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#pragma once
#include <cstdint>
#include <cstring>
#include <type_traits>
namespace Slang
{
//
// Types
//
struct StableHashCode64
{
uint64_t hash;
explicit operator uint64_t() const { return hash; }
bool operator==(StableHashCode64 other) const { return other.hash == hash; };
bool operator!=(StableHashCode64 other) const { return other.hash != hash; };
};
struct StableHashCode32
{
uint32_t hash;
explicit operator uint32_t() const { return hash; }
bool operator==(StableHashCode32 other) const { return other.hash == hash; };
bool operator!=(StableHashCode32 other) const { return other.hash != hash; };
};
/* The 'Stable' hash code functions produce hashes that must be
* The same result for the same inputs on all targets
* Rarely change - as their values can change the output of the Slang API/Serialization
Hash value used from the 'Stable' functions can also be used as part of serialization -
so it is in effect part of the API.
In effect this means changing a 'Stable' algorithm will typically require doing a new release.
*/
inline StableHashCode64 getStableHashCode64(const char* buffer, size_t numChars)
{
uint64_t hash = 0;
for (size_t i = 0; i < numChars; ++i)
{
hash = uint64_t(buffer[i]) + (hash << 6) + (hash << 16) - hash;
}
return StableHashCode64{hash};
}
template<typename T>
inline StableHashCode64 getStableHashCode64(const T& t)
{
static_assert(std::has_unique_object_representations_v<T>);
return getStableHashCode64(reinterpret_cast<const char*>(&t), sizeof(T));
}
inline StableHashCode32 getStableHashCode32(const char* buffer, size_t numChars)
{
uint32_t hash = 0;
for (size_t i = 0; i < numChars; ++i)
{
hash = uint32_t(buffer[i]) + (hash << 6) + (hash << 16) - hash;
}
return StableHashCode32{hash};
}
template<typename T>
inline StableHashCode32 getStableHashCode32(const T& t)
{
static_assert(std::has_unique_object_representations_v<T>);
return getStableHashCode32(reinterpret_cast<const char*>(&t), sizeof(T));
}
inline StableHashCode64 combineStableHash(StableHashCode64 h)
{
return h;
}
inline StableHashCode32 combineStableHash(StableHashCode32 h)
{
return h;
}
// A left fold with a mixing operation
template<typename H, typename... Hs>
H combineStableHash(H n, H m, Hs... args)
{
return combineStableHash(H{(n.hash * 16777619) ^ m.hash}, args...);
}
}
// > Please draw a small horse in ASCII art:
//
// ,~~.
// ( 9 )-_,
// (\___ )=='-' )
// \ . ) ) /
// \ `-' / /
// ~'`~'`~'`~'`~
//
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