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https://github.com/openhwgroup/cvw
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118 lines
4.9 KiB
C
118 lines
4.9 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, 2015, 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 "softfloat.h"
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float64_t
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softfloat_roundPackToF64( bool sign, int_fast16_t exp, uint_fast64_t sig )
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{
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uint_fast8_t roundingMode;
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bool roundNearEven;
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uint_fast16_t roundIncrement, roundBits;
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bool isTiny;
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uint_fast64_t uiZ;
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union ui64_f64 uZ;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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roundingMode = softfloat_roundingMode;
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roundNearEven = (roundingMode == softfloat_round_near_even);
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roundIncrement = 0x200;
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if ( ! roundNearEven && (roundingMode != softfloat_round_near_maxMag) ) {
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roundIncrement =
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(roundingMode
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== (sign ? softfloat_round_min : softfloat_round_max))
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? 0x3FF
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: 0;
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}
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roundBits = sig & 0x3FF;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if ( 0x7FD <= (uint16_t) exp ) {
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if ( exp < 0 ) {
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/*----------------------------------------------------------------
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*----------------------------------------------------------------*/
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isTiny =
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(softfloat_detectTininess == softfloat_tininess_beforeRounding)
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|| (exp < -1)
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|| (sig + roundIncrement < UINT64_C( 0x8000000000000000 ));
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sig = softfloat_shiftRightJam64( sig, -exp );
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exp = 0;
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roundBits = sig & 0x3FF;
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if ( isTiny && roundBits ) {
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softfloat_raiseFlags( softfloat_flag_underflow );
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}
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} else if (
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(0x7FD < exp)
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|| (UINT64_C( 0x8000000000000000 ) <= sig + roundIncrement)
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) {
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/*----------------------------------------------------------------
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*----------------------------------------------------------------*/
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softfloat_raiseFlags(
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softfloat_flag_overflow | softfloat_flag_inexact );
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uiZ = packToF64UI( sign, 0x7FF, 0 ) - ! roundIncrement;
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goto uiZ;
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}
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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sig = (sig + roundIncrement)>>10;
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if ( roundBits ) {
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softfloat_exceptionFlags |= softfloat_flag_inexact;
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#ifdef SOFTFLOAT_ROUND_ODD
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if ( roundingMode == softfloat_round_odd ) {
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sig |= 1;
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goto packReturn;
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}
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#endif
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}
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sig &= ~(uint_fast64_t) (! (roundBits ^ 0x200) & roundNearEven);
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if ( ! sig ) exp = 0;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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packReturn:
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uiZ = packToF64UI( sign, exp, sig );
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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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