src/common/urand.c

/* Copyright (c) 1997 Silicon Graphics, Inc. */

#ifndef lint
static char SCCSid[] = "$SunId$ SGI";
#endif

/*
 * Anticorrelated random function due to Christophe Schlick
 */

#include  "random.h"

#define  NULL           0

extern char  *malloc();

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((char *)urperm);
        size--;
        for (i = 1; size >>= 1; i++)
                ;
        order = i;
        urmask = (1<<i) - 1;
        urperm = (short *)malloc((urmask+1)*sizeof(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:	2.3
Committed:	Mon Dec 1 09:55:00 1997 UTC (26 years, 5 months ago) by gregl
Content type:	text/plain
Branch:	MAIN
Changes since 2.2:	+4 -2 lines
Log Message:	added define to eliminate initurand() reference for -DMC
#	User	Rev	Content
1	gregl	2.3	/* Copyright (c) 1997 Silicon Graphics, Inc. */
2	greg	1.1
3			#ifndef lint
4	gregl	2.3	static char SCCSid[] = "$SunId$ SGI";
5	greg	1.1	#endif
6
7			/*
8	greg	1.5	* Anticorrelated random function due to Christophe Schlick
9	greg	1.1	*/
10
11			#include "random.h"
12
13			#define NULL 0
14
15			extern char *malloc();
16
17	greg	2.2	short urperm = NULL; / urand() permutation */
18	greg	1.1	int urmask; /* bits used in permutation */
19
20
21	gregl	2.3	int
22	greg	1.1	initurand(size) /* initialize urand() for size entries */
23			int size;
24			{
25			int order, n;
26			register int i, offset;
27
28	greg	2.2	if (urperm != NULL)
29			free((char *)urperm);
30	greg	1.1	size--;
31			for (i = 1; size >>= 1; i++)
32			;
33			order = i;
34			urmask = (1<<i) - 1;
35			urperm = (short )malloc((urmask+1)sizeof(short));
36			if (urperm == NULL) {
37			eputs("out of memory in initurand\n");
38			quit(1);
39			}
40			urperm[0] = 0;
41			for (n = 1, offset = 1; n <= order; n++, offset <<= 1)
42			for (i = offset; i--; ) {
43			urperm[i] =
44			urperm[i+offset] = 2*urperm[i];
45			if (random() & 0x4000)
46			urperm[i]++;
47			else
48			urperm[i+offset]++;
49			}
50	gregl	2.3	return(1<<order);
51	greg	1.2	}
52
53
54			int
55	greg	1.3	ilhash(d, n) /* hash a set of integer values */
56	greg	1.2	register int *d;
57			register int n;
58			{
59			static int tab[8] = {13623,353,1637,5831,2314,3887,5832,8737};
60	greg	1.4	register int hval;
61	greg	1.2
62			hval = 0;
63			while (n-- > 0)
64			hval += d++ tab[n&7];
65	greg	1.3	return(hval);
66	greg	1.1	}