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/* Compute maximum of two numbers, regarding NaN as missing argument.
Copyright (C) 1997-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <libm-alias-ldouble.h>
#include <sysdep.h>
.text
ENTRY(__fmaxl)
fldt 16(%esp) // y
fxam
fnstsw
fldt 4(%esp) // y : x
andb $0x45, %ah
cmpb $0x01, %ah
je 2f // y == NaN
fxam
fnstsw
andb $0x45, %ah
cmpb $0x01, %ah
je 3f // x == NaN
fucom %st(1)
fnstsw
sahf
jnc 1f
fxch %st(1)
1: fstp %st(1)
ret
2: // st(1) is a NaN; st(0) may or may not be.
fxam
fnstsw
andb $0x45, %ah
cmpb $0x01, %ah
je 4f
// st(1) is a NaN; st(0) is not. Test if st(1) is signaling.
testb $0x40, 23(%esp)
jz 4f
fstp %st(1)
ret
3: // st(0) is a NaN; st(1) is not. Test if st(0) is signaling.
testb $0x40, 11(%esp)
jz 4f
fstp %st(0)
ret
4: // Both arguments are NaNs, or one is a signaling NaN.
faddp
ret
END(__fmaxl)
libm_alias_ldouble (__fmax, fmax)
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