140 lines
4.8 KiB
C
140 lines
4.8 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, 2015 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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softfloat_subMagsF128(
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uint_fast64_t uiA64,
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uint_fast64_t uiA0,
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uint_fast64_t uiB64,
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uint_fast64_t uiB0,
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bool signZ
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)
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{
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int_fast32_t expA;
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struct uint128 sigA;
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int_fast32_t expB;
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struct uint128 sigB, sigZ;
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int_fast32_t expDiff, expZ;
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struct uint128 uiZ;
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union ui128_f128 uZ;
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expA = expF128UI64( uiA64 );
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sigA.v64 = fracF128UI64( uiA64 );
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sigA.v0 = uiA0;
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expB = expF128UI64( uiB64 );
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sigB.v64 = fracF128UI64( uiB64 );
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sigB.v0 = uiB0;
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sigA = softfloat_shortShiftLeft128( sigA.v64, sigA.v0, 4 );
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sigB = softfloat_shortShiftLeft128( sigB.v64, sigB.v0, 4 );
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expDiff = expA - expB;
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if ( 0 < expDiff ) goto expABigger;
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if ( expDiff < 0 ) goto expBBigger;
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if ( expA == 0x7FFF ) {
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if ( sigA.v64 | sigA.v0 | sigB.v64 | sigB.v0 ) goto propagateNaN;
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softfloat_raiseFlags( softfloat_flag_invalid );
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uiZ.v64 = defaultNaNF128UI64;
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uiZ.v0 = defaultNaNF128UI0;
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goto uiZ;
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}
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expZ = expA;
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if ( ! expZ ) expZ = 1;
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if ( sigB.v64 < sigA.v64 ) goto aBigger;
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if ( sigA.v64 < sigB.v64 ) goto bBigger;
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if ( sigB.v0 < sigA.v0 ) goto aBigger;
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if ( sigA.v0 < sigB.v0 ) goto bBigger;
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uiZ.v64 =
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packToF128UI64(
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(softfloat_roundingMode == softfloat_round_min), 0, 0 );
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uiZ.v0 = 0;
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goto uiZ;
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expBBigger:
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if ( expB == 0x7FFF ) {
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if ( sigB.v64 | sigB.v0 ) goto propagateNaN;
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uiZ.v64 = packToF128UI64( signZ ^ 1, 0x7FFF, 0 );
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uiZ.v0 = 0;
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goto uiZ;
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}
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if ( expA ) {
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sigA.v64 |= UINT64_C( 0x0010000000000000 );
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} else {
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++expDiff;
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if ( ! expDiff ) goto newlyAlignedBBigger;
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}
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sigA = softfloat_shiftRightJam128( sigA.v64, sigA.v0, -expDiff );
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newlyAlignedBBigger:
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expZ = expB;
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sigB.v64 |= UINT64_C( 0x0010000000000000 );
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bBigger:
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signZ = ! signZ;
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sigZ = softfloat_sub128( sigB.v64, sigB.v0, sigA.v64, sigA.v0 );
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goto normRoundPack;
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expABigger:
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if ( expA == 0x7FFF ) {
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if ( sigA.v64 | sigA.v0 ) goto propagateNaN;
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uiZ.v64 = uiA64;
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uiZ.v0 = uiA0;
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goto uiZ;
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}
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if ( expB ) {
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sigB.v64 |= UINT64_C( 0x0010000000000000 );
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} else {
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--expDiff;
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if ( ! expDiff ) goto newlyAlignedABigger;
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}
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sigB = softfloat_shiftRightJam128( sigB.v64, sigB.v0, expDiff );
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newlyAlignedABigger:
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expZ = expA;
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sigA.v64 |= UINT64_C( 0x0010000000000000 );
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aBigger:
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sigZ = softfloat_sub128( sigA.v64, sigA.v0, sigB.v64, sigB.v0 );
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normRoundPack:
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return softfloat_normRoundPackToF128( signZ, expZ - 5, sigZ.v64, sigZ.v0 );
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propagateNaN:
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uiZ = softfloat_propagateNaNF128UI( uiA64, uiA0, uiB64, uiB0 );
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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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