Line data    Source code

       1             : /*
       2             : Minetest
       3             : Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
       4             : 
       5             : This program is free software; you can redistribute it and/or modify
       6             : it under the terms of the GNU Lesser General Public License as published by
       7             : the Free Software Foundation; either version 2.1 of the License, or
       8             : (at your option) any later version.
       9             : 
      10             : This program is distributed in the hope that it will be useful,
      11             : but WITHOUT ANY WARRANTY; without even the implied warranty of
      12             : MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      13             : GNU Lesser General Public License for more details.
      14             : 
      15             : You should have received a copy of the GNU Lesser General Public License along
      16             : with this program; if not, write to the Free Software Foundation, Inc.,
      17             : 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
      18             : */
      19             : 
      20             : #include "database.h"
      21             : #include "irrlichttypes.h"
      22             : 
      23             : 
      24             : /****************
      25             :  * Black magic! *
      26             :  ****************
      27             :  * The position hashing is very messed up.
      28             :  * It's a lot more complicated than it looks.
      29             :  */
      30             : 
      31           0 : static inline s16 unsigned_to_signed(u16 i, u16 max_positive)
      32             : {
      33           0 :         if (i < max_positive) {
      34           0 :                 return i;
      35             :         } else {
      36           0 :                 return i - (max_positive * 2);
      37             :         }
      38             : }
      39             : 
      40             : 
      41             : // Modulo of a negative number does not work consistently in C
      42           0 : static inline s64 pythonmodulo(s64 i, s16 mod)
      43             : {
      44           0 :         if (i >= 0) {
      45           0 :                 return i % mod;
      46             :         }
      47           0 :         return mod - ((-i) % mod);
      48             : }
      49             : 
      50             : 
      51           0 : s64 Database::getBlockAsInteger(const v3s16 &pos)
      52             : {
      53           0 :         return (u64) pos.Z * 0x1000000 +
      54           0 :                 (u64) pos.Y * 0x1000 +
      55           0 :                 (u64) pos.X;
      56             : }
      57             : 
      58             : 
      59           0 : v3s16 Database::getIntegerAsBlock(s64 i)
      60             : {
      61           0 :         v3s16 pos;
      62           0 :         pos.X = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
      63           0 :         i = (i - pos.X) / 4096;
      64           0 :         pos.Y = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
      65           0 :         i = (i - pos.Y) / 4096;
      66           0 :         pos.Z = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
      67           0 :         return pos;
      68             : }
      69             :