extF80M_sqrt.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
void	extF80M_sqrt (const extFloat80_t *aPtr, extFloat80_t *zPtr)

Function Documentation

extF80M_sqrt()

void extF80M_sqrt	(	const extFloat80_t *	aPtr,
		extFloat80_t *	zPtr )

Definition at line 55 of file extF80M_sqrt.c.

{
    const struct extFloat80M *aSPtr;
    struct extFloat80M *zSPtr;
    uint_fast16_t uiA64, signUI64;
    int32_t expA;
    uint64_t rem64;
    int32_t expZ;
    uint32_t rem96[3], sig32A, recipSqrt32, sig32Z, q;
    uint64_t sig64Z, x64;
    uint32_t rem32, term[4], rem[4], extSigZ[3];
 
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
    aSPtr = (const struct extFloat80M *) aPtr;
    zSPtr = (struct extFloat80M *) zPtr;
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
    uiA64 = aSPtr->signExp;
    signUI64 = uiA64 & packToExtF80UI64( 1, 0 );
    expA = expExtF80UI64( uiA64 );
    rem64 = aSPtr->signif;
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
    if ( expA == 0x7FFF ) {
        if ( rem64 & UINT64_C( 0x7FFFFFFFFFFFFFFF ) ) {
            softfloat_propagateNaNExtF80M( aSPtr, 0, zSPtr );
            return;
        }
        if ( signUI64 ) goto invalid;
        rem64 = UINT64_C( 0x8000000000000000 );
        goto copyA;
    }
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
    if ( ! expA ) expA = 1;
    if ( ! (rem64 & UINT64_C( 0x8000000000000000 )) ) {
        if ( ! rem64 ) {
            uiA64 = signUI64;
            goto copyA;
        }
        expA += softfloat_normExtF80SigM( &rem64 );
    }
    if ( signUI64 ) goto invalid;
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
    expZ = ((expA - 0x3FFF)>>1) + 0x3FFF;
    expA &= 1;
    softfloat_shortShiftLeft64To96M( rem64, 30 - expA, rem96 );
    sig32A = rem64>>32;
    recipSqrt32 = softfloat_approxRecipSqrt32_1( expA, sig32A );
    sig32Z = ((uint64_t) sig32A * recipSqrt32)>>32;
    if ( expA ) sig32Z >>= 1;
    rem64 =
        ((uint64_t) rem96[indexWord( 3, 2 )]<<32 | rem96[indexWord( 3, 1 )])
            - (uint64_t) sig32Z * sig32Z;
    rem96[indexWord( 3, 2 )] = rem64>>32;
    rem96[indexWord( 3, 1 )] = rem64;
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
    q = ((uint32_t) (rem64>>2) * (uint64_t) recipSqrt32)>>32;
    sig64Z = ((uint64_t) sig32Z<<32) + ((uint64_t) q<<3);
    term[indexWord( 3, 2 )] = 0;
    /*------------------------------------------------------------------------
    | (Repeating this loop is a rare occurrence.)
    *------------------------------------------------------------------------*/
    for (;;) {
        x64 = ((uint64_t) sig32Z<<32) + sig64Z;
        term[indexWord( 3, 1 )] = x64>>32;
        term[indexWord( 3, 0 )] = x64;
        softfloat_remStep96MBy32(
            rem96, 29, term, q, &rem[indexMultiwordHi( 4, 3 )] );
        rem32 = rem[indexWord( 4, 3 )];
        if ( ! (rem32 & 0x80000000) ) break;
        --q;
        sig64Z -= 1<<3;
    }
    rem64 = (uint64_t) rem32<<32 | rem[indexWord( 4, 2 )];
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
    q = (((uint32_t) (rem64>>2) * (uint64_t) recipSqrt32)>>32) + 2;
    if ( rem64>>34 ) q += recipSqrt32;
    x64 = (uint64_t) q<<7;
    extSigZ[indexWord( 3, 0 )] = x64;
    x64 = (sig64Z<<1) + (x64>>32);
    extSigZ[indexWord( 3, 2 )] = x64>>32;
    extSigZ[indexWord( 3, 1 )] = x64;
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
    if ( (q & 0xFFFFFF) <= 2 ) {
        q &= ~(uint32_t) 0xFFFF;
        extSigZ[indexWordLo( 3 )] = q<<7;
        x64 = sig64Z + (q>>27);
        term[indexWord( 4, 3 )] = 0;
        term[indexWord( 4, 2 )] = x64>>32;
        term[indexWord( 4, 1 )] = x64;
        term[indexWord( 4, 0 )] = q<<5;
        rem[indexWord( 4, 0 )] = 0;
        softfloat_remStep128MBy32( rem, 28, term, q, rem );
        q = rem[indexWordHi( 4 )];
        if ( q & 0x80000000 ) {
            softfloat_sub1X96M( extSigZ );
        } else {
            if ( q || rem[indexWord( 4, 1 )] || rem[indexWord( 4, 2 )] ) {
                extSigZ[indexWordLo( 3 )] |= 1;
            }
        }
    }
    softfloat_roundPackMToExtF80M(
        0, expZ, extSigZ, extF80_roundingPrecision, zSPtr );
    return;
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
 invalid:
    softfloat_invalidExtF80M( zSPtr );
    return;
    /*------------------------------------------------------------------------
    *------------------------------------------------------------------------*/
 copyA:
    zSPtr->signExp = uiA64;
    zSPtr->signif  = rem64;
 
}

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