192 lines
7.7 KiB
C
192 lines
7.7 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, 2016, 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 "internals.h"
|
|
#include "primitives.h"
|
|
#include "specialize.h"
|
|
#include "softfloat.h"
|
|
|
|
float16_t softfloat_subMagsF16(uint16_t uiA, uint16_t uiB, struct softfloat_status_t *status)
|
|
{
|
|
int8_t expA;
|
|
uint16_t sigA;
|
|
int8_t expB;
|
|
uint16_t sigB;
|
|
int8_t expDiff;
|
|
uint16_t uiZ;
|
|
int16_t sigDiff;
|
|
bool signZ;
|
|
int8_t shiftDist, expZ;
|
|
uint16_t sigZ, sigX, sigY;
|
|
uint32_t sig32Z;
|
|
int8_t roundingMode;
|
|
|
|
/*------------------------------------------------------------------------
|
|
*------------------------------------------------------------------------*/
|
|
expA = expF16UI(uiA);
|
|
sigA = fracF16UI(uiA);
|
|
expB = expF16UI(uiB);
|
|
sigB = fracF16UI(uiB);
|
|
/*------------------------------------------------------------------------
|
|
*------------------------------------------------------------------------*/
|
|
if (softfloat_denormalsAreZeros(status)) {
|
|
if (!expA) sigA = 0;
|
|
if (!expB) sigB = 0;
|
|
}
|
|
/*------------------------------------------------------------------------
|
|
*------------------------------------------------------------------------*/
|
|
expDiff = expA - expB;
|
|
if (! expDiff) {
|
|
/*--------------------------------------------------------------------
|
|
*--------------------------------------------------------------------*/
|
|
if (expA == 0x1F) {
|
|
if (sigA | sigB) goto propagateNaN;
|
|
softfloat_raiseFlags(status, softfloat_flag_invalid);
|
|
return defaultNaNF16UI;
|
|
}
|
|
if (!expA && (sigA | sigB)) softfloat_raiseFlags(status, softfloat_flag_denormal);
|
|
sigDiff = sigA - sigB;
|
|
if (! sigDiff) {
|
|
return packToF16UI((softfloat_getRoundingMode(status) == softfloat_round_min), 0, 0);
|
|
}
|
|
if (expA) --expA;
|
|
signZ = signF16UI(uiA);
|
|
if (sigDiff < 0) {
|
|
signZ = ! signZ;
|
|
sigDiff = -sigDiff;
|
|
}
|
|
shiftDist = softfloat_countLeadingZeros16(sigDiff) - 5;
|
|
expZ = expA - shiftDist;
|
|
if (expZ < 0) {
|
|
shiftDist = expA;
|
|
expZ = 0;
|
|
}
|
|
sigZ = sigDiff<<shiftDist;
|
|
if (!expZ && sigDiff) {
|
|
if (softfloat_flushUnderflowToZero(status)) {
|
|
softfloat_raiseFlags(status, softfloat_flag_underflow | softfloat_flag_inexact);
|
|
return packToF16UI(signZ, 0, 0);
|
|
}
|
|
if (! softfloat_isMaskedException(status, softfloat_flag_underflow)) {
|
|
softfloat_raiseFlags(status, softfloat_flag_underflow);
|
|
}
|
|
}
|
|
goto pack;
|
|
} else {
|
|
/*--------------------------------------------------------------------
|
|
*--------------------------------------------------------------------*/
|
|
signZ = signF16UI(uiA);
|
|
if (expDiff < 0) {
|
|
/*----------------------------------------------------------------
|
|
*----------------------------------------------------------------*/
|
|
signZ = ! signZ;
|
|
if (expB == 0x1F) {
|
|
if (sigB) goto propagateNaN;
|
|
if (sigA && !expA) softfloat_raiseFlags(status, softfloat_flag_denormal);
|
|
return packToF16UI(signZ, 0x1F, 0);
|
|
}
|
|
|
|
if ((sigA && !expA) || (sigB && !expB))
|
|
softfloat_raiseFlags(status, softfloat_flag_denormal);
|
|
|
|
if (expDiff <= -13) {
|
|
uiZ = packToF16UI(signZ, expB, sigB);
|
|
if (expA | sigA) goto subEpsilon;
|
|
return uiZ;
|
|
}
|
|
expZ = expA + 19;
|
|
sigX = sigB | 0x0400;
|
|
sigY = sigA + (expA ? 0x0400 : sigA);
|
|
expDiff = -expDiff;
|
|
} else {
|
|
/*----------------------------------------------------------------
|
|
*----------------------------------------------------------------*/
|
|
uiZ = uiA;
|
|
if (expA == 0x1F) {
|
|
if (sigA) goto propagateNaN;
|
|
if (sigB && !expB) softfloat_raiseFlags(status, softfloat_flag_denormal);
|
|
return uiZ;
|
|
}
|
|
|
|
if ((sigA && !expA) || (sigB && !expB))
|
|
softfloat_raiseFlags(status, softfloat_flag_denormal);
|
|
|
|
if (13 <= expDiff) {
|
|
if (expB | sigB) goto subEpsilon;
|
|
return uiZ;
|
|
}
|
|
expZ = expB + 19;
|
|
sigX = sigA | 0x0400;
|
|
sigY = sigB + (expB ? 0x0400 : sigB);
|
|
}
|
|
sig32Z = ((uint32_t) sigX<<expDiff) - sigY;
|
|
shiftDist = softfloat_countLeadingZeros32(sig32Z) - 1;
|
|
sig32Z <<= shiftDist;
|
|
expZ -= shiftDist;
|
|
sigZ = sig32Z>>16;
|
|
if (sig32Z & 0xFFFF) {
|
|
sigZ |= 1;
|
|
} else {
|
|
if (! (sigZ & 0xF) && ((unsigned int) expZ < 0x1E)) {
|
|
sigZ >>= 4;
|
|
goto pack;
|
|
}
|
|
}
|
|
return softfloat_roundPackToF16(signZ, expZ, sigZ, status);
|
|
}
|
|
/*------------------------------------------------------------------------
|
|
*------------------------------------------------------------------------*/
|
|
propagateNaN:
|
|
return softfloat_propagateNaNF16UI(uiA, uiB, status);
|
|
/*------------------------------------------------------------------------
|
|
*------------------------------------------------------------------------*/
|
|
subEpsilon:
|
|
roundingMode = softfloat_getRoundingMode(status);
|
|
if (roundingMode != softfloat_round_near_even) {
|
|
if ((roundingMode == softfloat_round_minMag)
|
|
|| (roundingMode == (signF16UI(uiZ) ? softfloat_round_max : softfloat_round_min))) {
|
|
--uiZ;
|
|
}
|
|
}
|
|
softfloat_raiseFlags(status, softfloat_flag_inexact);
|
|
return uiZ;
|
|
/*------------------------------------------------------------------------
|
|
*------------------------------------------------------------------------*/
|
|
pack:
|
|
return packToF16UI(signZ, expZ, sigZ);
|
|
}
|