1 files changed, 69 insertions, 0 deletions
diff --git a/src/database/database.cpp b/src/database/database.cpp
new file mode 100644
index 000000000..12e0e1a0f
--- /dev/null
+++ b/src/database/database.cpp
@@ -0,0 +1,69 @@
+/*
+Minetest
+Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program 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 Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "database.h"
+#include "irrlichttypes.h"
+
+
+/****************
+ * Black magic! *
+ ****************
+ * The position hashing is very messed up.
+ * It's a lot more complicated than it looks.
+ */
+
+static inline s16 unsigned_to_signed(u16 i, u16 max_positive)
+{
+	if (i < max_positive) {
+		return i;
+	}
+
+	return i - (max_positive * 2);
+}
+
+
+// Modulo of a negative number does not work consistently in C
+static inline s64 pythonmodulo(s64 i, s16 mod)
+{
+	if (i >= 0) {
+		return i % mod;
+	}
+	return mod - ((-i) % mod);
+}
+
+
+s64 MapDatabase::getBlockAsInteger(const v3s16 &pos)
+{
+	return (u64) pos.Z * 0x1000000 +
+		(u64) pos.Y * 0x1000 +
+		(u64) pos.X;
+}
+
+
+v3s16 MapDatabase::getIntegerAsBlock(s64 i)
+{
+	v3s16 pos;
+	pos.X = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
+	i = (i - pos.X) / 4096;
+	pos.Y = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
+	i = (i - pos.Y) / 4096;
+	pos.Z = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
+	return pos;
+}
+