15 lines
649 B
C++
15 lines
649 B
C++
#pragma once
|
|
#include <stdint.h>
|
|
|
|
// FNV1a c++11 constexpr compile time hash functions, 32 and 64 bit
|
|
// str should be a null terminated string literal, value should be left out
|
|
// e.g hash_32_fnv1a_const("example")
|
|
// code license: public domain or equivalent
|
|
// post: https://notes.underscorediscovery.com/constexpr-fnv1a/
|
|
|
|
constexpr uint32_t val_32_const = 0x811c9dc5;
|
|
constexpr uint32_t prime_32_const = 0x1000193;
|
|
|
|
inline constexpr uint32_t hash_32_fnv1a_const(const char* const str, const uint32_t value = val_32_const) noexcept {
|
|
return (str[0] == '\0') ? value : hash_32_fnv1a_const(&str[1], (value ^ uint32_t(str[0])) * prime_32_const);
|
|
} |