f128_rem.c File Reference

#include <stdbool.h>
#include <stdint.h>
#include "platform.h"
#include "internals.h"
#include "specialize.h"
#include "softfloat.h"

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Functions
float128_t	f128_rem (float128_t a, float128_t b)

Function Documentation

f128_rem()

float128_t f128_rem	(	float128_t	a,
		float128_t	b )

Definition at line 44 of file f128_rem.c.

{
    union ui128_f128 uA;
    uint_fast64_t uiA64, uiA0;
    bool signA;
    int_fast32_t expA;
    struct uint128 sigA;
    union ui128_f128 uB;
    uint_fast64_t uiB64, uiB0;
    int_fast32_t expB;
    struct uint128 sigB;
    struct exp32_sig128 normExpSig;
    struct uint128 rem;
    int_fast32_t expDiff;
    uint_fast32_t q, recip32;
    uint_fast64_t q64;
    struct uint128 term, altRem, meanRem;
    bool signRem;
    struct uint128 uiZ;
    union ui128_f128 uZ;
 
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
    uA.f = a;
    uiA64 = uA.ui.v64;
    uiA0  = uA.ui.v0;
    signA = signF128UI64( uiA64 );
    expA  = expF128UI64( uiA64 );
    sigA.v64 = fracF128UI64( uiA64 );
    sigA.v0  = uiA0;
    uB.f = b;
    uiB64 = uB.ui.v64;
    uiB0  = uB.ui.v0;
    expB  = expF128UI64( uiB64 );
    sigB.v64 = fracF128UI64( uiB64 );
    sigB.v0  = uiB0;
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
    if ( expA == 0x7FFF ) {
        if (
            (sigA.v64 | sigA.v0) || ((expB == 0x7FFF) && (sigB.v64 | sigB.v0))
        ) {
            goto propagateNaN;
        }
        goto invalid;
    }
    if ( expB == 0x7FFF ) {
        if ( sigB.v64 | sigB.v0 ) goto propagateNaN;
        return a;
    }
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
    if ( ! expB ) {
        if ( ! (sigB.v64 | sigB.v0) ) goto invalid;
        normExpSig = softfloat_normSubnormalF128Sig( sigB.v64, sigB.v0 );
        expB = normExpSig.exp;
        sigB = normExpSig.sig;
    }
    if ( ! expA ) {
        if ( ! (sigA.v64 | sigA.v0) ) return a;
        normExpSig = softfloat_normSubnormalF128Sig( sigA.v64, sigA.v0 );
        expA = normExpSig.exp;
        sigA = normExpSig.sig;
    }
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
    sigA.v64 |= UINT64_C( 0x0001000000000000 );
    sigB.v64 |= UINT64_C( 0x0001000000000000 );
    rem = sigA;
    expDiff = expA - expB;
    if ( expDiff < 1 ) {
        if ( expDiff < -1 ) return a;
        if ( expDiff ) {
            --expB;
            sigB = softfloat_add128( sigB.v64, sigB.v0, sigB.v64, sigB.v0 );
            q = 0;
        } else {
            q = softfloat_le128( sigB.v64, sigB.v0, rem.v64, rem.v0 );
            if ( q ) {
                rem = softfloat_sub128( rem.v64, rem.v0, sigB.v64, sigB.v0 );
            }
        }
    } else {
        recip32 = softfloat_approxRecip32_1( sigB.v64>>17 );
        expDiff -= 30;
        for (;;) {
            q64 = (uint_fast64_t) (uint32_t) (rem.v64>>19) * recip32;
            if ( expDiff < 0 ) break;
            q = (q64 + 0x80000000)>>32;
            rem = softfloat_shortShiftLeft128( rem.v64, rem.v0, 29 );
            term = softfloat_mul128By32( sigB.v64, sigB.v0, q );
            rem = softfloat_sub128( rem.v64, rem.v0, term.v64, term.v0 );
            if ( rem.v64 & UINT64_C( 0x8000000000000000 ) ) {
                rem = softfloat_add128( rem.v64, rem.v0, sigB.v64, sigB.v0 );
            }
            expDiff -= 29;
        }
        /*--------------------------------------------------------------------
        | (`expDiff' cannot be less than -29 here.)
        *--------------------------------------------------------------------*/
        q = (uint32_t) (q64>>32)>>(~expDiff & 31);
        rem = softfloat_shortShiftLeft128( rem.v64, rem.v0, expDiff + 30 );
        term = softfloat_mul128By32( sigB.v64, sigB.v0, q );
        rem = softfloat_sub128( rem.v64, rem.v0, term.v64, term.v0 );
        if ( rem.v64 & UINT64_C( 0x8000000000000000 ) ) {
            altRem = softfloat_add128( rem.v64, rem.v0, sigB.v64, sigB.v0 );
            goto selectRem;
        }
    }
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
    do {
        altRem = rem;
        ++q;
        rem = softfloat_sub128( rem.v64, rem.v0, sigB.v64, sigB.v0 );
    } while ( ! (rem.v64 & UINT64_C( 0x8000000000000000 )) );
 selectRem:
    meanRem = softfloat_add128( rem.v64, rem.v0, altRem.v64, altRem.v0 );
    if (
        (meanRem.v64 & UINT64_C( 0x8000000000000000 ))
            || (! (meanRem.v64 | meanRem.v0) && (q & 1))
    ) {
        rem = altRem;
    }
    signRem = signA;
    if ( rem.v64 & UINT64_C( 0x8000000000000000 ) ) {
        signRem = ! signRem;
        rem = softfloat_sub128( 0, 0, rem.v64, rem.v0 );
    }
    return softfloat_normRoundPackToF128( signRem, expB - 1, rem.v64, rem.v0 );
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
 propagateNaN:
    uiZ = softfloat_propagateNaNF128UI( uiA64, uiA0, uiB64, uiB0 );
    goto uiZ;
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
 invalid:
    softfloat_raiseFlags( softfloat_flag_invalid );
    uiZ.v64 = defaultNaNF128UI64;
    uiZ.v0  = defaultNaNF128UI0;
 uiZ:
    uZ.ui = uiZ;
    return uZ.f;
 
}

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