diff options
Diffstat (limited to 'softfloat/s_subMagsF32.c')
| -rw-r--r--[-rwxr-xr-x] | softfloat/s_subMagsF32.c | 158 |
1 files changed, 109 insertions, 49 deletions
diff --git a/softfloat/s_subMagsF32.c b/softfloat/s_subMagsF32.c index da3a706..8b3aee0 100755..100644 --- a/softfloat/s_subMagsF32.c +++ b/softfloat/s_subMagsF32.c @@ -1,16 +1,47 @@ -// See LICENSE.SoftFloat for license details. +/*============================================================================ + +This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic +Package, Release 3e, by John R. Hauser. + +Copyright 2011, 2012, 2013, 2014, 2015, 2016 The Regents of the University of +California. All rights reserved. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are met: + + 1. Redistributions of source code must retain the above copyright notice, + this list of conditions, and the following disclaimer. + + 2. Redistributions in binary form must reproduce the above copyright notice, + this list of conditions, and the following disclaimer in the documentation + and/or other materials provided with the distribution. + + 3. Neither the name of the University nor the names of its contributors may + be used to endorse or promote products derived from this software without + specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY +EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED +WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE +DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY +DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES +(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; +LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND +ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS +SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +=============================================================================*/ #include <stdbool.h> #include <stdint.h> #include "platform.h" -#include "primitives.h" #include "internals.h" #include "specialize.h" #include "softfloat.h" -float32_t - softfloat_subMagsF32( uint_fast32_t uiA, uint_fast32_t uiB, bool signZ ) +float32_t softfloat_subMagsF32( uint_fast32_t uiA, uint_fast32_t uiB ) { int_fast16_t expA; uint_fast32_t sigA; @@ -18,61 +49,90 @@ float32_t uint_fast32_t sigB; int_fast16_t expDiff; uint_fast32_t uiZ; + int_fast32_t sigDiff; + bool signZ; + int_fast8_t shiftDist; int_fast16_t expZ; - uint_fast32_t sigZ; + uint_fast32_t sigX, sigY; union ui32_f32 uZ; + /*------------------------------------------------------------------------ + *------------------------------------------------------------------------*/ expA = expF32UI( uiA ); sigA = fracF32UI( uiA ); expB = expF32UI( uiB ); sigB = fracF32UI( uiB ); + /*------------------------------------------------------------------------ + *------------------------------------------------------------------------*/ expDiff = expA - expB; - sigA <<= 7; - sigB <<= 7; - if ( 0 < expDiff ) goto expABigger; - if ( expDiff < 0 ) goto expBBigger; - if ( expA == 0xFF ) { - if ( sigA | sigB ) goto propagateNaN; - softfloat_raiseFlags( softfloat_flag_invalid ); - uiZ = defaultNaNF32UI; - goto uiZ; - } - if ( ! expA ) { - expA = 1; - expB = 1; - } - if ( sigB < sigA ) goto aBigger; - if ( sigA < sigB ) goto bBigger; - uiZ = packToF32UI( softfloat_roundingMode == softfloat_round_min, 0, 0 ); - goto uiZ; - expBBigger: - if ( expB == 0xFF ) { - if ( sigB ) goto propagateNaN; - uiZ = packToF32UI( signZ ^ 1, 0xFF, 0 ); - goto uiZ; - } - sigA += expA ? 0x40000000 : sigA; - sigA = softfloat_shift32RightJam( sigA, - expDiff ); - sigB |= 0x40000000; - bBigger: - signZ ^= 1; - expZ = expB; - sigZ = sigB - sigA; - goto normRoundPack; - expABigger: - if ( expA == 0xFF ) { - if ( sigA ) goto propagateNaN; - uiZ = uiA; + if ( ! expDiff ) { + /*-------------------------------------------------------------------- + *--------------------------------------------------------------------*/ + if ( expA == 0xFF ) { + if ( sigA | sigB ) goto propagateNaN; + softfloat_raiseFlags( softfloat_flag_invalid ); + uiZ = defaultNaNF32UI; + goto uiZ; + } + sigDiff = sigA - sigB; + if ( ! sigDiff ) { + uiZ = + packToF32UI( + (softfloat_roundingMode == softfloat_round_min), 0, 0 ); + goto uiZ; + } + if ( expA ) --expA; + signZ = signF32UI( uiA ); + if ( sigDiff < 0 ) { + signZ = ! signZ; + sigDiff = -sigDiff; + } + shiftDist = softfloat_countLeadingZeros32( sigDiff ) - 8; + expZ = expA - shiftDist; + if ( expZ < 0 ) { + shiftDist = expA; + expZ = 0; + } + uiZ = packToF32UI( signZ, expZ, sigDiff<<shiftDist ); goto uiZ; + } else { + /*-------------------------------------------------------------------- + *--------------------------------------------------------------------*/ + signZ = signF32UI( uiA ); + sigA <<= 7; + sigB <<= 7; + if ( expDiff < 0 ) { + /*---------------------------------------------------------------- + *----------------------------------------------------------------*/ + signZ = ! signZ; + if ( expB == 0xFF ) { + if ( sigB ) goto propagateNaN; + uiZ = packToF32UI( signZ, 0xFF, 0 ); + goto uiZ; + } + expZ = expB - 1; + sigX = sigB | 0x40000000; + sigY = sigA + (expA ? 0x40000000 : sigA); + expDiff = -expDiff; + } else { + /*---------------------------------------------------------------- + *----------------------------------------------------------------*/ + if ( expA == 0xFF ) { + if ( sigA ) goto propagateNaN; + uiZ = uiA; + goto uiZ; + } + expZ = expA - 1; + sigX = sigA | 0x40000000; + sigY = sigB + (expB ? 0x40000000 : sigB); + } + return + softfloat_normRoundPackToF32( + signZ, expZ, sigX - softfloat_shiftRightJam32( sigY, expDiff ) + ); } - sigB += expB ? 0x40000000 : sigB; - sigB = softfloat_shift32RightJam( sigB, expDiff ); - sigA |= 0x40000000; - aBigger: - expZ = expA; - sigZ = sigA - sigB; - normRoundPack: - return softfloat_normRoundPackToF32( signZ, expZ - 1, sigZ ); + /*------------------------------------------------------------------------ + *------------------------------------------------------------------------*/ propagateNaN: uiZ = softfloat_propagateNaNF32UI( uiA, uiB ); uiZ: |