106 lines
4.2 KiB
C
106 lines
4.2 KiB
C
|
|
||
|
|
/*============================================================================
|
||
|
|
|
||
|
|
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 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 "specialize.h"
|
||
|
|
#include "softfloat.h"
|
||
|
|
|
||
|
|
#include <inttypes.h>
|
||
|
|
#include <stdio.h>
|
||
|
|
|
||
|
|
bfloat16_t f32_to_bf16( float32_t a )
|
||
|
|
{
|
||
|
|
union ui32_f32 uA;
|
||
|
|
uint_fast32_t uiA;
|
||
|
|
bool sign;
|
||
|
|
int_fast16_t exp;
|
||
|
|
uint_fast32_t frac;
|
||
|
|
struct commonNaN commonNaN;
|
||
|
|
uint_fast16_t uiZ, frac16;
|
||
|
|
union ui16_bf16 uZ;
|
||
|
|
|
||
|
|
/*------------------------------------------------------------------------
|
||
|
|
*------------------------------------------------------------------------*/
|
||
|
|
uA.f = a;
|
||
|
|
uiA = uA.ui;
|
||
|
|
sign = signF32UI( uiA );
|
||
|
|
exp = expF32UI( uiA );
|
||
|
|
frac = fracF32UI( uiA );
|
||
|
|
/*------------------------------------------------------------------------
|
||
|
|
*------------------------------------------------------------------------*/
|
||
|
|
// infinity or NaN cases
|
||
|
|
if ( exp == 0xFF ) {
|
||
|
|
if ( frac ) {
|
||
|
|
// NaN case
|
||
|
|
softfloat_f32UIToCommonNaN( uiA, &commonNaN );
|
||
|
|
uiZ = softfloat_commonNaNToBF16UI( &commonNaN );
|
||
|
|
} else {
|
||
|
|
// infinity case
|
||
|
|
uiZ = packToBF16UI( sign, 0xFF, 0 );
|
||
|
|
}
|
||
|
|
goto uiZ;
|
||
|
|
}
|
||
|
|
/*------------------------------------------------------------------------
|
||
|
|
*------------------------------------------------------------------------*/
|
||
|
|
// frac is a 24-bit mantissa, right shifted by 9
|
||
|
|
// In the normal case, (24-9) = 15 are set
|
||
|
|
frac16 = frac>>9 | ((frac & 0x1FF) != 0);
|
||
|
|
if ( ! (exp | frac16) ) {
|
||
|
|
uiZ = packToBF16UI( sign, 0, 0 );
|
||
|
|
goto uiZ;
|
||
|
|
}
|
||
|
|
/*------------------------------------------------------------------------
|
||
|
|
*------------------------------------------------------------------------*/
|
||
|
|
// softfloat_roundPackToBF16 exponent argument (2nd argument)
|
||
|
|
// must correspond to the exponent of fracIn[13] bits
|
||
|
|
// (fracIn is the 3rd and last argument)
|
||
|
|
uint_fast32_t mask = exp ? 0x4000 : 0x0; // implicit one mask added if input is a normal number
|
||
|
|
// exponent for the lowest normal and largest subnormal should be equal
|
||
|
|
// but is not in IEEE encoding so mantissa must be partially normalized
|
||
|
|
// (by one bit) for subnormal numbers. Such that (exp - 1) corresponds
|
||
|
|
// to the exponent of frac16[13]
|
||
|
|
frac16 = frac16 << (exp ? 0 : 1);
|
||
|
|
return softfloat_roundPackToBF16( sign, exp - 1, frac16 | mask );
|
||
|
|
uiZ:
|
||
|
|
uZ.ui = uiZ;
|
||
|
|
return uZ.f;
|
||
|
|
|
||
|
|
}
|
||
|
|
|