src/common/urand.c

#ifndef lint
static const char       RCSid[] = "$Id: urand.c,v 2.6 2003/02/25 02:47:22 greg Exp $";
#endif
/*
 * Anticorrelated random function due to Christophe Schlick
 */

#include "copyright.h"

#include  <stdlib.h>

#include  "standard.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:	2.7
Committed:	Sat Jun 7 12:50:21 2003 UTC (20 years, 10 months ago) by schorsch
Content type:	text/plain
Branch:	MAIN
Changes since 2.6:	+3 -1 lines
Log Message:	Various small changes to reduce compile warnings/errors on Windows.
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	schorsch	2.7	static const char RCSid[] = "$Id: urand.c,v 2.6 2003/02/25 02:47:22 greg Exp $";
3	greg	1.1	#endif
4			/*
5	greg	1.5	* Anticorrelated random function due to Christophe Schlick
6	greg	1.1	*/
7
8	greg	2.6	#include "copyright.h"
9	greg	2.5
10			#include <stdlib.h>
11	schorsch	2.7
12			#include "standard.h"
13	greg	1.1	#include "random.h"
14
15	greg	2.5	#undef initurand
16	greg	1.1
17	gregl	2.4	#define MAXORDER (8*sizeof(unsigned short))
18
19			unsigned short urperm = NULL; / urand() permutation */
20	greg	1.1	int urmask; /* bits used in permutation */
21
22	gregl	2.3	int
23	greg	1.1	initurand(size) /* initialize urand() for size entries */
24			int size;
25			{
26			int order, n;
27			register int i, offset;
28
29	greg	2.2	if (urperm != NULL)
30	greg	2.5	free((void *)urperm);
31			if (--size <= 0) {
32			urperm = NULL;
33			urmask = 0;
34			return(0);
35			}
36	greg	1.1	for (i = 1; size >>= 1; i++)
37			;
38	gregl	2.4	order = i>MAXORDER ? MAXORDER : i;
39	greg	1.1	urmask = (1<<i) - 1;
40	gregl	2.4	urperm = (unsigned short )malloc((urmask+1)sizeof(unsigned short));
41	greg	1.1	if (urperm == NULL) {
42			eputs("out of memory in initurand\n");
43			quit(1);
44			}
45			urperm[0] = 0;
46			for (n = 1, offset = 1; n <= order; n++, offset <<= 1)
47			for (i = offset; i--; ) {
48			urperm[i] =
49			urperm[i+offset] = 2*urperm[i];
50			if (random() & 0x4000)
51			urperm[i]++;
52			else
53			urperm[i+offset]++;
54			}
55	gregl	2.3	return(1<<order);
56	greg	1.2	}
57
58
59			int
60	greg	1.3	ilhash(d, n) /* hash a set of integer values */
61	greg	1.2	register int *d;
62			register int n;
63			{
64			static int tab[8] = {13623,353,1637,5831,2314,3887,5832,8737};
65	greg	1.4	register int hval;
66	greg	1.2
67			hval = 0;
68			while (n-- > 0)
69			hval += d++ tab[n&7];
70	greg	1.3	return(hval);
71	greg	1.1	}