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greg |
1.1 |
/* Copyright (c) 1991 Regents of the University of California */
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#ifndef lint
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static char SCCSid[] = "$SunId$ LBL";
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#endif
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/*
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greg |
1.5 |
* Anticorrelated random function due to Christophe Schlick
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greg |
1.1 |
*/
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#include "random.h"
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#define NULL 0
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extern char *malloc();
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short *urperm; /* urand() permutation */
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int urmask; /* bits used in permutation */
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initurand(size) /* initialize urand() for size entries */
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int size;
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{
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int order, n;
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register int i, offset;
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size--;
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for (i = 1; size >>= 1; i++)
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;
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order = i;
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urmask = (1<<i) - 1;
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urperm = (short *)malloc((urmask+1)*sizeof(short));
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if (urperm == NULL) {
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eputs("out of memory in initurand\n");
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quit(1);
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}
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urperm[0] = 0;
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for (n = 1, offset = 1; n <= order; n++, offset <<= 1)
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for (i = offset; i--; ) {
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urperm[i] =
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urperm[i+offset] = 2*urperm[i];
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if (random() & 0x4000)
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urperm[i]++;
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else
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urperm[i+offset]++;
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}
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greg |
1.2 |
}
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int
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greg |
1.3 |
ilhash(d, n) /* hash a set of integer values */
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greg |
1.2 |
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};
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greg |
1.4 |
register int hval;
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greg |
1.2 |
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hval = 0;
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while (n-- > 0)
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hval += *d++ * tab[n&7];
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greg |
1.3 |
return(hval);
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greg |
1.1 |
}
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greg |
1.6 |
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static char bctab[256] = {
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0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
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};
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#define NBITS 32
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#if NBITS==32
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#define bitcount(i) (bctab[(i)>>24&0xff]+bctab[(i)>>16&0xff]+ \
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bctab[(i)>>8&0xff]+bctab[(i)&0xff])
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#endif
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#if NBITS==16
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#define bitcount(i) (bctab[(i)>>8&0xff]+bctab[(i)&0xff])
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#endif
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int
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urind(s, i) /* compute i'th index from seed s */
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int s, i;
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{
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register int ss, k;
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int left;
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ss = s*1103515245 + 12345;
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left = 0;
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for (k = i/NBITS; k--; ) {
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left += bitcount(ss);
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ss = ss*1103515245 + 12345;
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}
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for (k = i&(NBITS-1); k--; ss >>= 1)
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left += ss & 1;
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if (ss & 1)
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return(s-left-1);
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return(s-left+i);
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}
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