ViewVC Help
View File | Revision Log | Show Annotations | Download File | Root Listing
root/radiance/ray/src/common/urand.c
(Generate patch)

Comparing ray/src/common/urand.c (file contents):
Revision 1.6 by greg, Thu Jul 11 16:25:58 1991 UTC vs.
Revision 2.4 by gregl, Mon Jan 5 16:47:37 1998 UTC

# Line 1 | Line 1
1 < /* Copyright (c) 1991 Regents of the University of California */
1 > /* Copyright (c) 1998 Silicon Graphics, Inc. */
2  
3   #ifndef lint
4 < static char SCCSid[] = "$SunId$ LBL";
4 > static char SCCSid[] = "$SunId$ SGI";
5   #endif
6  
7   /*
# Line 12 | Line 12 | static char SCCSid[] = "$SunId$ LBL";
12  
13   #define  NULL           0
14  
15 + #define  MAXORDER       (8*sizeof(unsigned short))
16 +
17   extern char  *malloc();
18  
19 < short  *urperm;         /* urand() permutation */
19 > unsigned short  *urperm = NULL; /* urand() permutation */
20   int  urmask;            /* bits used in permutation */
21  
22  
23 + int
24   initurand(size)         /* initialize urand() for size entries */
25   int  size;
26   {
27          int  order, n;
28          register int  i, offset;
29  
30 +        if (urperm != NULL)
31 +                free((char *)urperm);
32          size--;
33          for (i = 1; size >>= 1; i++)
34                  ;
35 <        order = i;
35 >        order = i>MAXORDER ? MAXORDER : i;
36          urmask = (1<<i) - 1;
37 <        urperm = (short *)malloc((urmask+1)*sizeof(short));
37 >        urperm = (unsigned short *)malloc((urmask+1)*sizeof(unsigned short));
38          if (urperm == NULL) {
39                  eputs("out of memory in initurand\n");
40                  quit(1);
# Line 44 | Line 49 | int  size;
49                          else
50                                  urperm[i+offset]++;
51                  }
52 +        return(1<<order);
53   }
54  
55  
# Line 59 | Line 65 | register int  n;
65          while (n-- > 0)
66                  hval += *d++ * tab[n&7];
67          return(hval);
62 }
63
64
65 static char  bctab[256] = {
66                0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
67                1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
68                1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
69                2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
70                1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
71                2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
72                2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
73                3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
74                1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
75                2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
76                2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
77                3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
78                2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
79                3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
80                3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
81                4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
82        };
83
84
85 #define NBITS           32
86
87 #if NBITS==32
88 #define  bitcount(i)    (bctab[(i)>>24&0xff]+bctab[(i)>>16&0xff]+ \
89                                bctab[(i)>>8&0xff]+bctab[(i)&0xff])
90 #endif
91 #if  NBITS==16
92 #define  bitcount(i)    (bctab[(i)>>8&0xff]+bctab[(i)&0xff])
93 #endif
94
95
96 int
97 urind(s, i)                     /* compute i'th index from seed s */
98 int     s, i;
99 {
100        register int  ss, k;
101        int  left;
102
103        ss = s*1103515245 + 12345;
104        left = 0;
105        for (k = i/NBITS; k--; ) {
106                left += bitcount(ss);
107                ss = ss*1103515245 + 12345;
108        }
109        for (k = i&(NBITS-1); k--; ss >>= 1)
110                left += ss & 1;
111        if (ss & 1)
112                return(s-left-1);
113        return(s-left+i);
68   }

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines