random_func.hpp

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00001 /* $Id: random_func.hpp 17248 2009-08-21 20:21:05Z rubidium $ */
00002 
00003 /*
00004  * This file is part of OpenTTD.
00005  * 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.
00006  * 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.
00007  * 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/>.
00008  */
00009 
00012 #ifndef RANDOM_FUNC_HPP
00013 #define RANDOM_FUNC_HPP
00014 
00015 #if defined(__APPLE__)
00016   /* Apple already has Random declared */
00017   #define Random OTTD_Random
00018 #endif /* __APPLE__ */
00019 
00020 /**************
00021  * Warning: DO NOT enable this unless you understand what it does
00022  *
00023  * If enabled, in a network game all randoms will be dumped to the
00024  *  stdout if the first client joins (or if you are a client). This
00025  *  is to help finding desync problems.
00026  *
00027  * Warning: DO NOT enable this unless you understand what it does
00028  **************/
00029 
00030 //#define RANDOM_DEBUG
00031 
00032 
00036 struct Randomizer {
00038   uint32 state[2];
00039 
00044   uint32 Next();
00045 
00051   uint32 Next(uint16 max);
00052 
00057   void SetSeed(uint32 seed);
00058 };
00059 extern Randomizer _random; 
00060 extern Randomizer _interactive_random; 
00061 
00063 struct SavedRandomSeeds {
00064   Randomizer random;
00065   Randomizer interactive_random;
00066 };
00067 
00071 static inline void SaveRandomSeeds(SavedRandomSeeds *storage)
00072 {
00073   storage->random = _random;
00074   storage->interactive_random = _interactive_random;
00075 }
00076 
00080 static inline void RestoreRandomSeeds(const SavedRandomSeeds &storage)
00081 {
00082   _random = storage.random;
00083   _interactive_random = storage.interactive_random;
00084 }
00085 
00086 void SetRandomSeed(uint32 seed);
00087 #ifdef RANDOM_DEBUG
00088   #define Random() DoRandom(__LINE__, __FILE__)
00089   uint32 DoRandom(int line, const char *file);
00090   #define RandomRange(max) DoRandomRange(max, __LINE__, __FILE__)
00091   uint DoRandomRange(uint max, int line, const char *file);
00092 #else
00093   static FORCEINLINE uint32 Random()
00094   {
00095     return _random.Next();
00096   }
00097 
00098   static FORCEINLINE uint32 RandomRange(uint16 max)
00099   {
00100     return _random.Next(max);
00101   }
00102 #endif
00103 
00104 static FORCEINLINE uint32 InteractiveRandom()
00105 {
00106   return _interactive_random.Next();
00107 }
00108 
00109 static FORCEINLINE uint32 InteractiveRandomRange(uint16 max)
00110 {
00111   return _interactive_random.Next(max);
00112 }
00113 
00129 static FORCEINLINE bool Chance16I(const uint a, const uint b, const uint32 r)
00130 {
00131   assert(b != 0);
00132   return (((uint16)r * b + b / 2) >> 16) < a;
00133 }
00134 
00145 #ifdef RANDOM_DEBUG
00146   #define Chance16(a, b) Chance16I(a, b, DoRandom(__LINE__, __FILE__))
00147 #else
00148 static FORCEINLINE bool Chance16(const uint a, const uint b)
00149 {
00150   return Chance16I(a, b, Random());
00151 }
00152 #endif /* RANDOM_DEBUG */
00153 
00169 #ifdef RANDOM_DEBUG
00170   #define Chance16R(a, b, r) (r = DoRandom(__LINE__, __FILE__), Chance16I(a, b, r))
00171 #else
00172 static FORCEINLINE bool Chance16R(const uint a, const uint b, uint32 &r)
00173 {
00174   r = Random();
00175   return Chance16I(a, b, r);
00176 }
00177 #endif /* RANDOM_DEBUG */
00178 
00179 #endif /* RANDOM_FUNC_HPP */

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