Hash.hpp

#pragma once
 
#include "IntTypes.hpp"
 
namespace Grindstone {
    using HashValue = Uint64;
 
    namespace Hash {
        constexpr HashValue MurmurOAAT64(const char* key) {
            HashValue h(525201411107845655ull);
            for (; *key; ++key) {
                h ^= *key;
                h *= 0x5bd1e9955bd1e995;
                h ^= h >> 47;
            }
            return h;
        }
 
        constexpr HashValue MurmurOAAT64(const char* key, size_t length) {
            HashValue h(525201411107845655ull);
            for (size_t i = 0; i < length; ++i) {
                h ^= key[i];
                h *= 0x5bd1e9955bd1e995;
                h ^= h >> 47;
            }
            return h;
        }
 
        constexpr HashValue MurmurOAAT64(HashValue h, const char* key) {
            for (; *key; ++key) {
                h ^= *key;
                h *= 0x5bd1e9955bd1e995;
                h ^= h >> 47;
            }
            return h;
        }
 
        constexpr HashValue CombineMurmurOAAT64(HashValue h, const char* key, size_t length) {
            for (size_t i = 0; i < length; ++i) {
                h ^= key[i];
                h *= 0x5bd1e9955bd1e995;
                h ^= h >> 47;
            }
            return h;
        }
    };
 
}