| Commit | Line | Data |
|---|
| 463ee0b2 |
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 | |
| 85e6fe83 |
10 | #include "config.h" |
| 463ee0b2 |
11 | #include "sdbm.h" |
| 12 | /* |
| 13 | * polynomial conversion ignoring overflows |
| 14 | * [this seems to work remarkably well, in fact better |
| 15 | * then the ndbm hash function. Replace at your own risk] |
| 16 | * use: 65599 nice. |
| 17 | * 65587 even better. |
| 18 | */ |
| 19 | long |
| f0f333f4 |
20 | sdbm_hash(register char *str, register int len) |
| 463ee0b2 |
21 | { |
| 22 | register unsigned long n = 0; |
| 23 | |
| 24 | #ifdef DUFF |
| 25 | |
| 26 | #define HASHC n = *str++ + 65599 * n |
| 27 | |
| 28 | if (len > 0) { |
| 29 | register int loop = (len + 8 - 1) >> 3; |
| 30 | |
| 31 | switch(len & (8 - 1)) { |
| 32 | case 0: do { |
| 33 | HASHC; case 7: HASHC; |
| 34 | case 6: HASHC; case 5: HASHC; |
| 35 | case 4: HASHC; case 3: HASHC; |
| 36 | case 2: HASHC; case 1: HASHC; |
| 37 | } while (--loop); |
| 38 | } |
| 39 | |
| 40 | } |
| 41 | #else |
| 42 | while (len--) |
| 43 | n = *str++ + 65599 * n; |
| 44 | #endif |
| 45 | return n; |
| 46 | } |
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