/* 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; }