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113 lines
4.5 KiB
C
113 lines
4.5 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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float64_t f64_roundToInt( float64_t a, uint_fast8_t roundingMode, bool exact )
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{
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union ui64_f64 uA;
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uint_fast64_t uiA;
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int_fast16_t exp;
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uint_fast64_t uiZ, lastBitMask, roundBitsMask;
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union ui64_f64 uZ;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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uA.f = a;
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uiA = uA.ui;
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exp = expF64UI( uiA );
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if ( exp <= 0x3FE ) {
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if ( ! (uiA & UINT64_C( 0x7FFFFFFFFFFFFFFF )) ) return a;
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if ( exact ) softfloat_exceptionFlags |= softfloat_flag_inexact;
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uiZ = uiA & packToF64UI( 1, 0, 0 );
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switch ( roundingMode ) {
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case softfloat_round_near_even:
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if ( ! fracF64UI( uiA ) ) break;
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case softfloat_round_near_maxMag:
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if ( exp == 0x3FE ) uiZ |= packToF64UI( 0, 0x3FF, 0 );
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break;
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case softfloat_round_min:
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if ( uiZ ) uiZ = packToF64UI( 1, 0x3FF, 0 );
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break;
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case softfloat_round_max:
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if ( ! uiZ ) uiZ = packToF64UI( 0, 0x3FF, 0 );
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break;
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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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if ( 0x433 <= exp ) {
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if ( (exp == 0x7FF) && fracF64UI( uiA ) ) {
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uiZ = softfloat_propagateNaNF64UI( uiA, 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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uiZ = uiA;
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lastBitMask = (uint_fast64_t) 1<<(0x433 - exp);
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roundBitsMask = lastBitMask - 1;
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if ( roundingMode == softfloat_round_near_maxMag ) {
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uiZ += lastBitMask>>1;
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} else if ( roundingMode == softfloat_round_near_even ) {
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uiZ += lastBitMask>>1;
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if ( ! (uiZ & roundBitsMask) ) uiZ &= ~lastBitMask;
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} else if (
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roundingMode
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== (signF64UI( uiZ ) ? softfloat_round_min : softfloat_round_max)
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) {
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uiZ += roundBitsMask;
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}
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uiZ &= ~roundBitsMask;
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if ( exact && (uiZ != uiA) ) {
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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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