exp10.s revision 25c28e83beb90e7c80452a7c818c5e6f73a07dc8
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
*/
/*
* Copyright 2005 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
.file "exp10.s"
#include "libm.h"
LIBM_ANSI_PRAGMA_WEAK(exp10,function)
#include "libm_synonyms.h"
ENTRY(exp10)
movl 8(%esp),%ecx / ecx <-- hi_32(x)
andl $0x7fffffff,%ecx / ecx <-- hi_32(|x|)
cmpl $0x3fd34413,%ecx / Is |x| < log10(2)?
jb .shortcut / If so, take a shortcut.
je .check_tail / maybe |x| only slightly < log10(2)
cmpl $0x7ff00000,%ecx / hi_32(|x|) >= hi_32(INF)?
jae .not_finite / if so, x is not finite
.finite_non_special: / Here, log10(2) < |x| < INF
fldl 4(%esp) / push x (=arg)
subl $8,%esp / save RP and set round-to-64-bits
fstcw (%esp)
movw (%esp),%ax
movw %ax,4(%esp)
orw $0x0300,%ax
movw %ax,(%esp)
fldcw (%esp)
fldl2t / push log2(10) }NOT for xtndd_dbl
fmulp %st,%st(1) / z = x*log2(10) }NOT for xtndd_dbl
fld %st(0) / duplicate stack top
frndint / [z],z
fucom / z integral?
fstsw %ax
sahf
je .z_integral / branch if z integral
fxch / z, [z]
fsub %st(1),%st / z-[z], [z]
f2xm1 / 2**(z-[z])-1, [z]
fld1 / 1,2**(z-[z])-1, [z]
faddp %st,%st(1) / 2**(z-[z]), [z]
fscale / 2**z = 10**(arg), [z]
fstp %st(1)
fstcw (%esp) / restore old RP
movw (%esp),%dx
andw $0xfcff,%dx
movw 4(%esp),%cx
andw $0x0300,%cx
orw %dx,%cx
movw %cx,(%esp)
fldcw (%esp)
add $8,%esp
ret
.z_integral: / here, z is integral
fstp %st(0) / ,z
fld1 / 1 = 2**0, z
fscale / 2**(0 + z) = 2**z = 10**(arg), z
fstp %st(1) / 10**(arg)
fstcw (%esp) / restore old RP
movw (%esp),%dx
andw $0xfcff,%dx
movw 4(%esp),%cx
andw $0x0300,%cx
orw %dx,%cx
movw %cx,(%esp)
fldcw (%esp)
add $8,%esp
ret
.check_tail:
movl 4(%esp),%edx / edx <-- lo_32(x)
cmpl $0x509f79fe,%edx / Is |x| slightly > log10(2)?
ja .finite_non_special / branch if |x| slightly > log10(2)
.shortcut:
/ Here, |x| < log10(2), so |z| = |x*log2(10)| < 1
/ whence z is in f2xm1's domain.
fldl 4(%esp) / push x (=arg)
fldl2t / push log2(10) }NOT for xtndd_dbl
fmulp %st,%st(1) / z = x*log2(10) }NOT for xtndd_dbl
f2xm1 / 2**z - 1
fld1 / 1,2**z - 1
faddp %st,%st(1) / 2**z = 10**x
ret
.not_finite:
cmpl $0x7ff00000,%ecx / hi_32(|x|) > hi_32(INF)?
ja .NaN_or_pinf / if so, x is NaN
movl 4(%esp),%edx / edx <-- lo_32(x)
cmpl $0,%edx / lo_32(x) = 0?
jne .NaN_or_pinf / if not, x is NaN
movl 8(%esp),%eax / eax <-- hi_32(x)
andl $0x80000000,%eax / here, x is infinite, but +/-?
jz .NaN_or_pinf / branch if x = +INF
fldz / Here, x = -inf, so return 0
ret
.NaN_or_pinf:
/ Here, x = NaN or +inf, so load x and return immediately.
fldl 4(%esp)
fwait
ret
.align 4
SET_SIZE(exp10)