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/** @file hash.h */
/* Copyright 2009 10gen Inc.
*
* Licensed 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.
*/
#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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