From f1d902ce9b08e166b33fe5f902a33cd950810d2f Mon Sep 17 00:00:00 2001
From: Merry <git@mary.rs>
Date: Sun, 1 May 2022 18:26:39 +0100
Subject: [PATCH] mcl: hash: Add xmrx

---
 include/mcl/hash/xmrx.hpp | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 include/mcl/hash/xmrx.hpp

diff --git a/include/mcl/hash/xmrx.hpp b/include/mcl/hash/xmrx.hpp
new file mode 100644
index 0000000..ebc0fb6
--- /dev/null
+++ b/include/mcl/hash/xmrx.hpp
@@ -0,0 +1,30 @@
+// This file is part of the mcl project.
+// Copyright (c) 2022 merryhime
+// SPDX-License-Identifier: MIT
+
+// Reference: http://jonkagstrom.com/bit-mixer-construction/
+
+#include <functional>
+
+#include "mcl/bit/rotate.hpp"
+#include "mcl/stdint.hpp"
+
+namespace mcl::hash {
+
+constexpr size_t xmrx(size_t x)
+{
+    x ^= x >> 32;
+    x *= 0xff51afd7ed558ccd;
+    x ^= bit::rotate_right(x, 47) ^ bit::rotate_right(x, 23);
+    return x;
+}
+
+template<typename T>
+struct avalanche_xmrx {
+    size_t operator()(const T& value)
+    {
+        return xmrx(std::hash<T>{}(value));
+    }
+};
+
+}  // namespace mcl::hash