1 /*
2 * sdbm - ndbm work-alike hashed database library
3 * based on Per-Aake Larson's Dynamic Hashing algorithms. BIT 18 (1978).
4 * author: oz@nexus.yorku.ca
5 * status: public domain. keep it that way.
6 *
7 * hashing routine
8 */
9
10 #include "sdbm.h"
11 /*
12 * polynomial conversion ignoring overflows
13 * [this seems to work remarkably well, in fact better
14 * then the ndbm hash function. Replace at your own risk]
15 * use: 65599 nice.
16 * 65587 even better.
17 */
18 long
sdbm_hash(str,len)19 sdbm_hash(str, len)
20 register char *str;
21 register int len;
22 {
23 register unsigned long n = 0;
24
25 #ifdef DUFF
26
27 #define HASHC n = *str++ + 65599 * n
28
29 if (len > 0) {
30 register int loop = (len + 8 - 1) >> 3;
31
32 switch(len & (8 - 1)) {
33 case 0: do {
34 HASHC; case 7: HASHC;
35 case 6: HASHC; case 5: HASHC;
36 case 4: HASHC; case 3: HASHC;
37 case 2: HASHC; case 1: HASHC;
38 } while (--loop);
39 }
40
41 }
42 #else
43 while (len--)
44 n = *str++ + 65599 * n;
45 #endif
46 return n;
47 }
48