/c;

    }else{

#if 1

        uint64_t a0= a&0xFFFFFFFF;

        uint64_t a1= a>>32;

        uint64_t b0= b&0xFFFFFFFF;

        uint64_t b1= b>>32;

        uint64_t t1= a0*b1 + a1*b0;

        uint64_t t1a= t1<<32;

        int i;

        a0 = a0*b0 + t1a;

        a1 = a1*b1 + (t1>>32) + (a0<t1a);

        a0 += r;

        a1 += a0<r;

        for(i=63; i>=0; i--){

//            int o= a1 & 0x8000000000000000ULL;

            a1+= a1 + ((a0>>i)&1);

            t1+=t1;

            if(/*o || */c <= a1){

                a1 -= c;

                t1++;

            }

        }

        return t1;

    }

#else

        AVInteger ai;

        ai= av_mul_i(av_int2i(a), av_int2i(b));

        ai= av_add_i(ai, av_int2i(r));

        return av_i2int(av_div_i(ai, av_int2i(c)));

    }

#endif

}

int64_t av_rescale(int64_t a, int64_t b, int64_t c){

    return av_rescale_rnd(a, b, c, AV_ROUND_NEAR_INF);

}

int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq){

    int64_t b= bq.num * (int64_t)cq.den;

    int64_t c= cq.num * (int64_t)bq.den;

    return av_rescale_rnd(a, b, c, AV_ROUND_NEAR_INF);

}

#if 0

#include "integer.h"

#undef printf

main(){

    int64_t a,b,c,d,e;

    for(a=7; a<(1LL<<62); a+=a/3+1){

        for(b=3; b<(1LL<<62); b+=b/4+1){

            for(c=9; c<(1LL<<62); c+=(c*2)/5+3){

                int64_t r= c/2;

                AVInteger ai;

                ai= av_mul_i(av_int2i(a), av_int2i(b));

                ai= av_add_i(ai, av_int2i(r));

                d= av_i2int(av_div_i(ai, av_int2i(c)));

                e= av_rescale(a,b,c);

                if((double)a * (double)b / (double)c > (1LL<<63))

                    continue;

                if(d!=e) printf("%Ld*%Ld/%Ld= %Ld=%Ld\n", a, b, c, d, e);

            }

        }

    }

}

#endif