xref: /titanic_52/usr/src/lib/libm/i386/src/exp2f.s (revision ddc0e0b53c661f6e439e3b7072b3ef353eadb4af)
1*25c28e83SPiotr Jasiukajtis/*
2*25c28e83SPiotr Jasiukajtis * CDDL HEADER START
3*25c28e83SPiotr Jasiukajtis *
4*25c28e83SPiotr Jasiukajtis * The contents of this file are subject to the terms of the
5*25c28e83SPiotr Jasiukajtis * Common Development and Distribution License (the "License").
6*25c28e83SPiotr Jasiukajtis * You may not use this file except in compliance with the License.
7*25c28e83SPiotr Jasiukajtis *
8*25c28e83SPiotr Jasiukajtis * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9*25c28e83SPiotr Jasiukajtis * or http://www.opensolaris.org/os/licensing.
10*25c28e83SPiotr Jasiukajtis * See the License for the specific language governing permissions
11*25c28e83SPiotr Jasiukajtis * and limitations under the License.
12*25c28e83SPiotr Jasiukajtis *
13*25c28e83SPiotr Jasiukajtis * When distributing Covered Code, include this CDDL HEADER in each
14*25c28e83SPiotr Jasiukajtis * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15*25c28e83SPiotr Jasiukajtis * If applicable, add the following below this CDDL HEADER, with the
16*25c28e83SPiotr Jasiukajtis * fields enclosed by brackets "[]" replaced with your own identifying
17*25c28e83SPiotr Jasiukajtis * information: Portions Copyright [yyyy] [name of copyright owner]
18*25c28e83SPiotr Jasiukajtis *
19*25c28e83SPiotr Jasiukajtis * CDDL HEADER END
20*25c28e83SPiotr Jasiukajtis */
21*25c28e83SPiotr Jasiukajtis/*
22*25c28e83SPiotr Jasiukajtis * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
23*25c28e83SPiotr Jasiukajtis */
24*25c28e83SPiotr Jasiukajtis/*
25*25c28e83SPiotr Jasiukajtis * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
26*25c28e83SPiotr Jasiukajtis * Use is subject to license terms.
27*25c28e83SPiotr Jasiukajtis */
28*25c28e83SPiotr Jasiukajtis
29*25c28e83SPiotr Jasiukajtis        .file "exp2f.s"
30*25c28e83SPiotr Jasiukajtis
31*25c28e83SPiotr Jasiukajtis#include "libm.h"
32*25c28e83SPiotr JasiukajtisLIBM_ANSI_PRAGMA_WEAK(exp2f,function)
33*25c28e83SPiotr Jasiukajtis
34*25c28e83SPiotr Jasiukajtis	ENTRY(exp2f)
35*25c28e83SPiotr Jasiukajtis	movl	4(%esp),%ecx		/ ecx <-- x
36*25c28e83SPiotr Jasiukajtis	andl	$0x7fffffff,%ecx	/ ecx <-- |x|
37*25c28e83SPiotr Jasiukajtis	cmpl	$0x3f800000,%ecx	/ Is |x| <= 1?
38*25c28e83SPiotr Jasiukajtis	jbe	.shortcut		/ If so, take a shortcut.
39*25c28e83SPiotr Jasiukajtis	cmpl	$0x7f800000,%ecx	/ |x| >= INF?
40*25c28e83SPiotr Jasiukajtis	jae	.not_finite		/ if so, x is not finite
41*25c28e83SPiotr Jasiukajtis	flds	4(%esp)			/ push arg
42*25c28e83SPiotr Jasiukajtis	fld	%st(0)			/ duplicate stack top
43*25c28e83SPiotr Jasiukajtis	frndint				/ [x],x
44*25c28e83SPiotr Jasiukajtis	fucom				/ x integral?
45*25c28e83SPiotr Jasiukajtis	fstsw	%ax
46*25c28e83SPiotr Jasiukajtis	sahf
47*25c28e83SPiotr Jasiukajtis	je      .x_integral		/ branch if x integral
48*25c28e83SPiotr Jasiukajtis	fxch				/ x, [x]
49*25c28e83SPiotr Jasiukajtis	fsub	%st(1),%st		/ x-[x], [x]
50*25c28e83SPiotr Jasiukajtis	f2xm1				/ 2**(x-[x])-1, [x]
51*25c28e83SPiotr Jasiukajtis	fld1				/ 1,2**(x-[x])-1, [x]
52*25c28e83SPiotr Jasiukajtis	faddp	%st,%st(1)		/ 2**(x-[x]), [x]
53*25c28e83SPiotr Jasiukajtis	fscale				/ 2**x = 2**(arg), [x]
54*25c28e83SPiotr Jasiukajtis	fstp	%st(1)
55*25c28e83SPiotr Jasiukajtis	ret
56*25c28e83SPiotr Jasiukajtis
57*25c28e83SPiotr Jasiukajtis.x_integral:				/ here, x is integral
58*25c28e83SPiotr Jasiukajtis	fstp	%st(0)			/ ,x
59*25c28e83SPiotr Jasiukajtis	fld1				/ 1 = 2**0, x
60*25c28e83SPiotr Jasiukajtis	fscale				/ 2**(0 + x) = 2**x, x
61*25c28e83SPiotr Jasiukajtis	fstp	%st(1)			/ 2**x
62*25c28e83SPiotr Jasiukajtis	ret
63*25c28e83SPiotr Jasiukajtis
64*25c28e83SPiotr Jasiukajtis.shortcut:
65*25c28e83SPiotr Jasiukajtis	/ Here, |x| <= 1,
66*25c28e83SPiotr Jasiukajtis	/ whence x is in f2xm1's domain.
67*25c28e83SPiotr Jasiukajtis	flds	4(%esp)			/ push x
68*25c28e83SPiotr Jasiukajtis	f2xm1				/ 2**x - 1
69*25c28e83SPiotr Jasiukajtis	fld1				/ 1,2**x - 1
70*25c28e83SPiotr Jasiukajtis	faddp	%st,%st(1)		/ 2**x
71*25c28e83SPiotr Jasiukajtis	ret
72*25c28e83SPiotr Jasiukajtis
73*25c28e83SPiotr Jasiukajtis.not_finite:
74*25c28e83SPiotr Jasiukajtis	ja	.NaN_or_pinf		/ branch if x is NaN
75*25c28e83SPiotr Jasiukajtis	movl	4(%esp),%eax		/ eax <-- x
76*25c28e83SPiotr Jasiukajtis	andl	$0x80000000,%eax	/ here, x is infinite, but +/-?
77*25c28e83SPiotr Jasiukajtis	jz	.NaN_or_pinf		/ branch if x = +INF
78*25c28e83SPiotr Jasiukajtis	fldz				/ Here, x = -inf, so return 0
79*25c28e83SPiotr Jasiukajtis	ret
80*25c28e83SPiotr Jasiukajtis
81*25c28e83SPiotr Jasiukajtis.NaN_or_pinf:
82*25c28e83SPiotr Jasiukajtis	/ Here, x = NaN or +inf, so load x and return immediately.
83*25c28e83SPiotr Jasiukajtis	flds	4(%esp)
84*25c28e83SPiotr Jasiukajtis	fwait
85*25c28e83SPiotr Jasiukajtis	ret
86*25c28e83SPiotr Jasiukajtis	.align	4
87*25c28e83SPiotr Jasiukajtis	SET_SIZE(exp2f)
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