| /* Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| /* |
| * sdbm - ndbm work-alike hashed database library |
| * based on Per-Aake Larson's Dynamic Hashing algorithms. BIT 18 (1978). |
| * author: oz@nexus.yorku.ca |
| * status: ex-public domain. keep it that way. |
| * |
| * hashing routine |
| */ |
| |
| #include "apr_sdbm.h" |
| #include "sdbm_private.h" |
| |
| /* |
| * polynomial conversion ignoring overflows |
| * [this seems to work remarkably well, in fact better |
| * then the ndbm hash function. Replace at your own risk] |
| * use: 65599 nice. |
| * 65587 even better. |
| */ |
| long sdbm_hash(const char *str, int len) |
| { |
| register unsigned long n = 0; |
| |
| #define DUFF /* go ahead and use the loop-unrolled version */ |
| #ifdef DUFF |
| |
| #define HASHC n = *str++ + 65599 * n |
| |
| if (len > 0) { |
| register int loop = (len + 8 - 1) >> 3; |
| |
| switch(len & (8 - 1)) { |
| case 0: do { |
| HASHC; case 7: HASHC; |
| case 6: HASHC; case 5: HASHC; |
| case 4: HASHC; case 3: HASHC; |
| case 2: HASHC; case 1: HASHC; |
| } while (--loop); |
| } |
| |
| } |
| #else |
| while (len--) |
| n = *str++ + 65599 * n; |
| #endif |
| return n; |
| } |