diff options
Diffstat (limited to 'source/s_subMagsF32.c')
| -rw-r--r-- | source/s_subMagsF32.c | 128 |
1 files changed, 78 insertions, 50 deletions
diff --git a/source/s_subMagsF32.c b/source/s_subMagsF32.c index ba5ac9a..012d4da 100644 --- a/source/s_subMagsF32.c +++ b/source/s_subMagsF32.c @@ -2,10 +2,10 @@ /*============================================================================ This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic -Package, Release 3a, by John R. Hauser. +Package, Release 3b, by John R. Hauser. -Copyright 2011, 2012, 2013, 2014 The Regents of the University of California. -All rights reserved. +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: @@ -41,8 +41,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. #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; @@ -50,61 +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; + 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 ) + ); } - 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_shiftRightJam32( sigA, -expDiff ); - sigB |= 0x40000000; - bBigger: - signZ ^= 1; - expZ = expB; - sigZ = sigB - sigA; - goto normRoundPack; - expABigger: - if ( expA == 0xFF ) { - if ( sigA ) goto propagateNaN; - uiZ = uiA; - goto uiZ; - } - sigB += expB ? 0x40000000 : sigB; - sigB = softfloat_shiftRightJam32( 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: |