No puede seleccionar más de 25 temas
Los temas deben comenzar con una letra o número, pueden incluir guiones ('-') y pueden tener hasta 35 caracteres de largo.
45 líneas
958 B
45 líneas
958 B
// 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 leveldb {
|
|
|
|
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;
|
|
}
|
|
|
|
|
|
}
|