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#include "compat/defs.hpp"
#include "int-hash.hpp"
#include <bit>
namespace floormat {
namespace {
template<typename T> struct fnvhash_params;
template<> struct fnvhash_params<uint32_t> { uint32_t a = 0x811c9dc5u, b = 0x01000193u; };
template<> struct fnvhash_params<uint64_t> { uint64_t a = 0xcbf29ce484222325u, b = 0x100000001b3u; };
[[maybe_unused]]
CORRADE_ALWAYS_INLINE size_t fnvhash_uint_32(uint32_t x)
{
constexpr auto params = fnvhash_params<std::common_type_t<size_t>>{};
constexpr auto a = params.a, b = params.b;
auto hash = a;
const auto* str = (const char*)&x;
hash *= b; hash ^= (uint8_t)*str++; // 0
hash *= b; hash ^= (uint8_t)*str++; // 1
hash *= b; hash ^= (uint8_t)*str++; // 2
hash *= b; hash ^= (uint8_t)*str++; // 3
return hash;
}
CORRADE_ALWAYS_INLINE size_t fnvhash_uint_64(uint64_t x)
{
constexpr auto params = fnvhash_params<std::common_type_t<size_t>>{};
constexpr auto a = params.a, b = params.b;
auto hash = a;
const auto* str = (const char*)&x;
hash *= b; hash ^= (uint8_t)*str++; // 0
hash *= b; hash ^= (uint8_t)*str++; // 1
hash *= b; hash ^= (uint8_t)*str++; // 2
hash *= b; hash ^= (uint8_t)*str++; // 3
hash *= b; hash ^= (uint8_t)*str++; // 4
hash *= b; hash ^= (uint8_t)*str++; // 5
hash *= b; hash ^= (uint8_t)*str++; // 6
hash *= b; hash ^= (uint8_t)*str++; // 7
return hash;
}
} // namespace
uint32_t hash_32(const void* buf, size_t size) noexcept
{
constexpr auto params = fnvhash_params<std::common_type_t<uint32_t>>{};
constexpr auto a = params.a, b = params.b;
auto hash = a;
const auto *str = (const char*)buf, *const end = str + size;
fm_UNROLL_4
for (; str != end; ++str)
{
hash *= b;
hash ^= (uint8_t)*str;
}
return hash;
}
uint64_t hash_64(const void* buf, size_t size) noexcept
{
constexpr auto params = fnvhash_params<std::common_type_t<size_t>>{};
constexpr auto a = params.a, b = params.b;
auto hash = a;
const auto *str = (const char*)buf, *const end = str + size;
fm_UNROLL_8
for (; str != end; ++str)
{
hash *= b;
hash ^= (uint8_t)*str;
}
return hash;
}
size_t hash_int(uint32_t x) noexcept
{
return fnvhash_uint_32(x);
}
size_t hash_int(uint64_t x) noexcept
{
return fnvhash_uint_64(x);
}
} // namespace floormat
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