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/*
 * Copyright (C) 2005 Josef Cejka
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include<softfloat.h>

float32 addFloat32(float32 a, float32 b);
float32 subFloat32(float32 a, float32 b);
inline int isFloat32NaN(float32 f);
inline int isFloat32SigNaN(float32 f);

float __addsf3(float a, float b)
{
    float32 fa, fb;
    fa.f=a;
    fb.f=b;
    if (fa.parts.sign!=fb.parts.sign) return subFloat32(fa,fb).f;
    return addFloat32(fa,fb).f;
};

float __subsf3(float a, float b)
{
    float32 fa, fb;
    fa.f=a;
    fb.f=b;
    if (fa.parts.sign!=fb.parts.sign) return addFloat32(fa,fb).f;
    return subFloat32(fa,fb).f;
};

float __negsf2(float a)
{
    float32 fa;
    fa.f=a;
    fa.parts.sign=!fa.parts.sign;
    return fa.f;
};

double __negdf2(double a)
{
    float64 fa;
    fa.d=a;
    fa.parts.sign=!fa.parts.sign;
    return fa.d;
};

/** Add two Float32 numbers with same signs
 */
float32 addFloat32(float32 a, float32 b)
{
    int expdiff;
    __u32 exp1,exp2,mant1,mant2;
    
    expdiff=a.parts.exp - b.parts.exp;
    if (expdiff<0) {
        if (isFloat32NaN(b)) {
            //TODO: fix SigNaN
            if (isFloat32SigNaN(b)) {
            };
            return b;
        };
        
        if (b.parts.exp==0xFF) { 
            return b;
        }
        
        mant1=b.parts.mantisa;
        exp1=b.parts.exp;
        mant2=a.parts.mantisa;
        exp2=a.parts.exp;
        expdiff*=-1;
    } else {
        if (isFloat32NaN(a)) {
            //TODO: fix SigNaN
            if ((isFloat32SigNaN(a))||(isFloat32SigNaN(b))) {
            };
            return a;
        };
        
        if (a.parts.exp==0xFF) { 
            return a;
        }
        
        mant1=a.parts.mantisa;
        exp1=a.parts.exp;
        mant2=b.parts.mantisa;
        exp2=b.parts.exp;
    };
    
    if (exp1==0) {
        //both are denormalized
        mant1+=mant2;
        if (mant1&0xF00000) {
            a.parts.exp=1;
        };
        a.parts.mantisa=mant1;
        return a;
    };
    
    // create some space for rounding
    mant1<<=6;
    mant2<<=6;
    
    mant1|=0x20000000; //add hidden bit
    
    
    if (exp2==0) {
        --expdiff;  
    } else {
        mant2|=0x20000000; //hidden bit
    };
    
    mant2>>=expdiff;
    mant1+=mant2;
done:
    if (mant1&0x40000000) {
        ++exp1;
        mant1>>=1;
    };
    
    //rounding - if first bit after mantisa is set then round up
    mant1+=0x20;
    
    a.parts.exp=exp1;
    a.parts.mantisa=mant1>>6;
    return a;
};

/** Substract two float32 numbers with same signs
 */
float32 subFloat32(float32 a, float32 b)
{
    
    
};

inline int isFloat32NaN(float32 f)
{   /* NaN : exp = 0xff and nonzero mantisa */
    return ((f.parts.exp==0xFF)&&(f.parts.mantisa));
};

inline int isFloat32SigNaN(float32 f)
{   /* SigNaN : exp = 0xff mantisa = 1xxxxx..x (binary), where at least one x is nonzero */
    return ((f.parts.exp==0xFF)&&(f.parts.mantisa>0x400000));
};