src/common/urand.c

#ifndef lint
static const char       RCSid[] = "$Id$";
#endif
/*
 * Anticorrelated random function due to Christophe Schlick
 */

/* ====================================================================
 * 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/>.
 */

#include  <stdlib.h>
#include  "random.h"

#undef initurand

#define  MAXORDER       (8*sizeof(unsigned short))

unsigned short  *urperm = NULL; /* urand() permutation */
int  urmask;            /* bits used in permutation */

int
initurand(size)         /* initialize urand() for size entries */
int  size;
{
        int  order, n;
        register int  i, offset;

        if (urperm != NULL)
                free((void *)urperm);
        if (--size <= 0) {
                urperm = NULL;
                urmask = 0;
                return(0);
        }
        for (i = 1; size >>= 1; i++)
                ;
        order = i>MAXORDER ? MAXORDER : i;
        urmask = (1<<i) - 1;
        urperm = (unsigned short *)malloc((urmask+1)*sizeof(unsigned short));
        if (urperm == NULL) {
                eputs("out of memory in initurand\n");
                quit(1);
        }
        urperm[0] = 0;
        for (n = 1, offset = 1; n <= order; n++, offset <<= 1)
                for (i = offset; i--; ) {
                        urperm[i] =
                        urperm[i+offset] = 2*urperm[i];
                        if (random() & 0x4000)
                                urperm[i]++;
                        else
                                urperm[i+offset]++;
                }
        return(1<<order);
}


int
ilhash(d, n)                    /* hash a set of integer values */
register int  *d;
register int  n;
{
        static int  tab[8] = {13623,353,1637,5831,2314,3887,5832,8737};
        register int  hval;

        hval = 0;
        while (n-- > 0)
                hval += *d++ * tab[n&7];
        return(hval);
}
Revision:	2.5
Committed:	Sat Feb 22 02:07:22 2003 UTC (21 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.4:	+66 -10 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
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.5	static const char RCSid[] = "$Id$";
3	greg	1.1	#endif
4			/*
5	greg	1.5	* Anticorrelated random function due to Christophe Schlick
6	greg	1.1	*/
7
8	greg	2.5	/* ====================================================================
9			* The Radiance Software License, Version 1.0
10			*
11			* Copyright (c) 1990 - 2002 The Regents of the University of California,
12			* through Lawrence Berkeley National Laboratory. All rights reserved.
13			*
14			* Redistribution and use in source and binary forms, with or without
15			* modification, are permitted provided that the following conditions
16			* are met:
17			*
18			* 1. Redistributions of source code must retain the above copyright
19			* notice, this list of conditions and the following disclaimer.
20			*
21			* 2. Redistributions in binary form must reproduce the above copyright
22			* notice, this list of conditions and the following disclaimer in
23			* the documentation and/or other materials provided with the
24			* distribution.
25			*
26			* 3. The end-user documentation included with the redistribution,
27			* if any, must include the following acknowledgment:
28			* "This product includes Radiance software
29			* (http://radsite.lbl.gov/)
30			* developed by the Lawrence Berkeley National Laboratory
31			* (http://www.lbl.gov/)."
32			* Alternately, this acknowledgment may appear in the software itself,
33			* if and wherever such third-party acknowledgments normally appear.
34			*
35			* 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
36			* and "The Regents of the University of California" must
37			* not be used to endorse or promote products derived from this
38			* software without prior written permission. For written
39			* permission, please contact [email protected].
40			*
41			* 5. Products derived from this software may not be called "Radiance",
42			* nor may "Radiance" appear in their name, without prior written
43			* permission of Lawrence Berkeley National Laboratory.
44			*
45			* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
46			* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
47			* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
48			* DISCLAIMED. IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
49			* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
50			* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
51			* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
52			* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
53			* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
54			* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
55			* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
56			* SUCH DAMAGE.
57			* ====================================================================
58			*
59			* This software consists of voluntary contributions made by many
60			* individuals on behalf of Lawrence Berkeley National Laboratory. For more
61			* information on Lawrence Berkeley National Laboratory, please see
62			* <http://www.lbl.gov/>.
63			*/
64
65			#include <stdlib.h>
66	greg	1.1	#include "random.h"
67
68	greg	2.5	#undef initurand
69	greg	1.1
70	gregl	2.4	#define MAXORDER (8*sizeof(unsigned short))
71
72			unsigned short urperm = NULL; / urand() permutation */
73	greg	1.1	int urmask; /* bits used in permutation */
74
75	gregl	2.3	int
76	greg	1.1	initurand(size) /* initialize urand() for size entries */
77			int size;
78			{
79			int order, n;
80			register int i, offset;
81
82	greg	2.2	if (urperm != NULL)
83	greg	2.5	free((void *)urperm);
84			if (--size <= 0) {
85			urperm = NULL;
86			urmask = 0;
87			return(0);
88			}
89	greg	1.1	for (i = 1; size >>= 1; i++)
90			;
91	gregl	2.4	order = i>MAXORDER ? MAXORDER : i;
92	greg	1.1	urmask = (1<<i) - 1;
93	gregl	2.4	urperm = (unsigned short )malloc((urmask+1)sizeof(unsigned short));
94	greg	1.1	if (urperm == NULL) {
95			eputs("out of memory in initurand\n");
96			quit(1);
97			}
98			urperm[0] = 0;
99			for (n = 1, offset = 1; n <= order; n++, offset <<= 1)
100			for (i = offset; i--; ) {
101			urperm[i] =
102			urperm[i+offset] = 2*urperm[i];
103			if (random() & 0x4000)
104			urperm[i]++;
105			else
106			urperm[i+offset]++;
107			}
108	gregl	2.3	return(1<<order);
109	greg	1.2	}
110
111
112			int
113	greg	1.3	ilhash(d, n) /* hash a set of integer values */
114	greg	1.2	register int *d;
115			register int n;
116			{
117			static int tab[8] = {13623,353,1637,5831,2314,3887,5832,8737};
118	greg	1.4	register int hval;
119	greg	1.2
120			hval = 0;
121			while (n-- > 0)
122			hval += d++ tab[n&7];
123	greg	1.3	return(hval);
124	greg	1.1	}