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/* IEEE754 floating point arithmetic
* double precision: common utilities
*/
/*
* 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 "ieee754dp.h"
int ieee754dp_tint(union ieee754dp x)
{
u64 residue;
int round;
int sticky;
int odd;
COMPXDP;
ieee754_clearcx();
EXPLODEXDP;
FLUSHXDP;
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) {
/* Set invalid. We will only use overflow for floating
point overflow */
ieee754_setcx(IEEE754_INVALID_OPERATION);
return ieee754si_indef();
}
/* oh gawd */
if (xe > DP_FBITS) {
xm <<= xe - DP_FBITS;
} else if (xe < DP_FBITS) {
if (xe < -1) {
residue = xm;
round = 0;
sticky = residue != 0;
xm = 0;
} else {
residue = xm << (64 - DP_FBITS + xe);
round = (residue >> 63) != 0;
sticky = (residue << 1) != 0;
xm >>= DP_FBITS - xe;
}
/* Note: At this point upper 32 bits of xm are guaranteed
to be zero */
odd = (xm & 0x1) != 0x0;
switch (ieee754_csr.rm) {
case IEEE754_RN:
if (round && (sticky || odd))
xm++;
break;
case IEEE754_RZ:
break;
case IEEE754_RU: /* toward +Infinity */
if ((round || sticky) && !xs)
xm++;
break;
case IEEE754_RD: /* toward -Infinity */
if ((round || sticky) && xs)
xm++;
break;
}
/* look for valid corner case 0x80000000 */
if ((xm >> 31) != 0 && (xs == 0 || xm != 0x80000000)) {
/* 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;
}
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