random_func.hpp File Reference

Pseudo random number generator. More...

Go to the source code of this file.

Data Structures

struct  Randomizer
 Structure to encapsulate the pseudo random number generators. More...
struct  SavedRandomSeeds
 Stores the state of all random number generators. More...

Functions

static void SaveRandomSeeds (SavedRandomSeeds *storage)
 Saves the current seeds.
static void RestoreRandomSeeds (const SavedRandomSeeds &storage)
 Restores previously saved seeds.
void SetRandomSeed (uint32 seed)
 (Re)set the state of the random number generators.
static FORCEINLINE uint32 Random ()
static FORCEINLINE uint32 RandomRange (uint32 max)
static FORCEINLINE uint32 InteractiveRandom ()
static FORCEINLINE uint32 InteractiveRandomRange (uint32 max)
static FORCEINLINE bool Chance16I (const uint a, const uint b, const uint32 r)
 Checks if a given randomize-number is below a given probability.
static FORCEINLINE bool Chance16 (const uint a, const uint b)
 Flips a coin with given probability.
static FORCEINLINE bool Chance16R (const uint a, const uint b, uint32 &r)
 Flips a coin with a given probability and saves the randomize-number in a variable.

Variables

Randomizer _random
 Random used in the game state calculations.
Randomizer _interactive_random
 Random used every else where is does not (directly) influence the game state.

Detailed Description

Pseudo random number generator.

Definition in file random_func.hpp.


Function Documentation

static FORCEINLINE bool Chance16 ( const uint  a,
const uint  b 
) [static]

Flips a coin with given probability.

This function returns true with (a/b) probability.

See also:
Chance16I()
Parameters:
a The nominator of the fraction
b The denominator of the fraction
Returns:
True with (a/b) probability

Definition at line 139 of file random_func.hpp.

References Chance16I().

Referenced by BuildTownHouse(), ChangeIndustryProduction(), CreateNewLinks(), Disaster_Helicopter_Init(), DisasterTick_Submarine(), FindSupplySource(), GenerateTowns(), GrowTownInTile(), IndustryDailyLoop(), IsRoadAllowedHere(), Vehicle::ShowVisualEffect(), TileLoop_Town(), and UpdateTownGrowRate().

static FORCEINLINE bool Chance16I ( const uint  a,
const uint  b,
const uint32  r 
) [static]

Checks if a given randomize-number is below a given probability.

This function is used to check if the given probability by the fraction of (a/b) is greater than low 16 bits of the given randomize-number r.

Do not use this function twice on the same random 16 bits as it will yield the same result. One can use a random number for two calls to Chance16I, where one call sends the low 16 bits and the other the high 16 bits.

Parameters:
a The numerator of the fraction
b The denominator of the fraction, must of course not be null
r The given randomize-number
Returns:
True if the probability given by r is less or equal to (a/b)

Definition at line 120 of file random_func.hpp.

Referenced by Chance16(), Chance16R(), and ChangeIndustryProduction().

static FORCEINLINE bool Chance16R ( const uint  a,
const uint  b,
uint32 &  r 
) [static]

Flips a coin with a given probability and saves the randomize-number in a variable.

This function uses the same parameters as Chance16. The third parameter must be a variable the randomize-number from Random() is saved in.

The low 16 bits of r will already be used and can therefor not be passed to Chance16I. One can only send the high 16 bits to Chance16I.

See also:
Chance16I()
Parameters:
a The numerator of the fraction
b The denominator of the fraction
r The variable to save the randomize-number from Random()
Returns:
True in (a/b) percent

Definition at line 163 of file random_func.hpp.

References Chance16I().

Referenced by HandleCrashedAircraft(), and HandleCrashedTrain().

static void RestoreRandomSeeds ( const SavedRandomSeeds storage  )  [inline, static]

Restores previously saved seeds.

Parameters:
storage Storage where SaveRandomSeeds() stored th seeds

Definition at line 67 of file random_func.hpp.

Referenced by CmdAutoreplaceVehicle().

static void SaveRandomSeeds ( SavedRandomSeeds storage  )  [inline, static]

Saves the current seeds.

Parameters:
storage Storage for saving

Definition at line 57 of file random_func.hpp.

Referenced by CmdAutoreplaceVehicle().

void SetRandomSeed ( uint32  seed  ) 

(Re)set the state of the random number generators.

Parameters:
seed the new state

Definition at line 55 of file random_func.cpp.

References Randomizer::SetSeed().


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