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c5033d7803
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>
90 lines
2 KiB
C
90 lines
2 KiB
C
/* IEEE754 floating point arithmetic
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* double precision: common utilities
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*/
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/*
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* MIPS floating point support
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* Copyright (C) 1994-2000 Algorithmics Ltd.
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* http://www.algor.co.uk
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*
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* ########################################################################
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*
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* This program is free software; you can distribute it and/or modify it
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* under the terms of the GNU General Public License (Version 2) as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
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*
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* ########################################################################
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*/
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#include "ieee754dp.h"
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int ieee754dp_finite(ieee754dp x)
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{
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return DPBEXP(x) != DP_EMAX + 1 + DP_EBIAS;
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}
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ieee754dp ieee754dp_copysign(ieee754dp x, ieee754dp y)
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{
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CLEARCX;
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DPSIGN(x) = DPSIGN(y);
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return x;
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}
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ieee754dp ieee754dp_neg(ieee754dp x)
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{
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COMPXDP;
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EXPLODEXDP;
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CLEARCX;
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FLUSHXDP;
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/*
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* Invert the sign ALWAYS to prevent an endless recursion on
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* pow() in libc.
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*/
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/* quick fix up */
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DPSIGN(x) ^= 1;
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if (xc == IEEE754_CLASS_SNAN) {
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ieee754dp y = ieee754dp_indef();
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SETCX(IEEE754_INVALID_OPERATION);
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DPSIGN(y) = DPSIGN(x);
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return ieee754dp_nanxcpt(y, "neg");
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}
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if (ieee754dp_isnan(x)) /* but not infinity */
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return ieee754dp_nanxcpt(x, "neg", x);
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return x;
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}
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ieee754dp ieee754dp_abs(ieee754dp x)
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{
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COMPXDP;
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EXPLODEXDP;
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CLEARCX;
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FLUSHXDP;
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if (xc == IEEE754_CLASS_SNAN) {
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SETCX(IEEE754_INVALID_OPERATION);
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return ieee754dp_nanxcpt(ieee754dp_indef(), "neg");
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}
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if (ieee754dp_isnan(x)) /* but not infinity */
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return ieee754dp_nanxcpt(x, "abs", x);
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/* quick fix up */
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DPSIGN(x) = 0;
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return x;
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}
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