xref: /illumos-gate/usr/src/lib/libm/common/R/log10f.c (revision 3ba944265c4ae1fcf23ef758537c2e4f4feec16e)
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 __log10f = log10f
30 
31 #include "libm.h"
32 
33 static const float zero = 0.0f, mone = -1.0f;
34 
35 float
36 log10f(float x) {
37 	int	hx, ix;
38 	float	w;
39 
40 	hx = *(int *)&x;
41 	ix = hx & ~0x80000000;
42 	if (ix > 0x7f800000)
43 		return (x * x);
44 	if (ix == 0x7f800000)
45 		return (x + x * x);
46 	if (ix == 0) {
47 		w = mone;
48 		return (w / zero);
49 	}
50 	if (hx < 0) {
51 		w = zero;
52 		return (w / zero);
53 	}
54 	return ((float)log10((double)x));
55 }
56