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author | John Hauser <jhauser@eecs.berkeley.edu> | 2014-11-28 19:49:28 -0800 |
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committer | John Hauser <jhauser@eecs.berkeley.edu> | 2014-11-28 19:49:28 -0800 |
commit | 8f59d925353145a65c09301dea6c47da1f1311b1 (patch) | |
tree | c55a81490cc411be6c812a5bfcc8fdc48296def9 /source/s_subMagsF128.c | |
download | berkeley-softfloat-3-8f59d925353145a65c09301dea6c47da1f1311b1.zip berkeley-softfloat-3-8f59d925353145a65c09301dea6c47da1f1311b1.tar.gz berkeley-softfloat-3-8f59d925353145a65c09301dea6c47da1f1311b1.tar.bz2 |
First draft of RC for Release 3, to start review process.
Diffstat (limited to 'source/s_subMagsF128.c')
-rw-r--r-- | source/s_subMagsF128.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/source/s_subMagsF128.c b/source/s_subMagsF128.c new file mode 100644 index 0000000..de702ab --- /dev/null +++ b/source/s_subMagsF128.c @@ -0,0 +1,136 @@ + +/*============================================================================ + +This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic +Package, Release 3, by John R. Hauser. + +Copyright 2011, 2012, 2013, 2014 The Regents of the University of California +(Regents). All Rights Reserved. Redistribution and use in source and binary +forms, with or without modification, are permitted provided that the following +conditions are met: + +Redistributions of source code must retain the above copyright notice, +this list of conditions, and the following two paragraphs of disclaimer. +Redistributions in binary form must reproduce the above copyright notice, +this list of conditions, and the following two paragraphs of disclaimer in the +documentation and/or other materials provided with the distribution. Neither +the name of the Regents nor the names of its contributors may be used to +endorse or promote products derived from this software without specific prior +written permission. + +IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, +SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING +OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF REGENTS HAS +BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED +TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR +PURPOSE. THE SOFTWARE AND ACCOMPANYING DOCUMENTATION, IF ANY, PROVIDED +HEREUNDER IS PROVIDED "AS IS". REGENTS HAS NO OBLIGATION TO PROVIDE +MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. + +=============================================================================*/ + +#include <stdbool.h> +#include <stdint.h> +#include "platform.h" +#include "internals.h" +#include "specialize.h" +#include "softfloat.h" + +float128_t + softfloat_subMagsF128( + uint_fast64_t uiA64, + uint_fast64_t uiA0, + uint_fast64_t uiB64, + uint_fast64_t uiB0, + bool signZ + ) +{ + int_fast32_t expA; + struct uint128 sigA; + int_fast32_t expB; + struct uint128 sigB, sigZ; + int_fast32_t expDiff, expZ; + struct uint128 uiZ; + union ui128_f128 uZ; + + expA = expF128UI64( uiA64 ); + sigA.v64 = fracF128UI64( uiA64 ); + sigA.v0 = uiA0; + expB = expF128UI64( uiB64 ); + sigB.v64 = fracF128UI64( uiB64 ); + sigB.v0 = uiB0; + sigA = softfloat_shortShiftLeft128( sigA.v64, sigA.v0, 4 ); + sigB = softfloat_shortShiftLeft128( sigB.v64, sigB.v0, 4 ); + expDiff = expA - expB; + if ( 0 < expDiff ) goto expABigger; + if ( expDiff < 0 ) goto expBBigger; + if ( expA == 0x7FFF ) { + if ( sigA.v64 | sigA.v0 | sigB.v64 | sigB.v0 ) goto propagateNaN; + softfloat_raiseFlags( softfloat_flag_invalid ); + uiZ.v64 = defaultNaNF128UI64; + uiZ.v0 = defaultNaNF128UI0; + goto uiZ; + } + expZ = expA; + if ( ! expZ ) expZ = 1; + if ( sigB.v64 < sigA.v64 ) goto aBigger; + if ( sigA.v64 < sigB.v64 ) goto bBigger; + if ( sigB.v0 < sigA.v0 ) goto aBigger; + if ( sigA.v0 < sigB.v0 ) goto bBigger; + uiZ.v64 = + packToF128UI64( + (softfloat_roundingMode == softfloat_round_min), 0, 0 ); + uiZ.v0 = 0; + goto uiZ; + expBBigger: + if ( expB == 0x7FFF ) { + if ( sigB.v64 | sigB.v0 ) goto propagateNaN; + uiZ.v64 = packToF128UI64( signZ ^ 1, 0x7FFF, 0 ); + uiZ.v0 = 0; + goto uiZ; + } + if ( expA ) { + sigA.v64 |= UINT64_C( 0x0010000000000000 ); + } else { + ++expDiff; + if ( ! expDiff ) goto newlyAlignedBBigger; + } + sigA = softfloat_shiftRightJam128( sigA.v64, sigA.v0, -expDiff ); + newlyAlignedBBigger: + expZ = expB; + sigB.v64 |= UINT64_C( 0x0010000000000000 ); + bBigger: + signZ ^= 1; + sigZ = softfloat_sub128( sigB.v64, sigB.v0, sigA.v64, sigA.v0 ); + goto normRoundPack; + expABigger: + if ( expA == 0x7FFF ) { + if ( sigA.v64 | sigA.v0 ) goto propagateNaN; + uiZ.v64 = uiA64; + uiZ.v0 = uiA0; + goto uiZ; + } + if ( expB ) { + sigB.v64 |= UINT64_C( 0x0010000000000000 ); + } else { + --expDiff; + if ( ! expDiff ) goto newlyAlignedABigger; + } + sigB = softfloat_shiftRightJam128( sigB.v64, sigB.v0, expDiff ); + newlyAlignedABigger: + expZ = expA; + sigA.v64 |= UINT64_C( 0x0010000000000000 ); + aBigger: + sigZ = softfloat_sub128( sigA.v64, sigA.v0, sigB.v64, sigB.v0 ); + normRoundPack: + return softfloat_normRoundPackToF128( signZ, expZ - 5, sigZ.v64, sigZ.v0 ); + propagateNaN: + uiZ = softfloat_propagateNaNF128UI( uiA64, uiA0, uiB64, uiB0 ); + uiZ: + uZ.ui = uiZ; + return uZ.f; + +} + |