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148 lines
5.5 KiB
C
148 lines
5.5 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 3c, by John R. Hauser.
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Copyright 2011, 2012, 2013, 2014, 2017 The Regents of the University of
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California. 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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extFloat80_t
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extF80_roundToInt( extFloat80_t a, uint_fast8_t roundingMode, bool exact )
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{
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union { struct extFloat80M s; extFloat80_t f; } uA;
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uint_fast16_t uiA64, signUI64;
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int_fast32_t exp;
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uint_fast64_t sigA;
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uint_fast16_t uiZ64;
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uint_fast64_t sigZ;
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struct exp32_sig64 normExpSig;
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struct uint128 uiZ;
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uint_fast64_t lastBitMask, roundBitsMask;
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union { struct extFloat80M s; extFloat80_t f; } uZ;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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uA.f = a;
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uiA64 = uA.s.signExp;
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signUI64 = uiA64 & packToExtF80UI64( 1, 0 );
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exp = expExtF80UI64( uiA64 );
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sigA = uA.s.signif;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if ( ! (sigA & UINT64_C( 0x8000000000000000 )) && (exp != 0x7FFF) ) {
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if ( ! sigA ) {
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uiZ64 = signUI64;
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sigZ = 0;
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goto uiZ;
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}
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normExpSig = softfloat_normSubnormalExtF80Sig( sigA );
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exp += normExpSig.exp;
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sigA = normExpSig.sig;
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if ( 0x403E <= exp ) {
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if ( exp == 0x7FFF ) {
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if ( sigA & UINT64_C( 0x7FFFFFFFFFFFFFFF ) ) {
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uiZ = softfloat_propagateNaNExtF80UI( uiA64, sigA, 0, 0 );
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uiZ64 = uiZ.v64;
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sigZ = uiZ.v0;
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goto uiZ;
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}
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sigZ = UINT64_C( 0x8000000000000000 );
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} else {
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sigZ = sigA;
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}
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uiZ64 = signUI64 | exp;
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goto uiZ;
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}
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if ( exp <= 0x3FFE ) {
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if ( exact ) softfloat_exceptionFlags |= softfloat_flag_inexact;
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switch ( roundingMode ) {
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case softfloat_round_near_even:
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if ( ! (sigA & UINT64_C( 0x7FFFFFFFFFFFFFFF )) ) break;
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case softfloat_round_near_maxMag:
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if ( exp == 0x3FFE ) goto mag1;
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break;
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case softfloat_round_min:
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if ( signUI64 ) goto mag1;
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break;
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case softfloat_round_max:
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if ( ! signUI64 ) goto mag1;
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break;
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}
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uiZ64 = signUI64;
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sigZ = 0;
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goto uiZ;
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mag1:
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uiZ64 = signUI64 | 0x3FFF;
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sigZ = UINT64_C( 0x8000000000000000 );
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goto uiZ;
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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uiZ64 = signUI64 | exp;
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lastBitMask = (uint_fast64_t) 1<<(0x403E - exp);
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roundBitsMask = lastBitMask - 1;
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sigZ = sigA;
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if ( roundingMode == softfloat_round_near_maxMag ) {
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sigZ += lastBitMask>>1;
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} else if ( roundingMode == softfloat_round_near_even ) {
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sigZ += lastBitMask>>1;
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if ( ! (sigZ & roundBitsMask) ) sigZ &= ~lastBitMask;
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} else if (
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roundingMode == (signUI64 ? softfloat_round_min : softfloat_round_max)
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) {
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sigZ += roundBitsMask;
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}
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sigZ &= ~roundBitsMask;
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if ( ! sigZ ) {
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++uiZ64;
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sigZ = UINT64_C( 0x8000000000000000 );
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}
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if ( exact && (sigZ != sigA) ) {
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softfloat_exceptionFlags |= softfloat_flag_inexact;
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}
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uiZ:
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uZ.s.signExp = uiZ64;
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uZ.s.signif = sigZ;
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return uZ.f;
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}
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