70 lines
1.9 KiB
C
70 lines
1.9 KiB
C
/*
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Minetest
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Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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// This file was copied from the minetest code & minimally modified to suit
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// this codebase
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// Original filename: src/database.cpp
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//
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// For minetestmapper, this file should be included by BlockPos.h *only*
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/****************
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* Black magic! *
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****************
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* The position hashing is very messed up.
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* It's a lot more complicated than it looks.
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*/
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static inline int unsigned_to_signed(unsigned i, unsigned max_positive)
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{
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if (i < max_positive) {
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return static_cast<int>(i);
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} else {
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return static_cast<int>(i - (max_positive * 2));
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}
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}
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// Modulo of a negative number does not work consistently in C
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static inline unsigned pythonmodulo(int64_t i, unsigned mod)
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{
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if (i >= 0) {
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return i % mod;
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}
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return mod - ((-i) % mod);
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}
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inline int64_t getDBPos(void) const
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{
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return (uint64_t) z() * 0x1000000 +
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(uint64_t) y() * 0x1000 +
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(uint64_t) x();
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}
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inline void setFromDBPos(int64_t i)
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{
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x() = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
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i = (i - x()) / 4096;
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y() = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
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i = (i - y()) / 4096;
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z() = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
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}
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