173 lines
7.0 KiB
C
173 lines
7.0 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, 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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float128_t
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f128_roundToInt( float128_t a, uint_fast8_t roundingMode, bool exact )
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{
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union ui128_f128 uA;
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uint_fast64_t uiA64, uiA0;
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int_fast32_t exp;
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struct uint128 uiZ;
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uint_fast64_t lastBitMask0, roundBitsMask;
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bool roundNearEven;
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uint_fast64_t lastBitMask64;
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union ui128_f128 uZ;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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uA.f = a;
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uiA64 = uA.ui.v64;
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uiA0 = uA.ui.v0;
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exp = expF128UI64( uiA64 );
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if ( 0x402F <= exp ) {
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/*--------------------------------------------------------------------
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*--------------------------------------------------------------------*/
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if ( 0x406F <= exp ) {
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if ( (exp == 0x7FFF) && (fracF128UI64( uiA64 ) | uiA0) ) {
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uiZ = softfloat_propagateNaNF128UI( uiA64, uiA0, 0, 0 );
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goto uiZ;
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}
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return a;
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}
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/*--------------------------------------------------------------------
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*--------------------------------------------------------------------*/
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lastBitMask0 = (uint_fast64_t) 2<<(0x406E - exp);
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roundBitsMask = lastBitMask0 - 1;
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uiZ.v64 = uiA64;
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uiZ.v0 = uiA0;
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roundNearEven = (roundingMode == softfloat_round_near_even);
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if ( roundNearEven || (roundingMode == softfloat_round_near_maxMag) ) {
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if ( exp == 0x402F ) {
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if ( UINT64_C( 0x8000000000000000 ) <= uiZ.v0 ) {
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++uiZ.v64;
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if (
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roundNearEven
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&& (uiZ.v0 == UINT64_C( 0x8000000000000000 ))
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) {
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uiZ.v64 &= ~1;
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}
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}
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} else {
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uiZ = softfloat_add128( uiZ.v64, uiZ.v0, 0, lastBitMask0>>1 );
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if ( roundNearEven && !(uiZ.v0 & roundBitsMask) ) {
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uiZ.v0 &= ~lastBitMask0;
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}
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}
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} else if (
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roundingMode
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== (signF128UI64( uiZ.v64 ) ? softfloat_round_min
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: softfloat_round_max)
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) {
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uiZ = softfloat_add128( uiZ.v64, uiZ.v0, 0, roundBitsMask );
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}
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uiZ.v0 &= ~roundBitsMask;
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lastBitMask64 = !lastBitMask0;
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} else {
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/*--------------------------------------------------------------------
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*--------------------------------------------------------------------*/
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if ( exp < 0x3FFF ) {
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if ( !((uiA64 & UINT64_C( 0x7FFFFFFFFFFFFFFF )) | uiA0) ) return a;
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if ( exact ) softfloat_exceptionFlags |= softfloat_flag_inexact;
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uiZ.v64 = uiA64 & packToF128UI64( 1, 0, 0 );
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uiZ.v0 = 0;
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switch ( roundingMode ) {
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case softfloat_round_near_even:
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if ( !(fracF128UI64( uiA64 ) | uiA0) ) break;
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case softfloat_round_near_maxMag:
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if ( exp == 0x3FFE ) uiZ.v64 |= packToF128UI64( 0, 0x3FFF, 0 );
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break;
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case softfloat_round_min:
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if ( uiZ.v64 ) uiZ.v64 = packToF128UI64( 1, 0x3FFF, 0 );
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break;
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case softfloat_round_max:
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if ( !uiZ.v64 ) uiZ.v64 = packToF128UI64( 0, 0x3FFF, 0 );
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break;
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#ifdef SOFTFLOAT_ROUND_ODD
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case softfloat_round_odd:
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uiZ.v64 |= packToF128UI64( 0, 0x3FFF, 0 );
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break;
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#endif
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}
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goto uiZ;
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}
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/*--------------------------------------------------------------------
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*--------------------------------------------------------------------*/
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uiZ.v64 = uiA64;
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uiZ.v0 = 0;
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lastBitMask64 = (uint_fast64_t) 1<<(0x402F - exp);
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roundBitsMask = lastBitMask64 - 1;
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if ( roundingMode == softfloat_round_near_maxMag ) {
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uiZ.v64 += lastBitMask64>>1;
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} else if ( roundingMode == softfloat_round_near_even ) {
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uiZ.v64 += lastBitMask64>>1;
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if ( !((uiZ.v64 & roundBitsMask) | uiA0) ) {
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uiZ.v64 &= ~lastBitMask64;
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}
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} else if (
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roundingMode
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== (signF128UI64( uiZ.v64 ) ? softfloat_round_min
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: softfloat_round_max)
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) {
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uiZ.v64 = (uiZ.v64 | (uiA0 != 0)) + roundBitsMask;
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}
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uiZ.v64 &= ~roundBitsMask;
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lastBitMask0 = 0;
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}
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if ( (uiZ.v64 != uiA64) || (uiZ.v0 != uiA0) ) {
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#ifdef SOFTFLOAT_ROUND_ODD
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if ( roundingMode == softfloat_round_odd ) {
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uiZ.v64 |= lastBitMask64;
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uiZ.v0 |= lastBitMask0;
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}
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#endif
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if ( exact ) softfloat_exceptionFlags |= softfloat_flag_inexact;
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}
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uiZ:
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uZ.ui = uiZ;
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return uZ.f;
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}
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