Virtualization
/
berkeley-softfloat-3
mirror of https://github.com/ucb-bar/berkeley-softfloat-3.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

Adding more bf16 support function + skeleton for f32_to_bf16

This commit is contained in:
Nicolas Brunie 2023-08-12 06:52:03 +02:00
parent 3d0376df7b
commit ac8688db85
5 changed files with 229 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
source/RISCV/specialize.h
View File

@ -117,6 +117,17 @@ struct commonNaN { char _unused; };
uint_fast16_t
softfloat_propagateNaNF16UI( uint_fast16_t uiA, uint_fast16_t uiB );
/*----------------------------------------------------------------------------
| The bit pattern for a default generated 16-bit BF16 floating-point NaN.
*----------------------------------------------------------------------------*/
#define defaultNaNF16UI 0x7FC0
/*----------------------------------------------------------------------------
| Converts the common NaN pointed to by 'aPtr' into a 16-bit floating-point
| NaN, and returns the bit pattern of this value as an unsigned integer.
*----------------------------------------------------------------------------*/
#define softfloat_commonNaNToBF16UI( aPtr ) ((uint_fast16_t) defaultNaNBF16UI)
/*----------------------------------------------------------------------------
| The bit pattern for a default generated 32-bit floating-point NaN.
*----------------------------------------------------------------------------*/

91
source/f32_to_bf16.c Normal file
View File

@ -0,0 +1,91 @@
/*============================================================================
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"
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;
}
/*------------------------------------------------------------------------
*------------------------------------------------------------------------*/
frac16 = frac>>16 | ((frac & 0xFFFF) != 0);
if ( ! (exp | frac16) ) {
uiZ = packToBF16UI( sign, 0, 0 );
goto uiZ;
}
/*------------------------------------------------------------------------
*------------------------------------------------------------------------*/
return softfloat_roundPackToBF16( sign, exp, frac16 | 0x4000 );
uiZ:
uZ.ui = uiZ;
return uZ.f;
}

3
source/f32_to_f16.c
View File

@ -72,6 +72,9 @@ float16_t f32_to_f16( float32_t a )
}
/*------------------------------------------------------------------------
*------------------------------------------------------------------------*/
// frac is a 24-bit significand, the bottom 9 bits LSB are extracted and OR-red
// into a sticky flag, the top 15 MSBs are extracted, the LSB of this top slice
// is OR-red with the sticky
frac16 = frac>>9 | ((frac & 0x1FF) != 0);
if ( ! (exp | frac16) ) {
uiZ = packToF16UI( sign, 0, 0 );

11
source/include/internals.h
View File

@ -100,6 +100,17 @@ float16_t
softfloat_mulAddF16(
uint_fast16_t, uint_fast16_t, uint_fast16_t, uint_fast8_t );
/*----------------------------------------------------------------------------
*----------------------------------------------------------------------------*/
#define signBF16UI( a ) ((bool) ((uint16_t) (a)>>15))
#define expBF16UI( a ) ((int_fast8_t) ((a)>>7) & 0xFF)
#define fracBF16UI( a ) ((a) & 0x07F)
#define packToBF16UI( sign, exp, sig ) (((uint16_t) (sign)<<15) + ((uint16_t) (exp)<<7) + (sig))
#define isNaNBF16UI( a ) (((~(a) & 0x7FC0) == 0) && ((a) & 0x07F))
bfloat16_t softfloat_roundPackToBF16( bool, int_fast16_t, uint_fast16_t );
/*----------------------------------------------------------------------------
*----------------------------------------------------------------------------*/
#define signF32UI( a ) ((bool) ((uint32_t) (a)>>31))

113
source/s_roundPackToBF16.c Normal file
View File

@ -0,0 +1,113 @@
/*============================================================================
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"
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 = 0x8;
if ( ! roundNearEven && (roundingMode != softfloat_round_near_maxMag) ) {
roundIncrement =
(roundingMode
== (sign ? softfloat_round_min : softfloat_round_max))
? 0xF
: 0;
}
roundBits = sig & 0xF;
/*------------------------------------------------------------------------
*------------------------------------------------------------------------*/
if ( 0x1D <= (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 & 0xF;
if ( isTiny && roundBits ) {
softfloat_raiseFlags( softfloat_flag_underflow );
}
} else if ( (0x1D < exp) || (0x8000 <= sig + roundIncrement) ) {
/*----------------------------------------------------------------
*----------------------------------------------------------------*/
softfloat_raiseFlags(
softfloat_flag_overflow | softfloat_flag_inexact );
uiZ = packToF16UI( sign, 0x1F, 0 ) - ! roundIncrement;
goto uiZ;
}
}
/*------------------------------------------------------------------------
*------------------------------------------------------------------------*/
sig = (sig + roundIncrement)>>4;
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 ^ 8) & roundNearEven);
if ( ! sig ) exp = 0;
/*------------------------------------------------------------------------
*------------------------------------------------------------------------*/
packReturn:
uiZ = packToF16UI( sign, exp, sig );
uiZ:
uZ.ui = uiZ;
return uZ.f;
}