1/*	$OpenBSD: e_exp.S,v 1.5 2008/09/07 20:36:08 martynas Exp $	*/
2/*	$NetBSD: e_exp.S,v 1.12 2002/02/27 16:32:46 christos Exp $	*/
3
4/*
5 * Copyright (c) 1993,94 Winning Strategies, Inc.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *      This product includes software developed by Winning Strategies, Inc.
19 * 4. The name of the author may not be used to endorse or promote products
20 *    derived from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34/*
35 * Written by:
36 *	J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
37 */
38
39#include <machine/asm.h>
40
41#include "abi.h"
42
43/* e^x = 2^(x * log2(e)) */
44ENTRY(exp)
45	XMM_ONE_ARG_DOUBLE_PROLOGUE
46	/*
47	 * If x is +-Inf, then the subtraction would give Inf-Inf = NaN.
48	 * Avoid this.  Also avoid it if x is NaN for convenience.
49	 */
50	movl	-4(%rsp),%eax
51	andl	$0x7fffffff,%eax
52	cmpl	$0x7ff00000,%eax
53	jae	x_Inf_or_NaN
54
55	fldl	ARG_DOUBLE_ONE
56
57	/*
58	 * Ensure that the rounding mode is to nearest (to give the smallest
59	 * possible fraction) and that the precision is as high as possible.
60	 * We may as well mask interrupts if we switch the mode.
61	 */
62	fstcw	-8(%rsp)
63	movl	-8(%rsp),%eax
64	andl	$0x0300,%eax
65	cmpl	$0x0300,%eax		/* RC == 0 && PC == 3? */
66	je	1f			/* jump if mode is good */
67	movl	$0x137f,-4(%rsp)
68	fldcw	-4(%rsp)
691:
70	fldl2e
71	fmulp				/* x * log2(e) */
72	fst	%st(1)
73	frndint				/* int(x * log2(e)) */
74	fst	%st(2)
75	fsubrp				/* fract(x * log2(e)) */
76	f2xm1				/* 2^(fract(x * log2(e))) - 1 */
77	fld1
78	faddp				/* 2^(fract(x * log2(e))) */
79	fscale				/* e^x */
80	fstp	%st(1)
81	je	1f
82	fldcw	-8(%rsp)
831:
84	XMM_DOUBLE_EPILOGUE
85	ret
86
87x_Inf_or_NaN:
88	/*
89	 * Return 0 if x is -Inf.  Otherwise just return x, although the
90	 * C version would return (x + x) (Real Indefinite) if x is a NaN.
91	 */
92	cmpl	$0xfff00000,-4(%rsp)
93	jne	x_not_minus_Inf
94	cmpl	$0,-8(%rsp)
95	jne	x_not_minus_Inf
96	xorpd	%xmm0,%xmm0
97	ret
98
99x_not_minus_Inf:
100	movsd	ARG_DOUBLE_ONE,%xmm0
101	ret
102END(exp)
103
104	.section .note.GNU-stack,"",%progbits
105