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113 lines
3.7 KiB
C
113 lines
3.7 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 3, by John R. Hauser.
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Copyright 2011, 2012, 2013, 2014 The Regents of the University of California
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(Regents). All Rights Reserved. Redistribution and use in source and binary
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forms, with or without modification, are permitted provided that the following
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conditions are met:
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Redistributions of source code must retain the above copyright notice,
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this list of conditions, and the following two paragraphs of disclaimer.
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Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions, and the following two paragraphs of disclaimer in the
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documentation and/or other materials provided with the distribution. Neither
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the name of the Regents nor the names of its contributors may be used to
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endorse or promote products derived from this software without specific prior
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written permission.
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IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
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SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING
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OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF REGENTS HAS
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BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED
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TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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PURPOSE. THE SOFTWARE AND ACCOMPANYING DOCUMENTATION, IF ANY, PROVIDED
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HEREUNDER IS PROVIDED "AS IS". REGENTS HAS NO OBLIGATION TO PROVIDE
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MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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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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float32_t
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softfloat_subMagsF32( uint_fast32_t uiA, uint_fast32_t uiB, bool signZ )
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{
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int_fast16_t expA;
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uint_fast32_t sigA;
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int_fast16_t expB;
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uint_fast32_t sigB;
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int_fast16_t expDiff;
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uint_fast32_t uiZ;
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int_fast16_t expZ;
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uint_fast32_t sigZ;
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union ui32_f32 uZ;
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expA = expF32UI( uiA );
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sigA = fracF32UI( uiA );
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expB = expF32UI( uiB );
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sigB = fracF32UI( uiB );
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expDiff = expA - expB;
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sigA <<= 7;
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sigB <<= 7;
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if ( 0 < expDiff ) goto expABigger;
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if ( expDiff < 0 ) goto expBBigger;
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if ( expA == 0xFF ) {
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if ( sigA | sigB ) goto propagateNaN;
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softfloat_raiseFlags( softfloat_flag_invalid );
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uiZ = defaultNaNF32UI;
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goto uiZ;
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}
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if ( ! expA ) {
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expA = 1;
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expB = 1;
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}
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if ( sigB < sigA ) goto aBigger;
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if ( sigA < sigB ) goto bBigger;
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uiZ = packToF32UI( softfloat_roundingMode == softfloat_round_min, 0, 0 );
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goto uiZ;
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expBBigger:
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if ( expB == 0xFF ) {
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if ( sigB ) goto propagateNaN;
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uiZ = packToF32UI( signZ ^ 1, 0xFF, 0 );
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goto uiZ;
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}
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sigA += expA ? 0x40000000 : sigA;
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sigA = softfloat_shiftRightJam32( sigA, -expDiff );
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sigB |= 0x40000000;
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bBigger:
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signZ ^= 1;
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expZ = expB;
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sigZ = sigB - sigA;
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goto normRoundPack;
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expABigger:
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if ( expA == 0xFF ) {
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if ( sigA ) goto propagateNaN;
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uiZ = uiA;
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goto uiZ;
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}
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sigB += expB ? 0x40000000 : sigB;
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sigB = softfloat_shiftRightJam32( sigB, expDiff );
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sigA |= 0x40000000;
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aBigger:
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expZ = expA;
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sigZ = sigA - sigB;
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normRoundPack:
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return softfloat_normRoundPackToF32( signZ, expZ - 1, sigZ );
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propagateNaN:
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uiZ = softfloat_propagateNaNF32UI( uiA, uiB );
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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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