xref: /titanic_41/usr/src/lib/libbc/libc/gen/common/frexp.c (revision 74e20cfe817b82802b16fac8690dadcda76f54f5)
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, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 #pragma ident	"%Z%%M%	%I%	%E% SMI"  /* from UCB 5.2 3/9/86 */
23 
24 /*
25  * the call
26  *	x = frexp(arg,&exp);
27  * must return a double fp quantity x which is <1.0
28  * and the corresponding binary exponent "exp".
29  * such that
30  *	arg = x*2^exp
31  */
32 double
33 frexp(x, i)
34 	double x;
35 	int *i;
36 {
37 	int neg, j;
38 
39 	j = 0;
40 	neg = 0;
41 	if (x<0) {
42 		x = -x;
43 		neg = 1;
44 	}
45 	if (x>=1.0)
46 		while (x>=1.0) {
47 			j = j+1;
48 			x = x/2;
49 		}
50 	else if (x < 0.5 && x != 0.0)
51 		while(x<0.5) {
52 			j = j-1;
53 			x = 2*x;
54 		}
55 	*i = j;
56 	if(neg)
57 		x = -x;
58 	return (x);
59 }
60