mirror of
https://github.com/ilyakooo0/urbit.git
synced 2024-12-25 07:52:59 +03:00
131 lines
5.1 KiB
C
131 lines
5.1 KiB
C
|
|
/*============================================================================
|
|
|
|
This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
|
|
Package, Release 3, by John R. Hauser.
|
|
|
|
Copyright 2011, 2012, 2013, 2014 The Regents of the University of California
|
|
(Regents). 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 two paragraphs of disclaimer.
|
|
Redistributions in binary form must reproduce the above copyright notice,
|
|
this list of conditions, and the following two paragraphs of disclaimer in the
|
|
documentation and/or other materials provided with the distribution. Neither
|
|
the name of the Regents nor the names of its contributors may be used to
|
|
endorse or promote products derived from this software without specific prior
|
|
written permission.
|
|
|
|
IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
|
|
SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING
|
|
OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF REGENTS HAS
|
|
BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
|
|
REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED
|
|
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
PURPOSE. THE SOFTWARE AND ACCOMPANYING DOCUMENTATION, IF ANY, PROVIDED
|
|
HEREUNDER IS PROVIDED "AS IS". REGENTS HAS NO OBLIGATION TO PROVIDE
|
|
MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
|
|
|
|
=============================================================================*/
|
|
|
|
#include <stdbool.h>
|
|
#include <stdint.h>
|
|
#include "platform.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;
|
|
uint32_t sig32A, recipSqrt32, sig32Z;
|
|
uint_fast64_t rem;
|
|
uint32_t q;
|
|
uint_fast64_t sigZ, shiftedSigZ;
|
|
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;
|
|
}
|
|
/*------------------------------------------------------------------------
|
|
| (`sig32Z' is guaranteed to be a lower bound on the square root of
|
|
| `sig32A', which makes `sig32Z' also a lower bound on the square root of
|
|
| `sigA'.)
|
|
*------------------------------------------------------------------------*/
|
|
expZ = ((expA - 0x3FF)>>1) + 0x3FE;
|
|
expA &= 1;
|
|
sigA |= UINT64_C( 0x0010000000000000 );
|
|
sig32A = sigA>>21;
|
|
recipSqrt32 = softfloat_approxRecipSqrt32_1( expA, sig32A );
|
|
sig32Z = ((uint_fast64_t) sig32A * recipSqrt32)>>32;
|
|
if ( expA ) {
|
|
sigA <<= 8;
|
|
sig32Z >>= 1;
|
|
} else {
|
|
sigA <<= 9;
|
|
}
|
|
rem = sigA - (uint_fast64_t) sig32Z * sig32Z;
|
|
q = ((uint32_t) (rem>>2) * (uint_fast64_t) recipSqrt32)>>32;
|
|
sigZ = ((uint_fast64_t) sig32Z<<32 | 1<<5) + ((uint_fast64_t) q<<3);
|
|
/*------------------------------------------------------------------------
|
|
*------------------------------------------------------------------------*/
|
|
if ( (sigZ & 0x1FF) < 1<<5 ) {
|
|
sigZ &= ~(uint_fast64_t) 0x3F;
|
|
shiftedSigZ = sigZ>>6;
|
|
rem = (sigA<<52) - shiftedSigZ * shiftedSigZ;
|
|
if ( rem & UINT64_C( 0x8000000000000000 ) ) {
|
|
--sigZ;
|
|
} else {
|
|
if ( rem ) sigZ |= 1;
|
|
}
|
|
}
|
|
return softfloat_roundPackToF64( 0, expZ, sigZ );
|
|
/*------------------------------------------------------------------------
|
|
*------------------------------------------------------------------------*/
|
|
invalid:
|
|
softfloat_raiseFlags( softfloat_flag_invalid );
|
|
uiZ = defaultNaNF64UI;
|
|
uiZ:
|
|
uZ.ui = uiZ;
|
|
return uZ.f;
|
|
|
|
}
|
|
|