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 #ifdef RANDOM_DEBUG
  17 #include "../network/network.h"
  18 #include "../network/network_server.h"
  19 #include "../network/network_internal.h"
  20 #include "../company_func.h"
  21 #include "../fileio_func.h"
  22 #include "../date_func.h"
  23 #endif /* RANDOM_DEBUG */
  24
  25 #include "../safeguards.h"
  26
  27 Randomizer _random, _interactive_random;
  28
  29 /**
  30  * Generate the next pseudo random number
  31  * @return the random number
  32  */
  33 uint32 Randomizer::Next()
  34 {
  35         const uint32 s = this->state[0];
  36         const uint32 t = this->state[1];
  37
  38         this->state[0] = s + ROR(t ^ 0x1234567F, 7) + 1;
  39         return this->state[1] = ROR(s, 3) - 1;
  40 }
  41
  42 /**
  43  * Generate the next pseudo random number scaled to \a limit, excluding \a limit
  44  * itself.
  45  * @param limit Limit of the range to be generated from.
  46  * @return Random number in [0,\a limit)
  47  */
  48 uint32 Randomizer::Next(uint32 limit)
  49 {
  50         return ((uint64)this->Next() * (uint64)limit) >> 32;
  51 }
  52
  53 /**
  54  * (Re)set the state of the random number generator.
  55  * @param seed the new state
  56  */
  57 void Randomizer::SetSeed(uint32 seed)
  58 {
  59         this->state[0] = seed;
  60         this->state[1] = seed;
  61 }
  62
  63 /**
  64  * (Re)set the state of the random number generators.
  65  * @param seed the new state
  66  */
  67 void SetRandomSeed(uint32 seed)
  68 {
  69         _random.SetSeed(seed);
  70         _interactive_random.SetSeed(seed * 0x1234567);
  71 }
  72
  73 #ifdef RANDOM_DEBUG
  74 uint32 DoRandom(int line, const char *file)
  75 {
  76         if (_networking && (!_network_server || (NetworkClientSocket::IsValidID(0) && NetworkClientSocket::Get(0)->status != NetworkClientSocket::STATUS_INACTIVE))) {
  77                 DEBUG(random, 0, "%08x; %02x; %04x; %02x; %s:%d", _date, _date_fract, _frame_counter, (byte)_current_company, file, line);
  78         }
  79
  80         return _random.Next();
  81 }
  82
  83 uint32 DoRandomRange(uint32 limit, int line, const char *file)
  84 {
  85         return ((uint64)DoRandom(line, file) * (uint64)limit) >> 32;
  86 }
  87 #endif /* RANDOM_DEBUG */