Added the cFastRandom class

git-svn-id: http://mc-server.googlecode.com/svn/trunk@1672 0a769ca7-a7f5-676a-18bf-c427514a06d6
2013-07-11 08:34:41 +00:00
parent 94a92a219b
commit f5e475d44f
3 changed files with 239 additions and 0 deletions
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+
+// FastRandom.h
+
+// Declares the cFastRandom class representing a fast random number generator
+
+/*
+The cFastRandom aims to provide a very fast, although not very cryptographically secure, random generator.
+It is fast to instantiate, fast to query next, and partially multi-thread-safe.
+It is multi-thread-safe in the sense that it can be accessed from multiple threads without crashing, but it may
+yield duplicate numbers in that case.
+
+Internally, this works similar to cNoise's integral noise generation, with some predefined inputs: the seed is
+taken from a global counter and the random is calculated using a counter that is incremented on each use (hence
+the multi-thread duplication). Two alternatives exists for each function, one that takes a range parameter,
+and another that takes an additional "salt" parameter; this salt is used as an additional input to the random,
+in order to avoid multi-thread duplication. If two threads both use the class at the same time with different
+salts, the values they get will be different.
+*/
+
+
+
+
+
+#pragma once
+
+
+
+
+
+class cFastRandom
+{
+public:
+	cFastRandom(void);
+	
+	/// Returns a random int in the range [0 .. a_Range - 1]; a_Range must be less than 1M
+	int NextInt(int a_Range);
+
+	/// Returns a random int in the range [0 .. a_Range - 1]; a_Range must be less than 1M; a_Salt is additional source of randomness
+	int NextInt(int a_Range, int a_Salt);
+	
+	/// Returns a random float in the range [0 .. a_Range]; a_Range must be less than 1M
+	float NextFloat(float a_Range);
+
+	/// Returns a random float in the range [0 .. a_Range]; a_Range must be less than 1M; a_Salt is additional source of randomness
+	float NextFloat(float a_Range, int a_Salt);
+	
+protected:
+	int m_Seed;
+	int m_Counter;
+	
+	/// Counter that is used to initialize the seed, incremented for each object created
+	static int m_SeedCounter;
+} ;
+
+
+
+