1/*	$NetBSD: e_exp.S,v 1.13 2008/06/23 00:12:04 christos Exp $	*/
2
3/*
4 * Copyright (c) 1993,94 Winning Strategies, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 *    must display the following acknowledgement:
17 *      This product includes software developed by Winning Strategies, Inc.
18 * 4. The name of the author may not be used to endorse or promote products
19 *    derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33/*
34 * Written by:
35 *	J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
36 */
37
38#include <machine/asm.h>
39
40#include "abi.h"
41
42RCSID("$NetBSD: e_exp.S,v 1.13 2008/06/23 00:12:04 christos Exp $")
43#if 0
44RCSID("$FreeBSD: src/lib/msun/i387/e_exp.S,v 1.8.2.1 2000/07/10 09:16:28 obrien Exp $")
45#endif
46
47/* e^x = 2^(x * log2(e)) */
48ENTRY(__ieee754_exp)
49	XMM_ONE_ARG_DOUBLE_PROLOGUE
50	/*
51	 * If x is +-Inf, then the subtraction would give Inf-Inf = NaN.
52	 * Avoid this.  Also avoid it if x is NaN for convenience.
53	 */
54	movl	ARG_DOUBLE_ONE_MSW, %eax
55	andl	$0x7fffffff, %eax
56	cmpl	$0x7ff00000, %eax
57	jae	x_Inf_or_NaN
58
59	fldl	ARG_DOUBLE_ONE
60
61	/*
62	 * Ensure that the rounding mode is to nearest (to give the smallest
63	 * possible fraction) and that the precision is as high as possible.
64	 * We may as well mask interrupts if we switch the mode.
65	 */
66#define CWSTORE_SAV ARG_DOUBLE_ONE_LSW /* XXX overwrites the argument */
67#define CWSTORE_TMP ARG_DOUBLE_ONE_MSW
68	fstcw	CWSTORE_SAV
69	movl	CWSTORE_SAV, %eax
70	andl	$0x0f00, %eax
71	cmpl	$0x0300, %eax		/* RC == 0 && PC == 3? */
72	je	1f			/* jump if mode is good */
73	movl	$0x137f, CWSTORE_TMP
74	fldcw	CWSTORE_TMP
751:
76	fldl2e
77	fmulp				/* x * log2(e) */
78	fst	%st(1)
79	frndint				/* int(x * log2(e)) */
80	fst	%st(2)
81	fsubrp				/* fract(x * log2(e)) */
82	f2xm1				/* 2^(fract(x * log2(e))) - 1 */
83	fld1
84	faddp				/* 2^(fract(x * log2(e))) */
85	fscale				/* e^x */
86	fstp	%st(1)
87	je	1f
88	fldcw	CWSTORE_SAV
891:
90	XMM_DOUBLE_EPILOGUE
91	ret
92x_Inf_or_NaN:
93	/*
94	 * Return 0 if x is -Inf.  Otherwise just return x, although the
95	 * C version would return (x + x) (Real Indefinite) if x is a NaN.
96	 */
97	cmpl	$0xfff00000, ARG_DOUBLE_ONE_MSW
98	jne	x_not_minus_Inf
99	cmpl	$0, ARG_DOUBLE_ONE_LSW
100	jne	x_not_minus_Inf
101	fldz
102	XMM_DOUBLE_EPILOGUE
103	ret
104
105x_not_minus_Inf:
106	fldl	ARG_DOUBLE_ONE
107	XMM_DOUBLE_EPILOGUE
108	ret
109