src/common/frexp.c

#ifndef lint
static const char       RCSid[] = "$Id$";
#endif
/* ====================================================================
 * The Radiance Software License, Version 1.0
 *
 * Copyright (c) 1990 - 2002 The Regents of the University of California,
 * through Lawrence Berkeley National Laboratory.   All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *         notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *           if any, must include the following acknowledgment:
 *             "This product includes Radiance software
 *                 (http://radsite.lbl.gov/)
 *                 developed by the Lawrence Berkeley National Laboratory
 *               (http://www.lbl.gov/)."
 *       Alternately, this acknowledgment may appear in the software itself,
 *       if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
 *       and "The Regents of the University of California" must
 *       not be used to endorse or promote products derived from this
 *       software without prior written permission. For written
 *       permission, please contact [email protected].
 *
 * 5. Products derived from this software may not be called "Radiance",
 *       nor may "Radiance" appear in their name, without prior written
 *       permission of Lawrence Berkeley National Laboratory.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.   IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Lawrence Berkeley National Laboratory.   For more
 * information on Lawrence Berkeley National Laboratory, please see
 * <http://www.lbl.gov/>.
 */

frexp(x, ip)            /* call it paranoia, I've seen the lib version */
register double  x;
int  *ip;
{
        int  neg;
        register int  i;

        if (neg = (x < 0.0))
                x = -x;
        else if (x == 0.0) {
                *ip = 0;
                return(0.0);
        }
        if (x < 0.5)
                for (i = 0; x < 0.5; i--)
                        x *= 2.0;
        else
                for (i = 0; x >= 1.0; i++)
                        x /= 2.0;
        *ip = i;
        if (neg)
                return(-x);
        else
                return(x);
}
Revision:	1.2
Committed:	Sat Feb 22 02:07:22 2003 UTC (21 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.1:	+57 -2 lines
Log Message:	Changes and check-in for 3.5 release Includes new source files and modifications not recorded for many years See ray/doc/notes/ReleaseNotes for notes between 3.1 and 3.5 release
#	Content
1	#ifndef lint
2	static const char RCSid[] = "$Id$";
3	#endif
4	/* ====================================================================
5	* The Radiance Software License, Version 1.0
6	*
7	* Copyright (c) 1990 - 2002 The Regents of the University of California,
8	* through Lawrence Berkeley National Laboratory. All rights reserved.
9	*
10	* Redistribution and use in source and binary forms, with or without
11	* modification, are permitted provided that the following conditions
12	* are met:
13	*
14	* 1. Redistributions of source code must retain the above copyright
15	* notice, this list of conditions and the following disclaimer.
16	*
17	* 2. Redistributions in binary form must reproduce the above copyright
18	* notice, this list of conditions and the following disclaimer in
19	* the documentation and/or other materials provided with the
20	* distribution.
21	*
22	* 3. The end-user documentation included with the redistribution,
23	* if any, must include the following acknowledgment:
24	* "This product includes Radiance software
25	* (http://radsite.lbl.gov/)
26	* developed by the Lawrence Berkeley National Laboratory
27	* (http://www.lbl.gov/)."
28	* Alternately, this acknowledgment may appear in the software itself,
29	* if and wherever such third-party acknowledgments normally appear.
30	*
31	* 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
32	* and "The Regents of the University of California" must
33	* not be used to endorse or promote products derived from this
34	* software without prior written permission. For written
35	* permission, please contact [email protected].
36	*
37	* 5. Products derived from this software may not be called "Radiance",
38	* nor may "Radiance" appear in their name, without prior written
39	* permission of Lawrence Berkeley National Laboratory.
40	*
41	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
42	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
43	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
44	* DISCLAIMED. IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
45	* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
46	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
47	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
48	* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
49	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
50	* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
51	* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52	* SUCH DAMAGE.
53	* ====================================================================
54	*
55	* This software consists of voluntary contributions made by many
56	* individuals on behalf of Lawrence Berkeley National Laboratory. For more
57	* information on Lawrence Berkeley National Laboratory, please see
58	* <http://www.lbl.gov/>.
59	*/
60
61	frexp(x, ip) /* call it paranoia, I've seen the lib version */
62	register double x;
63	int *ip;
64	{
65	int neg;
66	register int i;
67
68	if (neg = (x < 0.0))
69	x = -x;
70	else if (x == 0.0) {
71	*ip = 0;
72	return(0.0);
73	}
74	if (x < 0.5)
75	for (i = 0; x < 0.5; i--)
76	x *= 2.0;
77	else
78	for (i = 0; x >= 1.0; i++)
79	x /= 2.0;
80	*ip = i;
81	if (neg)
82	return(-x);
83	else
84	return(x);
85	}