xref: /titanic_41/usr/src/lib/libm/common/R/scalbf.c (revision bb6fd8f9750a0c1d46a75c5bcc91952d3709334b)
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 __scalbf = scalbf
30 
31 #include "libm.h"
32 
33 float
34 scalbf(float x, float y) {
35 	int	ix, iy, hx, hy, n;
36 
37 	ix = *(int *)&x;
38 	iy = *(int *)&y;
39 	hx = ix & ~0x80000000;
40 	hy = iy & ~0x80000000;
41 
42 	if (hx > 0x7f800000 || hy >= 0x7f800000) {
43 		/* x is nan or y is inf or nan */
44 		return ((iy < 0)? x / -y : x * y);
45 	}
46 
47 	/* see if y is an integer without raising inexact */
48 	if (hy >= 0x4b000000) {
49 		/* |y| >= 2^23, so it must be an integer */
50 		n = (iy < 0)? -65000 : 65000;
51 	} else if (hy < 0x3f800000) {
52 		/* |y| < 1, so it must be zero or non-integer */
53 		return ((hy == 0)? x : (x - x) / (x - x));
54 	} else {
55 		if (hy & ((1 << (0x96 - (hy >> 23))) - 1))
56 			return ((y - y) / (y - y));
57 		n = (int)y;
58 	}
59 	return (scalbnf(x, n));
60 }
61