linux/arch/mips/math-emu/sp_simple.c
Atsushi Nemoto c5033d7803 [MIPS] ieee754[sd]p_neg workaround
It looks glibc's pow() assumes an unary '-' operation for any number
(including NaNs) always inverts its sign bit (though IEEE754 does not
specify the sign bit for NaNs).  This patch make the kernel math-emu
emulates real MIPS neg.[ds] instruction.
    
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-02-07 13:30:25 +00:00

90 lines
2 KiB
C

/* IEEE754 floating point arithmetic
* single precision
*/
/*
* 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 "ieee754sp.h"
int ieee754sp_finite(ieee754sp x)
{
return SPBEXP(x) != SP_EMAX + 1 + SP_EBIAS;
}
ieee754sp ieee754sp_copysign(ieee754sp x, ieee754sp y)
{
CLEARCX;
SPSIGN(x) = SPSIGN(y);
return x;
}
ieee754sp ieee754sp_neg(ieee754sp x)
{
COMPXSP;
EXPLODEXSP;
CLEARCX;
FLUSHXSP;
/*
* Invert the sign ALWAYS to prevent an endless recursion on
* pow() in libc.
*/
/* quick fix up */
SPSIGN(x) ^= 1;
if (xc == IEEE754_CLASS_SNAN) {
ieee754sp y = ieee754sp_indef();
SETCX(IEEE754_INVALID_OPERATION);
SPSIGN(y) = SPSIGN(x);
return ieee754sp_nanxcpt(y, "neg");
}
if (ieee754sp_isnan(x)) /* but not infinity */
return ieee754sp_nanxcpt(x, "neg", x);
return x;
}
ieee754sp ieee754sp_abs(ieee754sp x)
{
COMPXSP;
EXPLODEXSP;
CLEARCX;
FLUSHXSP;
if (xc == IEEE754_CLASS_SNAN) {
SETCX(IEEE754_INVALID_OPERATION);
return ieee754sp_nanxcpt(ieee754sp_indef(), "abs");
}
if (ieee754sp_isnan(x)) /* but not infinity */
return ieee754sp_nanxcpt(x, "abs", x);
/* quick fix up */
SPSIGN(x) = 0;
return x;
}