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-rw-r--r--compat/int-hash.cpp36
1 files changed, 16 insertions, 20 deletions
diff --git a/compat/int-hash.cpp b/compat/int-hash.cpp
index 00f2e474..72c38179 100644
--- a/compat/int-hash.cpp
+++ b/compat/int-hash.cpp
@@ -3,35 +3,31 @@
namespace floormat {
-size_t int_hash(uint32_t x) noexcept
+template<typename T, T offset_basis, T prime>
+static CORRADE_ALWAYS_INLINE
+T FNVHash(const char* str, size_t size)
{
- if constexpr(sizeof(size_t) == 4)
+ const auto* end = str + size;
+ T hash = offset_basis;
+ for (; str != end; ++str)
{
- // by Chris Wellons <https://nullprogram.com/blog/2018/07/31/>
-
- x ^= x >> 15;
- x *= 0x2c1b3c6dU;
- x ^= x >> 12;
- x *= 0x297a2d39U;
- x ^= x >> 15;
-
- return x;
+ hash *= prime;
+ hash ^= (uint8_t)*str;
}
+ return hash;
+}
+
+size_t int_hash(uint32_t x) noexcept
+{
+ if constexpr(sizeof(size_t) == 4)
+ return FNVHash<uint32_t, 0x811c9dc5u, 0x01000193u>((const char*)&x, 4);
else
return int_hash(uint64_t(x));
}
size_t int_hash(uint64_t x) noexcept
{
- // 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;
+ return FNVHash<uint64_t, 0xcbf29ce484222325u, 0x100000001b3u>((const char*)&x, 8);
}
} // namespace floormat