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Diffstat (limited to 'executor/_include/flatbuffers/hash.h')
| -rw-r--r-- | executor/_include/flatbuffers/hash.h | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/executor/_include/flatbuffers/hash.h b/executor/_include/flatbuffers/hash.h new file mode 100644 index 000000000..aebf0713f --- /dev/null +++ b/executor/_include/flatbuffers/hash.h @@ -0,0 +1,127 @@ +/* + * Copyright 2015 Google Inc. All rights reserved. + * + * 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 FLATBUFFERS_HASH_H_ +#define FLATBUFFERS_HASH_H_ + +#include <cstdint> +#include <cstring> + +#include "flatbuffers/flatbuffers.h" + +namespace flatbuffers { + +template<typename T> struct FnvTraits { + static const T kFnvPrime; + static const T kOffsetBasis; +}; + +template<> struct FnvTraits<uint32_t> { + static const uint32_t kFnvPrime = 0x01000193; + static const uint32_t kOffsetBasis = 0x811C9DC5; +}; + +template<> struct FnvTraits<uint64_t> { + static const uint64_t kFnvPrime = 0x00000100000001b3ULL; + static const uint64_t kOffsetBasis = 0xcbf29ce484222645ULL; +}; + +template<typename T> T HashFnv1(const char *input) { + T hash = FnvTraits<T>::kOffsetBasis; + for (const char *c = input; *c; ++c) { + hash *= FnvTraits<T>::kFnvPrime; + hash ^= static_cast<unsigned char>(*c); + } + return hash; +} + +template<typename T> T HashFnv1a(const char *input) { + T hash = FnvTraits<T>::kOffsetBasis; + for (const char *c = input; *c; ++c) { + hash ^= static_cast<unsigned char>(*c); + hash *= FnvTraits<T>::kFnvPrime; + } + return hash; +} + +template<> inline uint16_t HashFnv1<uint16_t>(const char *input) { + uint32_t hash = HashFnv1<uint32_t>(input); + return (hash >> 16) ^ (hash & 0xffff); +} + +template<> inline uint16_t HashFnv1a<uint16_t>(const char *input) { + uint32_t hash = HashFnv1a<uint32_t>(input); + return (hash >> 16) ^ (hash & 0xffff); +} + +template<typename T> struct NamedHashFunction { + const char *name; + + typedef T (*HashFunction)(const char *); + HashFunction function; +}; + +const NamedHashFunction<uint16_t> kHashFunctions16[] = { + { "fnv1_16", HashFnv1<uint16_t> }, + { "fnv1a_16", HashFnv1a<uint16_t> }, +}; + +const NamedHashFunction<uint32_t> kHashFunctions32[] = { + { "fnv1_32", HashFnv1<uint32_t> }, + { "fnv1a_32", HashFnv1a<uint32_t> }, +}; + +const NamedHashFunction<uint64_t> kHashFunctions64[] = { + { "fnv1_64", HashFnv1<uint64_t> }, + { "fnv1a_64", HashFnv1a<uint64_t> }, +}; + +inline NamedHashFunction<uint16_t>::HashFunction FindHashFunction16( + const char *name) { + std::size_t size = sizeof(kHashFunctions16) / sizeof(kHashFunctions16[0]); + for (std::size_t i = 0; i < size; ++i) { + if (std::strcmp(name, kHashFunctions16[i].name) == 0) { + return kHashFunctions16[i].function; + } + } + return nullptr; +} + +inline NamedHashFunction<uint32_t>::HashFunction FindHashFunction32( + const char *name) { + std::size_t size = sizeof(kHashFunctions32) / sizeof(kHashFunctions32[0]); + for (std::size_t i = 0; i < size; ++i) { + if (std::strcmp(name, kHashFunctions32[i].name) == 0) { + return kHashFunctions32[i].function; + } + } + return nullptr; +} + +inline NamedHashFunction<uint64_t>::HashFunction FindHashFunction64( + const char *name) { + std::size_t size = sizeof(kHashFunctions64) / sizeof(kHashFunctions64[0]); + for (std::size_t i = 0; i < size; ++i) { + if (std::strcmp(name, kHashFunctions64[i].name) == 0) { + return kHashFunctions64[i].function; + } + } + return nullptr; +} + +} // namespace flatbuffers + +#endif // FLATBUFFERS_HASH_H_ |
