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/** @file hash.h */
/* Copyright 2009 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects
* for all of the code used other than as permitted herein. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you do not
* wish to do so, delete this exception statement from your version. If you
* delete this exception statement from all source files in the program,
* then also delete it in the license file.
*/
#pragma once
namespace mongoutils {
/** @return hash of a pointer to an unsigned. so you get a 32 bit hash out, regardless of whether
pointers are 32 or 64 bit on the particular platform.
is there a faster way to impl this that hashes just as well?
*/
inline unsigned hashPointer(void *v) {
unsigned x = 0;
unsigned char *p = (unsigned char *) &v;
for( unsigned i = 0; i < sizeof(void*); i++ ) {
x = x * 131 + p[i];
}
return x;
}
inline unsigned hash(unsigned u) {
unsigned char *p = (unsigned char *) &u;
return (((((p[3] * 131) + p[2]) * 131) + p[1]) * 131) + p[0];
}
}
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