You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
108 lines
2.9 KiB
108 lines
2.9 KiB
/*
|
|
* Copyright (C) 2018 The Android Open Source Project
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
#ifndef ART_LIBARTBASE_BASE_DATA_HASH_H_
|
|
#define ART_LIBARTBASE_BASE_DATA_HASH_H_
|
|
|
|
#include "base/macros.h"
|
|
|
|
namespace art {
|
|
|
|
// Hash bytes using a relatively fast hash.
|
|
static inline size_t HashBytes(const uint8_t* data, size_t len) {
|
|
size_t hash = 0x811c9dc5;
|
|
for (uint32_t i = 0; i < len; ++i) {
|
|
hash = (hash * 16777619) ^ data[i];
|
|
}
|
|
hash += hash << 13;
|
|
hash ^= hash >> 7;
|
|
hash += hash << 3;
|
|
hash ^= hash >> 17;
|
|
hash += hash << 5;
|
|
return hash;
|
|
}
|
|
|
|
class DataHash {
|
|
private:
|
|
static constexpr bool kUseMurmur3Hash = true;
|
|
|
|
public:
|
|
template <class Container>
|
|
size_t operator()(const Container& array) const {
|
|
// Containers that provide the data() function use contiguous storage.
|
|
const uint8_t* data = reinterpret_cast<const uint8_t*>(array.data());
|
|
uint32_t len = sizeof(typename Container::value_type) * array.size();
|
|
if (kUseMurmur3Hash) {
|
|
static constexpr uint32_t c1 = 0xcc9e2d51;
|
|
static constexpr uint32_t c2 = 0x1b873593;
|
|
static constexpr uint32_t r1 = 15;
|
|
static constexpr uint32_t r2 = 13;
|
|
static constexpr uint32_t m = 5;
|
|
static constexpr uint32_t n = 0xe6546b64;
|
|
|
|
uint32_t hash = 0;
|
|
|
|
const int nblocks = len / 4;
|
|
typedef __attribute__((__aligned__(1))) uint32_t unaligned_uint32_t;
|
|
const unaligned_uint32_t *blocks = reinterpret_cast<const uint32_t*>(data);
|
|
int i;
|
|
for (i = 0; i < nblocks; i++) {
|
|
uint32_t k = blocks[i];
|
|
k *= c1;
|
|
k = (k << r1) | (k >> (32 - r1));
|
|
k *= c2;
|
|
|
|
hash ^= k;
|
|
hash = ((hash << r2) | (hash >> (32 - r2))) * m + n;
|
|
}
|
|
|
|
const uint8_t *tail = reinterpret_cast<const uint8_t*>(data + nblocks * 4);
|
|
uint32_t k1 = 0;
|
|
|
|
switch (len & 3) {
|
|
case 3:
|
|
k1 ^= tail[2] << 16;
|
|
FALLTHROUGH_INTENDED;
|
|
case 2:
|
|
k1 ^= tail[1] << 8;
|
|
FALLTHROUGH_INTENDED;
|
|
case 1:
|
|
k1 ^= tail[0];
|
|
|
|
k1 *= c1;
|
|
k1 = (k1 << r1) | (k1 >> (32 - r1));
|
|
k1 *= c2;
|
|
hash ^= k1;
|
|
}
|
|
|
|
hash ^= len;
|
|
hash ^= (hash >> 16);
|
|
hash *= 0x85ebca6b;
|
|
hash ^= (hash >> 13);
|
|
hash *= 0xc2b2ae35;
|
|
hash ^= (hash >> 16);
|
|
|
|
return hash;
|
|
} else {
|
|
return HashBytes(data, len);
|
|
}
|
|
}
|
|
};
|
|
|
|
} // namespace art
|
|
|
|
#endif // ART_LIBARTBASE_BASE_DATA_HASH_H_
|