Add a simple 32 bit to 32 bit hash function (MurmurHash3)

src/core/CMakeLists.txt

@@ -11,6 +11,7 @@ add_files(
     endian_func.hpp
     endian_type.hpp
     enum_type.hpp
+    hash_func.hpp
     geometry_func.cpp
     geometry_func.hpp
     geometry_type.hpp

src/core/hash_func.hpp

@@ -0,0 +1,28 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file hash_func.hpp Functions related to hashing operations. */
+
+#ifndef HASH_FUNC_HPP
+#define HASH_FUNC_HPP
+
+/**
+ * Simple 32 bit to 32 bit hash
+ * From MurmurHash3
+ */
+inline uint32 SimpleHash32(uint32 h)
+{
+	h ^= h >> 16;
+	h *= 0x85ebca6b;
+	h ^= h >> 13;
+	h *= 0xc2b2ae35;
+	h ^= h >> 16;
+
+	return h;
+}
+
+#endif /* HASH_FUNC_HPP */