/src/flatbuffers/include/flatbuffers/hash.h

Source
/*
 * 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_

Coverage Report

Created: 2026-02-26 06:24

Line	Count	Source
1		/*
2		* Copyright 2015 Google Inc. All rights reserved.
3		*
4		* Licensed under the Apache License, Version 2.0 (the "License");
5		* you may not use this file except in compliance with the License.
6		* You may obtain a copy of the License at
7		*
8		* http://www.apache.org/licenses/LICENSE-2.0
9		*
10		* Unless required by applicable law or agreed to in writing, software
11		* distributed under the License is distributed on an "AS IS" BASIS,
12		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13		* See the License for the specific language governing permissions and
14		* limitations under the License.
15		*/
16
17		#ifndef FLATBUFFERS_HASH_H_
18		#define FLATBUFFERS_HASH_H_
19
20		#include <cstdint>
21		#include <cstring>
22
23		#include "flatbuffers/flatbuffers.h"
24
25		namespace flatbuffers {
26
27		template <typename T>
28		struct FnvTraits {
29		static const T kFnvPrime;
30		static const T kOffsetBasis;
31		};
32
33		template <>
34		struct FnvTraits<uint32_t> {
35		static const uint32_t kFnvPrime = 0x01000193;
36		static const uint32_t kOffsetBasis = 0x811C9DC5;
37		};
38
39		template <>
40		struct FnvTraits<uint64_t> {
41		static const uint64_t kFnvPrime = 0x00000100000001b3ULL;
42		static const uint64_t kOffsetBasis = 0xcbf29ce484222645ULL;
43		};
44
45		template <typename T>
46	0	T HashFnv1(const char* input) {
47	0	T hash = FnvTraits<T>::kOffsetBasis;
48	0	for (const char* c = input; *c; ++c) {
49	0	hash *= FnvTraits<T>::kFnvPrime;
50	0	hash ^= static_cast<unsigned char>(*c);
51	0	}
52	0	return hash;
53	0	} Unexecuted instantiation: unsigned int flatbuffers::HashFnv1<unsigned int>(char const) Unexecuted instantiation: unsigned long flatbuffers::HashFnv1<unsigned long>(char const)
54
55		template <typename T>
56	0	T HashFnv1a(const char* input) {
57	0	T hash = FnvTraits<T>::kOffsetBasis;
58	0	for (const char* c = input; *c; ++c) {
59	0	hash ^= static_cast<unsigned char>(*c);
60	0	hash *= FnvTraits<T>::kFnvPrime;
61	0	}
62	0	return hash;
63	0	} Unexecuted instantiation: unsigned int flatbuffers::HashFnv1a<unsigned int>(char const) Unexecuted instantiation: unsigned long flatbuffers::HashFnv1a<unsigned long>(char const)
64
65		template <>
66	0	inline uint16_t HashFnv1<uint16_t>(const char* input) {
67	0	uint32_t hash = HashFnv1<uint32_t>(input);
68	0	return (hash >> 16) ^ (hash & 0xffff);
69	0	}
70
71		template <>
72	0	inline uint16_t HashFnv1a<uint16_t>(const char* input) {
73	0	uint32_t hash = HashFnv1a<uint32_t>(input);
74	0	return (hash >> 16) ^ (hash & 0xffff);
75	0	}
76
77		template <typename T>
78		struct NamedHashFunction {
79		const char* name;
80
81		typedef T (HashFunction)(const char);
82		HashFunction function;
83		};
84
85		const NamedHashFunction<uint16_t> kHashFunctions16[] = {
86		{"fnv1_16", HashFnv1<uint16_t>},
87		{"fnv1a_16", HashFnv1a<uint16_t>},
88		};
89
90		const NamedHashFunction<uint32_t> kHashFunctions32[] = {
91		{"fnv1_32", HashFnv1<uint32_t>},
92		{"fnv1a_32", HashFnv1a<uint32_t>},
93		};
94
95		const NamedHashFunction<uint64_t> kHashFunctions64[] = {
96		{"fnv1_64", HashFnv1<uint64_t>},
97		{"fnv1a_64", HashFnv1a<uint64_t>},
98		};
99
100		inline NamedHashFunction<uint16_t>::HashFunction FindHashFunction16(
101	0	const char* name) {
102	0	std::size_t size = sizeof(kHashFunctions16) / sizeof(kHashFunctions16[0]);
103	0	for (std::size_t i = 0; i < size; ++i) {
104	0	if (std::strcmp(name, kHashFunctions16[i].name) == 0) {
105	0	return kHashFunctions16[i].function;
106	0	}
107	0	}
108	0	return nullptr;
109	0	}
110
111		inline NamedHashFunction<uint32_t>::HashFunction FindHashFunction32(
112	0	const char* name) {
113	0	std::size_t size = sizeof(kHashFunctions32) / sizeof(kHashFunctions32[0]);
114	0	for (std::size_t i = 0; i < size; ++i) {
115	0	if (std::strcmp(name, kHashFunctions32[i].name) == 0) {
116	0	return kHashFunctions32[i].function;
117	0	}
118	0	}
119	0	return nullptr;
120	0	}
121
122		inline NamedHashFunction<uint64_t>::HashFunction FindHashFunction64(
123	0	const char* name) {
124	0	std::size_t size = sizeof(kHashFunctions64) / sizeof(kHashFunctions64[0]);
125	0	for (std::size_t i = 0; i < size; ++i) {
126	0	if (std::strcmp(name, kHashFunctions64[i].name) == 0) {
127	0	return kHashFunctions64[i].function;
128	0	}
129	0	}
130	0	return nullptr;
131	0	}
132
133		} // namespace flatbuffers
134
135		#endif // FLATBUFFERS_HASH_H_