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Diffstat (limited to 'source/s_roundPackToBF16.c')
| -rw-r--r-- | source/s_roundPackToBF16.c | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/source/s_roundPackToBF16.c b/source/s_roundPackToBF16.c new file mode 100644 index 0000000..57a7ae4 --- /dev/null +++ b/source/s_roundPackToBF16.c @@ -0,0 +1,114 @@ + +/*============================================================================ + +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, 2017 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 "internals.h" +#include "softfloat.h" + +/** sig last significant bit is sig[7], the 7 LSBs will be used for rounding */ +bfloat16_t + softfloat_roundPackToBF16( bool sign, int_fast16_t exp, uint_fast16_t sig ) +{ + uint_fast8_t roundingMode; + bool roundNearEven; + uint_fast8_t roundIncrement, roundBits; + bool isTiny; + uint_fast16_t uiZ; + union ui16_bf16 uZ; + + /*------------------------------------------------------------------------ + *------------------------------------------------------------------------*/ + roundingMode = softfloat_roundingMode; + roundNearEven = (roundingMode == softfloat_round_near_even); + roundIncrement = 0x40; + if ( ! roundNearEven && (roundingMode != softfloat_round_near_maxMag) ) { + roundIncrement = + (roundingMode + == (sign ? softfloat_round_min : softfloat_round_max)) + ? 0x7F + : 0; + } + roundBits = sig & 0x7F; + /*------------------------------------------------------------------------ + *------------------------------------------------------------------------*/ + if ( 0xFD <= (unsigned int) exp ) { + if ( exp < 0 ) { + /*---------------------------------------------------------------- + *----------------------------------------------------------------*/ + isTiny = + (softfloat_detectTininess == softfloat_tininess_beforeRounding) + || (exp < -1) || (sig + roundIncrement < 0x8000); + sig = softfloat_shiftRightJam32( sig, -exp ); + exp = 0; + roundBits = sig & 0x7F; + if ( isTiny && roundBits ) { + softfloat_raiseFlags( softfloat_flag_underflow ); + } + } else if ( (0xFD < exp) || (0x8000 <= sig + roundIncrement) ) { + /*---------------------------------------------------------------- + *----------------------------------------------------------------*/ + softfloat_raiseFlags( + softfloat_flag_overflow | softfloat_flag_inexact ); + uiZ = packToBF16UI( sign, 0xFF, 0 ) - ! roundIncrement; + goto uiZ; + } + } + /*------------------------------------------------------------------------ + *------------------------------------------------------------------------*/ + sig = (sig + roundIncrement)>>7; + if ( roundBits ) { + softfloat_exceptionFlags |= softfloat_flag_inexact; +#ifdef SOFTFLOAT_ROUND_ODD + if ( roundingMode == softfloat_round_odd ) { + sig |= 1; + goto packReturn; + } +#endif + } + sig &= ~(uint_fast16_t) (! (roundBits ^ 0x40) & roundNearEven); + if ( ! sig ) exp = 0; + /*------------------------------------------------------------------------ + *------------------------------------------------------------------------*/ + packReturn: + uiZ = packToBF16UI( sign, exp, sig ); + uiZ: + uZ.ui = uiZ; + return uZ.f; + +} + |