xref: /illumos-gate/usr/src/lib/libm/common/R/log1pf.c (revision ddc0e0b5)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
23  */
24 /*
25  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
26  * Use is subject to license terms.
27  */
28 
29 #pragma weak __log1pf = log1pf
30 
31 #include "libm.h"
32 
33 static const float zero = 0.0f;
34 
35 float
log1pf(float x)36 log1pf(float x) {
37 	int	ix;
38 
39 	ix = *(int *)&x;
40 	if (ix >= 0x7f800000) {
41 		/* x is +inf or nan */
42 		return (x * x);
43 	}
44 	if (ix < 0) {
45 		ix &= ~0x80000000;
46 		if (ix == 0x3f800000) /* x is -1 */
47 			return (x / zero);
48 		if (ix > 0x3f800000) /* x is < -1 or nan */
49 			return ((x * zero) / zero);
50 	}
51 	return ((float)log1p((double)x));
52 }
53