58 lines
1.8 KiB
C++
58 lines
1.8 KiB
C++
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// FastRandom.h
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// Declares the cFastRandom class representing a fast random number generator
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/*
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The cFastRandom aims to provide a very fast, although not very cryptographically secure, random generator.
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It is fast to instantiate, fast to query next, and partially multi-thread-safe.
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It is multi-thread-safe in the sense that it can be accessed from multiple threads without crashing, but it may
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yield duplicate numbers in that case.
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Internally, this works similar to cNoise's integral noise generation, with some predefined inputs: the seed is
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taken from a global counter and the random is calculated using a counter that is incremented on each use (hence
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the multi-thread duplication). Two alternatives exists for each function, one that takes a range parameter,
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and another that takes an additional "salt" parameter; this salt is used as an additional input to the random,
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in order to avoid multi-thread duplication. If two threads both use the class at the same time with different
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salts, the values they get will be different.
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*/
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#pragma once
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class cFastRandom
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{
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public:
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cFastRandom(void);
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/// Returns a random int in the range [0 .. a_Range - 1]; a_Range must be less than 1M
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int NextInt(int a_Range);
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/// 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
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int NextInt(int a_Range, int a_Salt);
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/// Returns a random float in the range [0 .. a_Range]; a_Range must be less than 1M
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float NextFloat(float a_Range);
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/// Returns a random float in the range [0 .. a_Range]; a_Range must be less than 1M; a_Salt is additional source of randomness
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float NextFloat(float a_Range, int a_Salt);
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protected:
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int m_Seed;
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int m_Counter;
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/// Counter that is used to initialize the seed, incremented for each object created
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static int m_SeedCounter;
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} ;
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