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/* ix87 specific implementation of exp(x)-1.
Copyright (C) 1996, 1997 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
Based on code by John C. Bowman <bowman@ipp-garching.mpg.de>.
Corrections by H.J. Lu (hjl@gnu.ai.mit.edu), 1997.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
/* Using: e^x - 1 = 2^(x * log2(e)) - 1 */
#include <machine/asm.h>
#ifdef __ELF__
.section .rodata
#else
.text
#endif
.align ALIGNARG(4)
ASM_TYPE_DIRECTIVE(minus1,@object)
minus1: .double -1.0
ASM_SIZE_DIRECTIVE(minus1)
ASM_TYPE_DIRECTIVE(one,@object)
one: .double 1.0
ASM_SIZE_DIRECTIVE(one)
ASM_TYPE_DIRECTIVE(l2e,@object)
l2e: .tfloat 1.442695040888963407359924681002
ASM_SIZE_DIRECTIVE(l2e)
#ifdef PIC
#define MO(op) op##@GOTOFF(%edx)
#else
#define MO(op) op
#endif
.text
ENTRY(__expm1)
fldl 4(%esp) // x
fxam // Is NaN or +-Inf?
fstsw %ax
movb $0x45, %ch
andb %ah, %ch
cmpb $0x40, %ch
je 3f // If +-0, jump.
#ifdef PIC
call 1f
1: popl %edx
addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %edx
#endif
cmpb $0x05, %ch
je 2f // If +-Inf, jump.
fldt MO(l2e) // log2(e) : x
fmulp // log2(e)*x
fld %st // log2(e)*x : log2(e)*x
frndint // int(log2(e)*x) : log2(e)*x
fsubr %st, %st(1) // int(log2(e)*x) : fract(log2(e)*x)
fxch // fract(log2(e)*x) : int(log2(e)*x)
f2xm1 // 2^fract(log2(e)*x)-1 : int(log2(e)*x)
fscale // 2^(log2(e)*x)-2^int(log2(e)*x) : int(log2(e)*x)
fxch // int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
fldl MO(one) // 1 : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
fscale // 2^int(log2(e)*x) : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
fsubrl MO(one) // 1-2^int(log2(e)*x) : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
fstp %st(1) // 1-2^int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
fsubrp %st, %st(1) // 2^(log2(e)*x)
ret
2: testl $0x200, %eax // Test sign.
jz 3f // If positive, jump.
fstp %st
fldl MO(minus1) // Set result to -1.0.
3: ret
END(__expm1)
weak_alias (__expm1, expm1)
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