56a6473339
Previously math-emu was using the IEEE-754 constants internally. These were differing by having the constants for rounding to +/- infinity switched, so a conversion was necessary. This would be entirely avoidable if the MIPS constants were used throughout, so get rid of the bloat. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
110 lines
2.5 KiB
C
110 lines
2.5 KiB
C
/* IEEE754 floating point arithmetic
|
|
* single precision
|
|
*/
|
|
/*
|
|
* MIPS floating point support
|
|
* Copyright (C) 1994-2000 Algorithmics Ltd.
|
|
*
|
|
* This program is free software; you can distribute it and/or modify it
|
|
* under the terms of the GNU General Public License (Version 2) as
|
|
* published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope it will be useful, but WITHOUT
|
|
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
* for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License along
|
|
* with this program; if not, write to the Free Software Foundation, Inc.,
|
|
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
*/
|
|
|
|
#include "ieee754sp.h"
|
|
|
|
int ieee754sp_tint(union ieee754sp x)
|
|
{
|
|
u32 residue;
|
|
int round;
|
|
int sticky;
|
|
int odd;
|
|
|
|
COMPXSP;
|
|
|
|
ieee754_clearcx();
|
|
|
|
EXPLODEXSP;
|
|
FLUSHXSP;
|
|
|
|
switch (xc) {
|
|
case IEEE754_CLASS_SNAN:
|
|
case IEEE754_CLASS_QNAN:
|
|
case IEEE754_CLASS_INF:
|
|
ieee754_setcx(IEEE754_INVALID_OPERATION);
|
|
return ieee754si_indef();
|
|
|
|
case IEEE754_CLASS_ZERO:
|
|
return 0;
|
|
|
|
case IEEE754_CLASS_DNORM:
|
|
case IEEE754_CLASS_NORM:
|
|
break;
|
|
}
|
|
if (xe >= 31) {
|
|
/* look for valid corner case */
|
|
if (xe == 31 && xs && xm == SP_HIDDEN_BIT)
|
|
return -0x80000000;
|
|
/* Set invalid. We will only use overflow for floating
|
|
point overflow */
|
|
ieee754_setcx(IEEE754_INVALID_OPERATION);
|
|
return ieee754si_indef();
|
|
}
|
|
/* oh gawd */
|
|
if (xe > SP_FBITS) {
|
|
xm <<= xe - SP_FBITS;
|
|
} else {
|
|
if (xe < -1) {
|
|
residue = xm;
|
|
round = 0;
|
|
sticky = residue != 0;
|
|
xm = 0;
|
|
} else {
|
|
/* Shifting a u32 32 times does not work,
|
|
* so we do it in two steps. Be aware that xe
|
|
* may be -1 */
|
|
residue = xm << (xe + 1);
|
|
residue <<= 31 - SP_FBITS;
|
|
round = (residue >> 31) != 0;
|
|
sticky = (residue << 1) != 0;
|
|
xm >>= SP_FBITS - xe;
|
|
}
|
|
odd = (xm & 0x1) != 0x0;
|
|
switch (ieee754_csr.rm) {
|
|
case FPU_CSR_RN:
|
|
if (round && (sticky || odd))
|
|
xm++;
|
|
break;
|
|
case FPU_CSR_RZ:
|
|
break;
|
|
case FPU_CSR_RU: /* toward +Infinity */
|
|
if ((round || sticky) && !xs)
|
|
xm++;
|
|
break;
|
|
case FPU_CSR_RD: /* toward -Infinity */
|
|
if ((round || sticky) && xs)
|
|
xm++;
|
|
break;
|
|
}
|
|
if ((xm >> 31) != 0) {
|
|
/* This can happen after rounding */
|
|
ieee754_setcx(IEEE754_INVALID_OPERATION);
|
|
return ieee754si_indef();
|
|
}
|
|
if (round || sticky)
|
|
ieee754_setcx(IEEE754_INEXACT);
|
|
}
|
|
if (xs)
|
|
return -xm;
|
|
else
|
|
return xm;
|
|
}
|