Eyck Jentzsch
dcaf5467e8
(http://www.jhauser.us/arithmetic/SoftFloat.html) with RISCV specialization and cmake build
205 lines
7.8 KiB
C
205 lines
7.8 KiB
C
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/*============================================================================
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This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
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Package, Release 3e, by John R. Hauser.
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Copyright 2011, 2012, 2013, 2014 The Regents of the University of California.
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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1. Redistributions of source code must retain the above copyright notice,
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this list of conditions, and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions, and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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3. Neither the name of the University nor the names of its contributors may
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be used to endorse or promote products derived from this software without
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specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY
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EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE
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DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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=============================================================================*/
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#include <stdbool.h>
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#include <stdint.h>
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#include "platform.h"
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#include "internals.h"
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#include "specialize.h"
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#include "softfloat.h"
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#ifdef SOFTFLOAT_FAST_INT64
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void
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extF80M_rem(
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const extFloat80_t *aPtr, const extFloat80_t *bPtr, extFloat80_t *zPtr )
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{
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*zPtr = extF80_rem( *aPtr, *bPtr );
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}
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#else
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void
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extF80M_rem(
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const extFloat80_t *aPtr, const extFloat80_t *bPtr, extFloat80_t *zPtr )
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{
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const struct extFloat80M *aSPtr, *bSPtr;
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struct extFloat80M *zSPtr;
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uint_fast16_t uiA64;
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int32_t expA, expB;
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uint64_t x64;
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bool signRem;
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uint64_t sigA;
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int32_t expDiff;
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uint32_t rem[3], x[3], sig32B, q, recip32, rem2[3], *remPtr, *altRemPtr;
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uint32_t *newRemPtr, wordMeanRem;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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aSPtr = (const struct extFloat80M *) aPtr;
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bSPtr = (const struct extFloat80M *) bPtr;
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zSPtr = (struct extFloat80M *) zPtr;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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uiA64 = aSPtr->signExp;
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expA = expExtF80UI64( uiA64 );
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expB = expExtF80UI64( bSPtr->signExp );
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if ( (expA == 0x7FFF) || (expB == 0x7FFF) ) {
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if ( softfloat_tryPropagateNaNExtF80M( aSPtr, bSPtr, zSPtr ) ) return;
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if ( expA == 0x7FFF ) goto invalid;
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/*--------------------------------------------------------------------
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| If we get here, then argument b is an infinity and `expB' is 0x7FFF;
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| Doubling `expB' is an easy way to ensure that `expDiff' later is
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| less than -1, which will result in returning a canonicalized version
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| of argument a.
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*--------------------------------------------------------------------*/
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expB += expB;
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if ( ! expB ) expB = 1;
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x64 = bSPtr->signif;
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if ( ! (x64 & UINT64_C( 0x8000000000000000 )) ) {
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if ( ! x64 ) goto invalid;
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expB += softfloat_normExtF80SigM( &x64 );
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}
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signRem = signExtF80UI64( uiA64 );
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if ( ! expA ) expA = 1;
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sigA = aSPtr->signif;
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if ( ! (sigA & UINT64_C( 0x8000000000000000 )) ) {
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if ( ! sigA ) {
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expA = 0;
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goto copyA;
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}
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expA += softfloat_normExtF80SigM( &sigA );
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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expDiff = expA - expB;
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if ( expDiff < -1 ) goto copyA;
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rem[indexWord( 3, 2 )] = sigA>>34;
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rem[indexWord( 3, 1 )] = sigA>>2;
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rem[indexWord( 3, 0 )] = (uint32_t) sigA<<30;
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x[indexWord( 3, 0 )] = (uint32_t) x64<<30;
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sig32B = x64>>32;
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x64 >>= 2;
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x[indexWord( 3, 2 )] = x64>>32;
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x[indexWord( 3, 1 )] = x64;
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if ( expDiff < 1 ) {
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if ( expDiff ) {
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--expB;
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softfloat_add96M( x, x, x );
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q = 0;
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} else {
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q = (softfloat_compare96M( x, rem ) <= 0);
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if ( q ) softfloat_sub96M( rem, x, rem );
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}
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} else {
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recip32 = softfloat_approxRecip32_1( sig32B );
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expDiff -= 30;
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for (;;) {
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x64 = (uint64_t) rem[indexWordHi( 3 )] * recip32;
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if ( expDiff < 0 ) break;
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q = (x64 + 0x80000000)>>32;
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softfloat_remStep96MBy32( rem, 29, x, q, rem );
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if ( rem[indexWordHi( 3 )] & 0x80000000 ) {
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softfloat_add96M( rem, x, rem );
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}
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expDiff -= 29;
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}
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/*--------------------------------------------------------------------
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| (`expDiff' cannot be less than -29 here.)
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*--------------------------------------------------------------------*/
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q = (uint32_t) (x64>>32)>>(~expDiff & 31);
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softfloat_remStep96MBy32( rem, expDiff + 30, x, q, rem );
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if ( rem[indexWordHi( 3 )] & 0x80000000 ) {
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remPtr = rem;
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altRemPtr = rem2;
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softfloat_add96M( remPtr, x, altRemPtr );
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goto selectRem;
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}
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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remPtr = rem;
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altRemPtr = rem2;
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do {
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++q;
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newRemPtr = altRemPtr;
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softfloat_sub96M( remPtr, x, newRemPtr );
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altRemPtr = remPtr;
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remPtr = newRemPtr;
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} while ( ! (remPtr[indexWordHi( 3 )] & 0x80000000) );
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selectRem:
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softfloat_add96M( remPtr, altRemPtr, x );
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wordMeanRem = x[indexWordHi( 3 )];
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if (
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(wordMeanRem & 0x80000000)
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|| (! wordMeanRem && (q & 1) && ! x[indexWord( 3, 0 )]
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&& ! x[indexWord( 3, 1 )])
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) {
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remPtr = altRemPtr;
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}
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if ( remPtr[indexWordHi( 3 )] & 0x80000000 ) {
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signRem = ! signRem;
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softfloat_negX96M( remPtr );
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}
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softfloat_normRoundPackMToExtF80M( signRem, expB + 2, remPtr, 80, zSPtr );
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return;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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invalid:
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softfloat_invalidExtF80M( zSPtr );
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return;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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copyA:
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if ( expA < 1 ) {
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sigA >>= 1 - expA;
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expA = 0;
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}
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zSPtr->signExp = packToExtF80UI64( signRem, expA );
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zSPtr->signif = sigA;
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}
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#endif
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