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#pragma once
#include "asl/integers.hpp"
namespace asl::city_hash
{
// All CityHash stuff below this point
// Hash function for a byte array.
uint64_t CityHash64(const char *s, size_t len);
// Hash function for a byte array. For convenience, a 64-bit seed is also
// hashed into the result.
uint64_t CityHash64WithSeed(const char *s, size_t len, uint64_t seed);
// Hash function for a byte array. For convenience, two seeds are also
// hashed into the result.
uint64_t CityHash64WithSeeds(const char *s, size_t len,
uint64_t seed0, uint64_t seed1);
// Hash function for a byte array.
uint128_t CityHash128(const char *s, size_t len);
// Hash function for a byte array. For convenience, a 128-bit seed is also
// hashed into the result.
uint128_t CityHash128WithSeed(const char *s, size_t len, uint128_t seed);
// Hash function for a byte array. Most useful in 32-bit binaries.
uint32_t CityHash32(const char *s, size_t len);
// Hash 128 input bits down to 64 bits of output.
// This is intended to be a reasonably good hash function.
constexpr uint64_t Hash128to64(uint64_t high, uint64_t low)
{
// Murmur-inspired hashing.
const uint64_t kMul = 0x9ddfea08eb382d69ULL;
uint64_t a = (low ^ high) * kMul;
a ^= (a >> 47);
uint64_t b = (high ^ a) * kMul;
b ^= (b >> 47);
b *= kMul;
return b;
}
// Hash 128 input bits down to 64 bits of output.
// This is intended to be a reasonably good hash function.
constexpr uint64_t Hash128to64(const uint128_t& x)
{
return Hash128to64(x.high, x.low);
}
} // namespace asl::city_hash
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