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root/Development/ray/src/common/urand.c

Comparing ray/src/common/urand.c (file contents):
Revision 1.3 by greg, Tue May 21 11:01:00 1991 UTC vs.
Revision 2.11 by greg, Wed May 27 08:42:06 2015 UTC

#	Line 1 | Line 1
1	–	/* Copyright (c) 1991 Regents of the University of California */
2	–
1		#ifndef lint
2	<	static char SCCSid[] = "$SunId$ LBL";
2	>	static const char       RCSid[] = "$Id$";
3		#endif
6	–
4		/*
5	<	* Uncorrelated (anticorrelated) random function
5	>	* Anticorrelated random function due to Christophe Schlick
6		*/
7
8	+	#include "copyright.h"
9	+
10	+	#include  "standard.h"
11		#include  "random.h"
12
13	<	#define  NULL           0
13	>	#undef initurand
14
15	<	extern char  *malloc();
15	>	#define  MAXORDER       (8*sizeof(unsigned short))
16
17	<	short  *urperm;         /* urand() permutation */
18	<	int  urmask;            /* bits used in permutation */
17	>	static unsigned short  empty_tab = 0;
18
19	+	unsigned short  *urperm = &empty_tab;   /* urand() permutation */
20	+	int  urmask = 0;                        /* bits used in permutation */
21
22	<	initurand(size)         /* initialize urand() for size entries */
23	<	int  size;
22	>
23	>	int
24	>	initurand(                      /* initialize urand() for size entries */
25	>	int  size
26	>	)
27		{
28		int  order, n;
29	<	register int  i, offset;
29	>	int  i, offset;
30
31	<	size--;
32	<	for (i = 1; size >>= 1; i++)
33	<	;
31	>	if ((urperm != NULL) & (urperm != &empty_tab))
32	>	free((void *)urperm);
33	>	if (--size <= 0) {
34	>	empty_tab = 0;
35	>	urperm = &empty_tab;
36	>	urmask = 0;
37	>	return(0);
38	>	}
39	>	for (i = 1; (size >>= 1); i++)
40	>	if (i == MAXORDER)
41	>	break;
42		order = i;
43	<	urmask = (1<<i) - 1;
44	<	urperm = (short *)malloc((urmask+1)*sizeof(short));
43	>	urmask = (1<<order) - 1;
44	>	urperm = (unsigned short *)malloc((urmask+1)*sizeof(unsigned short));
45		if (urperm == NULL) {
46		eputs("out of memory in initurand\n");
47		quit(1);
#	Line 37 | Line 49 | int  size;
49		urperm[0] = 0;
50		for (n = 1, offset = 1; n <= order; n++, offset <<= 1)
51		for (i = offset; i--; ) {
52	<	urperm[i] =
41	<	urperm[i+offset] = 2*urperm[i];
52	>	urperm[i+offset] = urperm[i] <<= 1;
53		if (random() & 0x4000)
54		urperm[i]++;
55		else
56		urperm[i+offset]++;
57		}
58	+	return(urmask+1);
59		}
60
61
62		int
63	<	ilhash(d, n)                    /* hash a set of integer values */
64	<	register int  *d;
65	<	register int  n;
63	>	ilhash(                         /* hash a set of integer values */
64	>	int  *d,
65	>	int  n
66	>	)
67		{
68	<	static int  tab[8] = {13623,353,1637,5831,2314,3887,5832,8737};
69	<	register unsigned  hval;
68	>	static int  tab[8] = {103699,96289,73771,65203,81119,87037,92051,98899};
69	>	int  hval;
70
71		hval = 0;
72		while (n-- > 0)
73	<	hval += *d++ * tab[n&7];
74	<	return(hval);
73	>	hval ^= *d++ * tab[n&7];
74	>	return(hval & 0x7fffffff);
75		}

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