5 |
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#endif |
6 |
|
|
7 |
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/* |
8 |
< |
* Uncorrelated (anticorrelated) random function |
8 |
> |
* Anticorrelated random function due to Christophe Schlick |
9 |
|
*/ |
10 |
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|
11 |
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#include "random.h" |
16 |
|
|
17 |
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short *urperm; /* urand() permutation */ |
18 |
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int urmask; /* bits used in permutation */ |
19 |
– |
static int urorder; /* number of bits */ |
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|
20 |
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|
21 |
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initurand(size) /* initialize urand() for size entries */ |
48 |
|
|
49 |
|
|
50 |
|
int |
51 |
< |
urhash(d, n) /* hash a set of integer values */ |
51 |
> |
ilhash(d, n) /* hash a set of integer values */ |
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|
register int *d; |
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register int n; |
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{ |
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|
static int tab[8] = {13623,353,1637,5831,2314,3887,5832,8737}; |
56 |
< |
register unsigned hval; |
56 |
> |
register int hval; |
57 |
|
|
58 |
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hval = 0; |
59 |
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while (n-- > 0) |
60 |
|
hval += *d++ * tab[n&7]; |
61 |
< |
return(hval & urmask); |
61 |
> |
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); |
114 |
|
} |