softfloat.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

/*
 * copyright (c) 2006 Michael Niedermayer <[e-mail]>
 *
 * 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
 */

#include <inttypes.h>
#include <stdio.h>
#include <assert.h>
#include "softfloat.h"
#include "common.h"
#include "log.h"

#undef printf

int main(){
    SoftFloat one= av_int2sf(1, 0);
    SoftFloat sf1, sf2;
    double d1, d2;
    int i, j;
av_log_level = AV_LOG_DEBUG;

    d1= 1;
    for(i= 0; i<10; i++){
        d1= 1/(d1+1);
    }
    printf("test1 double=%d\n", (int)(d1 * (1<<24)));

    sf1= one;
    for(i= 0; i<10; i++){
        sf1= av_div_sf(one, av_normalize_sf(av_add_sf(one, sf1)));
    }
    printf("test1 sf    =%d\n", av_sf2int(sf1, 24));


    for(i= 0; i<100; i++){
        START_TIMER
        d1= i;
        d2= i/100.0;
        for(j= 0; j<1000; j++){
            d1= (d1+1)*d2;
        }
        STOP_TIMER("float add mul")
    }
    printf("test2 double=%d\n", (int)(d1 * (1<<24)));

    for(i= 0; i<100; i++){
        START_TIMER
        sf1= av_int2sf(i, 0);
        sf2= av_div_sf(av_int2sf(i, 2), av_int2sf(200, 3));
        for(j= 0; j<1000; j++){
            sf1= av_mul_sf(av_add_sf(sf1, one),sf2);
        }
        STOP_TIMER("softfloat add mul")
    }
    printf("test2 sf    =%d (%d %d)\n", av_sf2int(sf1, 24), sf1.exp, sf1.mant);
    return 0;
}