src/core/random_func.cpp

   1 /* $Id$ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * 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.
   6  * 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.
   7  * 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/>.
   8  */
   9
  10 /** @file random_func.cpp Implementation of the pseudo random generator. */
  11
  12 #include "../stdafx.h"
  13 #include "random_func.hpp"
  14 #include "bitmath_func.hpp"
  15
  16 Randomizer _random, _interactive_random;
  17
  18 /**
  19  * Generate the next pseudo random number
  20  * @return the random number
  21  */
  22 uint32 Randomizer::Next()
  23 {
  24         const uint32 s = this->state[0];
  25         const uint32 t = this->state[1];
  26
  27         this->state[0] = s + ROR(t ^ 0x1234567F, 7) + 1;
  28         return this->state[1] = ROR(s, 3) - 1;
  29 }
  30
  31 /**
  32  * Generate the next pseudo random number scaled to \a limit, excluding \a limit
  33  * itself.
  34  * @param limit Limit of the range to be generated from.
  35  * @return Random number in [0,\a limit)
  36  */
  37 uint32 Randomizer::Next(uint32 limit)
  38 {
  39         return ((uint64)this->Next() * (uint64)limit) >> 32;
  40 }
  41
  42 /**
  43  * (Re)set the state of the random number generator.
  44  * @param seed the new state
  45  */
  46 void Randomizer::SetSeed(uint32 seed)
  47 {
  48         this->state[0] = seed;
  49         this->state[1] = seed;
  50 }
  51
  52 /**
  53  * (Re)set the state of the random number generators.
  54  * @param seed the new state
  55  */
  56 void SetRandomSeed(uint32 seed)
  57 {
  58         _random.SetSeed(seed);
  59         _interactive_random.SetSeed(seed * 0x1234567);
  60 }
  61
  62 #ifdef RANDOM_DEBUG
  63 #include "../network/network.h"
  64 #include "../network/network_server.h"
  65 #include "../network/network_internal.h"
  66 #include "../company_func.h"
  67 #include "../fileio_func.h"
  68 #include "../date_func.h"
  69
  70 uint32 DoRandom(int line, const char *file)
  71 {
  72         if (_networking && (!_network_server || (NetworkClientSocket::IsValidID(0) && NetworkClientSocket::Get(0)->status != NetworkClientSocket::STATUS_INACTIVE))) {
  73                 DEBUG(random, 0, "%08x; %02x; %04x; %02x; %s:%d", _date, _date_fract, _frame_counter, (byte)_current_company, file, line);
  74         }
  75
  76         return _random.Next();
  77 }
  78
  79 uint32 DoRandomRange(uint32 limit, int line, const char *file)
  80 {
  81         return ((uint64)DoRandom(line, file) * (uint64)limit) >> 32;
  82 }
  83 #endif /* RANDOM_DEBUG */