source: mainline/softfloat/generic/arithmetic.c@ e649dfa

/*
 * 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<sftypes.h>
#include<arithmetic.h>

/** 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
        };
        
        if (expdiff>24) {
             goto done; 
             };
        
        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)
{
        
        
};