xref: /titanic_41/usr/src/lib/libm/common/LD/scalbl.c (revision 4f4499478f0aa55fc93bcd8030ba3d128663ae70)
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 /*
23  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
24  */
25 /*
26  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
27  * Use is subject to license terms.
28  */
29 
30 #pragma weak scalbl = __scalbl
31 
32 /*
33  * scalbl(x,n): return x * 2**n by manipulating exponent.
34  */
35 
36 #include "libm.h"
37 #include "longdouble.h"
38 
39 #include <sys/isa_defs.h>
40 
41 long double
42 scalbl(long double x, long double fn) {
43 	int *py = (int *) &fn, n;
44 	long double z;
45 
46 	if (isnanl(x) || isnanl(fn))
47 		return x * fn;
48 
49 	/* fn is +/-Inf */
50 #if defined(_BIG_ENDIAN)
51 	if ((py[0] & 0x7fff0000) == 0x7fff0000) {
52 		if ((py[0] & 0x80000000) != 0)
53 #else
54 	if ((py[2] & 0x7fff) == 0x7fff) {
55 		if ((py[2] & 0x8000) != 0)
56 #endif
57 			return x / (-fn);
58 		else
59 			return x * fn;
60 	}
61 	if (rintl(fn) != fn)
62 		return (fn - fn) / (fn - fn);
63 	if (fn > 65000.0L)
64 		z = scalbnl(x, 65000);
65 	else if (-fn > 65000.0L)
66 		z = scalbnl(x, -65000);
67 	else {
68 		n = (int) fn;
69 		z = scalbnl(x, n);
70 	}
71 	return z;
72 }
73