# 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 */