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template specialized Hash functions for 16-bit hash types (#4631)

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added access to HashFunction for 16 bit
This commit is contained in:
Christian Helmich
2018-02-24 03:29:37 +09:00
committed by Wouter van Oortmerssen
parent b24c0b07a3
commit 6e2e909b5c
3 changed files with 62 additions and 6 deletions
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28
include/flatbuffers/hash.h
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@@ -57,13 +57,28 @@ template<typename T> T HashFnv1a(const char *input) {
return hash;
}
template<typename T> struct NamedHashFunction {
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> },
@@ -74,6 +89,17 @@ const NamedHashFunction<uint64_t> kHashFunctions64[] = {
{ "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]);