Revision 16f1aa7b2d0b5f44397810faeed9fae278d89bc6 authored by Igor Canadi on 30 April 2014, 18:38:01 UTC, committed by Igor Canadi on 30 April 2014, 18:38:01 UTC
1 parent df70047
hash.cc
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include <string.h>
#include "util/coding.h"
#include "util/hash.h"
namespace rocksdb {
uint32_t Hash(const char* data, size_t n, uint32_t seed) {
// Similar to murmur hash
const uint32_t m = 0xc6a4a793;
const uint32_t r = 24;
const char* limit = data + n;
uint32_t h = seed ^ (n * m);
// Pick up four bytes at a time
while (data + 4 <= limit) {
uint32_t w = DecodeFixed32(data);
data += 4;
h += w;
h *= m;
h ^= (h >> 16);
}
// Pick up remaining bytes
switch (limit - data) {
case 3:
h += data[2] << 16;
// fall through
case 2:
h += data[1] << 8;
// fall through
case 1:
h += data[0];
h *= m;
h ^= (h >> r);
break;
}
return h;
}
} // namespace rocksdb
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