PeerStreamer

/*

 * Copyright (c) 2006 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

 */

#ifndef AVUTIL_SOFTFLOAT_H

#define AVUTIL_SOFTFLOAT_H

#include <stdint.h>

#include "common.h"

#define MIN_EXP -126

#define MAX_EXP  126

#define ONE_BITS 29

typedef struct SoftFloat{

    int32_t  exp;

    int32_t mant;

}SoftFloat;

static av_const SoftFloat av_normalize_sf(SoftFloat a){

    if(a.mant){

#if 1

        while((a.mant + 0x20000000U)<0x40000000U){

            a.mant += a.mant;

            a.exp  -= 1;

        }

#else

        int s=ONE_BITS + 1 - av_log2(a.mant ^ (a.mant<<1));

        a.exp   -= s;

        a.mant <<= s;

#endif

        if(a.exp < MIN_EXP){

            a.exp = MIN_EXP;

            a.mant= 0;

        }

    }else{

        a.exp= MIN_EXP;

    }

    return a;

}

static inline av_const SoftFloat av_normalize1_sf(SoftFloat a){

#if 1

    if(a.mant + 0x40000000 < 0){

        a.exp++;

        a.mant>>=1;

    }

    return a;

#elif 1

    int t= a.mant + 0x40000000 < 0;

    return (SoftFloat){a.exp+t, a.mant>>t};

#else

    int t= (a.mant + 0x40000000U)>>31;

    return (SoftFloat){a.exp+t, a.mant>>t};

#endif

}

/**

 * @return Will not be more denormalized than a+b. So if either input is

 *         normalized, then the output will not be worse then the other input.

 *         If both are normalized, then the output will be normalized.

 */

static inline av_const SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){

    a.exp += b.exp;

    a.mant = (a.mant * (int64_t)b.mant) >> ONE_BITS;

    return av_normalize1_sf(a);

}

/**

 * b has to be normalized and not zero.

 * @return Will not be more denormalized than a.

 */

static av_const SoftFloat av_div_sf(SoftFloat a, SoftFloat b){

    a.exp -= b.exp+1;

    a.mant = ((int64_t)a.mant<<(ONE_BITS+1)) / b.mant;

    return av_normalize1_sf(a);

}

static inline av_const int av_cmp_sf(SoftFloat a, SoftFloat b){

    int t= a.exp - b.exp;

    if(t<0) return (a.mant >> (-t)) -  b.mant      ;

    else    return  a.mant          - (b.mant >> t);

}

static inline av_const SoftFloat av_add_sf(SoftFloat a, SoftFloat b){

    int t= a.exp - b.exp;

    if(t<0) return av_normalize1_sf((SoftFloat){b.exp, b.mant + (a.mant >> (-t))});

    else    return av_normalize1_sf((SoftFloat){a.exp, a.mant + (b.mant >>   t )});

}

static inline av_const SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){

    return av_add_sf(a, (SoftFloat){b.exp, -b.mant});

}

//FIXME sqrt, log, exp, pow, sin, cos

static inline av_const SoftFloat av_int2sf(int v, int frac_bits){

    return av_normalize_sf((SoftFloat){ONE_BITS-frac_bits, v});

}

/**

 * Rounding is to -inf.

 */

static inline av_const int av_sf2int(SoftFloat v, int frac_bits){

    v.exp += frac_bits - ONE_BITS;

    if(v.exp >= 0) return v.mant <<  v.exp ;

    else           return v.mant >>(-v.exp);

}

#endif /* AVUTIL_SOFTFLOAT_H */