floatx80 floatx80_rem()

in nwfpe/softfloat.c [3069:3160]

• 89 lines of code
• 22 McCabe index (conditional complexity)

floatx80 floatx80_rem( struct roundingData *roundData, floatx80 a, floatx80 b )
{
    flag aSign, bSign, zSign;
    int32 aExp, bExp, expDiff;
    bits64 aSig0, aSig1, bSig;
    bits64 q, term0, term1, alternateASig0, alternateASig1;
    floatx80 z;

    aSig0 = extractFloatx80Frac( a );
    aExp = extractFloatx80Exp( a );
    aSign = extractFloatx80Sign( a );
    bSig = extractFloatx80Frac( b );
    bExp = extractFloatx80Exp( b );
    bSign = extractFloatx80Sign( b );
    if ( aExp == 0x7FFF ) {
        if (    (bits64) ( aSig0<<1 )
             || ( ( bExp == 0x7FFF ) && (bits64) ( bSig<<1 ) ) ) {
            return propagateFloatx80NaN( a, b );
        }
        goto invalid;
    }
    if ( bExp == 0x7FFF ) {
        if ( (bits64) ( bSig<<1 ) ) return propagateFloatx80NaN( a, b );
        return a;
    }
    if ( bExp == 0 ) {
        if ( bSig == 0 ) {
 invalid:
            roundData->exception |= float_flag_invalid;
            z.low = floatx80_default_nan_low;
            z.high = floatx80_default_nan_high;
            z.__padding = 0;
            return z;
        }
        normalizeFloatx80Subnormal( bSig, &bExp, &bSig );
    }
    if ( aExp == 0 ) {
        if ( (bits64) ( aSig0<<1 ) == 0 ) return a;
        normalizeFloatx80Subnormal( aSig0, &aExp, &aSig0 );
    }
    bSig |= LIT64( 0x8000000000000000 );
    zSign = aSign;
    expDiff = aExp - bExp;
    aSig1 = 0;
    if ( expDiff < 0 ) {
        if ( expDiff < -1 ) return a;
        shift128Right( aSig0, 0, 1, &aSig0, &aSig1 );
        expDiff = 0;
    }
    q = ( bSig <= aSig0 );
    if ( q ) aSig0 -= bSig;
    expDiff -= 64;
    while ( 0 < expDiff ) {
        q = estimateDiv128To64( aSig0, aSig1, bSig );
        q = ( 2 < q ) ? q - 2 : 0;
        mul64To128( bSig, q, &term0, &term1 );
        sub128( aSig0, aSig1, term0, term1, &aSig0, &aSig1 );
        shortShift128Left( aSig0, aSig1, 62, &aSig0, &aSig1 );
        expDiff -= 62;
    }
    expDiff += 64;
    if ( 0 < expDiff ) {
        q = estimateDiv128To64( aSig0, aSig1, bSig );
        q = ( 2 < q ) ? q - 2 : 0;
        q >>= 64 - expDiff;
        mul64To128( bSig, q<<( 64 - expDiff ), &term0, &term1 );
        sub128( aSig0, aSig1, term0, term1, &aSig0, &aSig1 );
        shortShift128Left( 0, bSig, 64 - expDiff, &term0, &term1 );
        while ( le128( term0, term1, aSig0, aSig1 ) ) {
            ++q;
            sub128( aSig0, aSig1, term0, term1, &aSig0, &aSig1 );
        }
    }
    else {
        term1 = 0;
        term0 = bSig;
    }
    sub128( term0, term1, aSig0, aSig1, &alternateASig0, &alternateASig1 );
    if (    lt128( alternateASig0, alternateASig1, aSig0, aSig1 )
         || (    eq128( alternateASig0, alternateASig1, aSig0, aSig1 )
              && ( q & 1 ) )
       ) {
        aSig0 = alternateASig0;
        aSig1 = alternateASig1;
        zSign = ! zSign;
    }

    return
        normalizeRoundAndPackFloatx80(
            roundData, zSign, bExp + expDiff, aSig0, aSig1 );

}