mongodb: hash.h Source File

00001 
00003 /*    Copyright 2009 10gen Inc.
00004  *
00005  *    Licensed under the Apache License, Version 2.0 (the "License");
00006  *    you may not use this file except in compliance with the License.
00007  *    You may obtain a copy of the License at
00008  *
00009  *    http://www.apache.org/licenses/LICENSE-2.0
00010  *
00011  *    Unless required by applicable law or agreed to in writing, software
00012  *    distributed under the License is distributed on an "AS IS" BASIS,
00013  *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00014  *    See the License for the specific language governing permissions and
00015  *    limitations under the License.
00016  */
00017 
00018 #pragma once
00019 
00020 namespace mongoutils {
00021 
00027     inline unsigned hashPointer(void *v) {
00028         unsigned x = 0;
00029         unsigned char *p = (unsigned char *) &v;
00030         for( unsigned i = 0; i < sizeof(void*); i++ ) {
00031             x = x * 131 + p[i];
00032         }
00033         return x;
00034     }
00035 
00036     inline unsigned hash(unsigned u) {
00037         unsigned char *p = (unsigned char *) &u;
00038         return (((((p[3] * 131) + p[2]) * 131) + p[1]) * 131) + p[0];
00039     }
00040 
00041 }