mirror of
https://github.com/moparisthebest/minetest
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41bc24477b
This reverts commitsa2003b0d55and54ffe2e5de. These weren't correct. Add a black magic warning instead.
70 lines
1.7 KiB
C++
70 lines
1.7 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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#include "database.h"
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#include "irrlichttypes.h"
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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 s16 unsigned_to_signed(u16 i, u16 max_positive)
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{
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if (i < max_positive) {
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return i;
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} else {
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return 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 s64 pythonmodulo(s64 i, s16 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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s64 Database::getBlockAsInteger(const v3s16 pos) const
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{
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return (u64) pos.Z * 0x1000000 +
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(u64) pos.Y * 0x1000 +
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(u64) pos.X;
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}
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v3s16 Database::getIntegerAsBlock(s64 i) const
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{
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v3s16 pos;
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pos.X = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
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i = (i - pos.X) / 4096;
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pos.Y = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
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i = (i - pos.Y) / 4096;
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pos.Z = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
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return pos;
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}
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