Network: Add state checksum which is check in network sync

src/core/checksum_func.hpp

@@ -0,0 +1,33 @@
+/* $Id$ */
+
+/*
+ * 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 checksum_func.hpp Checksum utility functions. */
+
+#ifndef CHECKSUM_FUNC_HPP
+#define CHECKSUM_FUNC_HPP
+
+#include "bitmath_func.hpp"
+
+struct SimpleChecksum64 {
+	uint64 state = 0;
+
+	void Update(uint64 input)
+	{
+		this->state = ROL(this->state, 1) ^ input ^ 0x123456789ABCDEF7ULL;
+	}
+};
+
+extern SimpleChecksum64 _state_checksum;
+
+inline void UpdateStateChecksum(uint64 input)
+{
+	_state_checksum.Update(input);
+}
+
+#endif /* CHECKSUM_FUNC_HPP */

src/core/random_func.hpp

@@ -12,6 +12,8 @@
 #ifndef RANDOM_FUNC_HPP
 #define RANDOM_FUNC_HPP
 
+#include "bitmath_func.hpp"
+
 #if defined(__APPLE__)
 	/* Apple already has Random declared */
 	#define Random OTTD_Random