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85 lines
1.7 KiB
C
85 lines
1.7 KiB
C
#pragma once
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//
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// FILE: randomHelpers.h
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// AUTHOR: Rob Tillaart
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// VERSION: 0.2.5
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// PURPOSE: Arduino library with helper function for faster random bits
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// URL: https://github.com/RobTillaart/randomHelpers
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#include "Arduino.h"
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#define RANDOM_HELPERS_VERSION (F("0.2.5"))
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// the idea is to have one buffer ( __randomBuffer) which holds 32 random bits.
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// Every call fetches bits from that buffer and if it does not hold enough
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// bits any more it fills the buffer first. This way the relative expensive
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// calls to random() which produces a 32 bit number are minimized in an
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// efficient way.
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//
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// TBD: put it in a class ?
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///////////////////////////////////////////////////////////////////////////
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//
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// An example of a simple pseudo-random number generator is the
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// Multiply-with-carry method invented by George Marsaglia.
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// it has two initializers (not zero) which can be changed
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// to seed the generator.
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//
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uint32_t Marsaglia();
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bool seedMarsaglia(uint32_t a, uint32_t b);
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uint32_t getRandom32();
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bool getRandom1();
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// typical use
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bool inline flipCoin();
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uint8_t getRandom4();
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uint8_t getRandom5();
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uint8_t getRandom6();
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// typical use
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uint8_t throwDice();
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uint8_t getRandom8();
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uint16_t getRandom16();
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uint32_t getRandom24();
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uint64_t getRandom64();
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/*
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// works well for 1..16; but above it is worse
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uint32_t getRandomBits(uint8_t n)
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{
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if (__randomIdx < n)
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{
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__randomBuffer = getRandom32();
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__randomIdx = 32;
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}
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uint32_t rv = __randomBuffer & ((1UL << n) - 1);
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__randomBuffer >>= n;
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__randomIdx -= n;
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return rv;
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}
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*/
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// n = 1..31
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// TODO: performance gain too low for n > 16
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uint32_t getRandomBits(uint8_t n);
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// -- END OF FILE --
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