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#pragma once
#include <cstddef>
#include <bit>
namespace floormat {
constexpr inline std::size_t int_hash(std::size_t x) noexcept
{
if constexpr(sizeof(std::size_t) == 4)
{
// by Chris Wellons <https://nullprogram.com/blog/2018/07/31/>
x ^= x >> 15;
x *= 0x2c1b3c6dU;
x ^= x >> 12;
x *= 0x297a2d39U;
x ^= x >> 15;
}
else if constexpr(sizeof(std::size_t) == 8)
{
// NASAM by Pelle Evensen <https://mostlymangling.blogspot.com/2020/01/nasam-not-another-strange-acronym-mixer.html>
x ^= std::rotr(x, 25) ^ std::rotr(x, 47);
x *= 0x9E6C63D0676A9A99UL;
x ^= x >> 23 ^ x >> 51;
x *= 0x9E6D62D06F6A9A9BUL;
x ^= x >> 23 ^ x >> 51;
}
return x;
}
} // namespace floormat
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