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// See LICENSE.SoftFloat for license details.
#include <stdbool.h>
#include <stdint.h>
#include "platform.h"
#include "primitives.h"
#include "internals.h"
#include "specialize.h"
#include "softfloat.h"
float64_t f64_sqrt( float64_t a )
{
union ui64_f64 uA;
uint_fast64_t uiA;
bool signA;
int_fast16_t expA;
uint_fast64_t sigA, uiZ;
struct exp16_sig64 normExpSig;
int_fast16_t expZ;
uint_fast32_t sigZ32;
uint_fast64_t sigZ;
struct uint128 term, rem;
union ui64_f64 uZ;
uA.f = a;
uiA = uA.ui;
signA = signF64UI( uiA );
expA = expF64UI( uiA );
sigA = fracF64UI( uiA );
if ( expA == 0x7FF ) {
if ( sigA ) {
uiZ = softfloat_propagateNaNF64UI( uiA, 0 );
goto uiZ;
}
if ( ! signA ) return a;
goto invalid;
}
if ( signA ) {
if ( ! ( expA | sigA ) ) return a;
goto invalid;
}
if ( ! expA ) {
if ( ! sigA ) return a;
normExpSig = softfloat_normSubnormalF64Sig( sigA );
expA = normExpSig.exp;
sigA = normExpSig.sig;
}
expZ = ( ( expA - 0x3FF )>>1 ) + 0x3FE;
sigA |= UINT64_C( 0x0010000000000000 );
sigZ32 = softfloat_estimateSqrt32( expA, sigA>>21 );
sigA <<= 9 - ( expA & 1 );
sigZ =
softfloat_estimateDiv128To64( sigA, 0, (uint_fast64_t) sigZ32<<32 )
+ ( (uint_fast64_t) sigZ32<<30 );
if ( ( sigZ & 0x1FF ) <= 5 ) {
term = softfloat_mul64To128( sigZ, sigZ );
rem = softfloat_sub128( sigA, 0, term.v64, term.v0 );
while ( UINT64_C( 0x8000000000000000 ) <= rem.v64 ) {
--sigZ;
rem =
softfloat_add128(
rem.v64, rem.v0, sigZ>>63, (uint64_t) ( sigZ<<1 ) );
}
sigZ |= ( ( rem.v64 | rem.v0 ) != 0 );
}
return softfloat_roundPackToF64( 0, expZ, sigZ );
invalid:
softfloat_raiseFlags( softfloat_flag_invalid );
uiZ = defaultNaNF64UI;
uiZ:
uZ.ui = uiZ;
return uZ.f;
}
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