glibc/sysdeps/i386/fpu/s_expm1.S
Siddhesh Poyarekar 30891f35fa Remove "Contributed by" lines
We stopped adding "Contributed by" or similar lines in sources in 2012
in favour of git logs and keeping the Contributors section of the
glibc manual up to date.  Removing these lines makes the license
header a bit more consistent across files and also removes the
possibility of error in attribution when license blocks or files are
copied across since the contributed-by lines don't actually reflect
reality in those cases.

Move all "Contributed by" and similar lines (Written by, Test by,
etc.) into a new file CONTRIBUTED-BY to retain record of these
contributions.  These contributors are also mentioned in
manual/contrib.texi, so we just maintain this additional record as a
courtesy to the earlier developers.

The following scripts were used to filter a list of files to edit in
place and to clean up the CONTRIBUTED-BY file respectively.  These
were not added to the glibc sources because they're not expected to be
of any use in future given that this is a one time task:

https://gist.github.com/siddhesh/b5ecac94eabfd72ed2916d6d8157e7dc
https://gist.github.com/siddhesh/15ea1f5e435ace9774f485030695ee02

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2021-09-03 22:06:44 +05:30

112 lines
3.0 KiB
ArmAsm

/* ix87 specific implementation of exp(x)-1.
Copyright (C) 1996-2021 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/>. */
/* Using: e^x - 1 = 2^(x * log2(e)) - 1 */
#include <sysdep.h>
#include <machine/asm.h>
#include <i386-math-asm.h>
#include <libm-alias-double.h>
.section .rodata
.align ALIGNARG(4)
.type minus1,@object
minus1: .double -1.0
ASM_SIZE_DIRECTIVE(minus1)
.type one,@object
one: .double 1.0
ASM_SIZE_DIRECTIVE(one)
.type l2e,@object
l2e: .tfloat 1.442695040888963407359924681002
ASM_SIZE_DIRECTIVE(l2e)
DEFINE_DBL_MIN
#ifdef PIC
#define MO(op) op##@GOTOFF(%edx)
#else
#define MO(op) op
#endif
.text
ENTRY(__expm1)
movzwl 4+6(%esp), %eax
xorb $0x80, %ah // invert sign bit (now 1 is "positive")
cmpl $0xc086, %eax // is num >= 704?
jae HIDDEN_JUMPTARGET (__exp)
fldl 4(%esp) // x
fxam // Is NaN, +-Inf or +-0?
xorb $0x80, %ah
cmpl $0xc043, %eax // is num <= -38.0?
fstsw %ax
movb $0x45, %ch
jb 4f
// Below -38.0 (may be -NaN or -Inf).
andb %ah, %ch
#ifdef PIC
LOAD_PIC_REG (dx)
#endif
cmpb $0x01, %ch
je 5f // If -NaN, jump.
jmp 2f // -large, possibly -Inf.
4: // In range -38.0 to 704.0 (may be +-0 but not NaN or +-Inf).
andb %ah, %ch
cmpb $0x40, %ch
je 3f // If +-0, jump.
#ifdef PIC
LOAD_PIC_REG (dx)
#endif
5: fldt MO(l2e) // log2(e) : x
fmulp // log2(e)*x
fld %st // log2(e)*x : log2(e)*x
// Set round-to-nearest temporarily.
subl $8, %esp
cfi_adjust_cfa_offset (8)
fstcw 4(%esp)
movl $0xf3ff, %ecx
andl 4(%esp), %ecx
movl %ecx, (%esp)
fldcw (%esp)
frndint // int(log2(e)*x) : log2(e)*x
fldcw 4(%esp)
addl $8, %esp
cfi_adjust_cfa_offset (-8)
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)
DBL_CHECK_FORCE_UFLOW
ret
2: fstp %st
fldl MO(minus1) // Set result to -1.0.
3: ret
END(__expm1)
libm_alias_double (__expm1, expm1)