1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
80 lines
2 KiB
C
80 lines
2 KiB
C
/* IEEE754 floating point arithmetic
|
|
* double precision: common utilities
|
|
*/
|
|
/*
|
|
* MIPS floating point support
|
|
* Copyright (C) 1994-2000 Algorithmics Ltd.
|
|
* http://www.algor.co.uk
|
|
*
|
|
* ########################################################################
|
|
*
|
|
* 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.,
|
|
* 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
|
|
*
|
|
* ########################################################################
|
|
*/
|
|
|
|
|
|
#include "ieee754dp.h"
|
|
|
|
/* modf function is always exact for a finite number
|
|
*/
|
|
ieee754dp ieee754dp_modf(ieee754dp x, ieee754dp * ip)
|
|
{
|
|
COMPXDP;
|
|
|
|
CLEARCX;
|
|
|
|
EXPLODEXDP;
|
|
|
|
switch (xc) {
|
|
case IEEE754_CLASS_SNAN:
|
|
case IEEE754_CLASS_QNAN:
|
|
case IEEE754_CLASS_INF:
|
|
case IEEE754_CLASS_ZERO:
|
|
*ip = x;
|
|
return x;
|
|
case IEEE754_CLASS_DNORM:
|
|
/* far to small */
|
|
*ip = ieee754dp_zero(xs);
|
|
return x;
|
|
case IEEE754_CLASS_NORM:
|
|
break;
|
|
}
|
|
if (xe < 0) {
|
|
*ip = ieee754dp_zero(xs);
|
|
return x;
|
|
}
|
|
if (xe >= DP_MBITS) {
|
|
*ip = x;
|
|
return ieee754dp_zero(xs);
|
|
}
|
|
/* generate ipart mantissa by clearing bottom bits
|
|
*/
|
|
*ip = builddp(xs, xe + DP_EBIAS,
|
|
((xm >> (DP_MBITS - xe)) << (DP_MBITS - xe)) &
|
|
~DP_HIDDEN_BIT);
|
|
|
|
/* generate fpart mantissa by clearing top bits
|
|
* and normalizing (must be able to normalize)
|
|
*/
|
|
xm = (xm << (64 - (DP_MBITS - xe))) >> (64 - (DP_MBITS - xe));
|
|
if (xm == 0)
|
|
return ieee754dp_zero(xs);
|
|
|
|
while ((xm >> DP_MBITS) == 0) {
|
|
xm <<= 1;
|
|
xe--;
|
|
}
|
|
return builddp(xs, xe + DP_EBIAS, xm & ~DP_HIDDEN_BIT);
|
|
}
|