mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-10-03 18:09:02 -04:00
95 lines
1.8 KiB
C
95 lines
1.8 KiB
C
#pragma once
|
|
//
|
|
// FILE: randomHelpers.h
|
|
// AUTHOR: Rob Tillaart
|
|
// VERSION: 0.2.6
|
|
// PURPOSE: Arduino library with helper function for faster random bits
|
|
// URL: https://github.com/RobTillaart/randomHelpers
|
|
|
|
|
|
#include "Arduino.h"
|
|
|
|
#define RANDOM_HELPERS_VERSION (F("0.2.6"))
|
|
|
|
|
|
// the idea is to have one buffer ( __randomBuffer) which holds 32 random bits.
|
|
// Every call fetches bits from that buffer and if it does not hold enough
|
|
// bits any more it fills the buffer first. This way the relative expensive
|
|
// calls to random() which produces a 32 bit number are minimized in an
|
|
// efficient way.
|
|
//
|
|
// TBD: put it in a class ?
|
|
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
//
|
|
// An example of a simple pseudo-random number generator is the
|
|
// Multiply-with-carry method invented by George Marsaglia.
|
|
// it has two initializers (not zero) which can be changed
|
|
// to seed the generator.
|
|
//
|
|
|
|
uint32_t Marsaglia();
|
|
|
|
bool seedMarsaglia(uint32_t a, uint32_t b);
|
|
|
|
bool getRandom1();
|
|
|
|
uint8_t getRandom2();
|
|
|
|
uint8_t getRandom3();
|
|
|
|
uint8_t getRandom4();
|
|
|
|
uint8_t getRandom5();
|
|
|
|
uint8_t getRandom6();
|
|
|
|
uint8_t getRandom7();
|
|
|
|
uint8_t getRandom8();
|
|
|
|
uint16_t getRandom16();
|
|
|
|
uint32_t getRandom24();
|
|
|
|
uint32_t getRandom32();
|
|
|
|
uint64_t getRandom64();
|
|
|
|
|
|
/////////////////////////////////////////////////
|
|
//
|
|
// TYPICAL USES
|
|
//
|
|
bool inline flipCoin(); // 0..1
|
|
|
|
uint8_t throwDice(); // 1..6
|
|
|
|
|
|
|
|
/*
|
|
// works well for 1..16; but above it is worse
|
|
uint32_t getRandomBits(uint8_t n)
|
|
{
|
|
if (__randomIdx < n)
|
|
{
|
|
__randomBuffer = getRandom32();
|
|
__randomIdx = 32;
|
|
}
|
|
uint32_t rv = __randomBuffer & ((1UL << n) - 1);
|
|
__randomBuffer >>= n;
|
|
__randomIdx -= n;
|
|
return rv;
|
|
}
|
|
*/
|
|
|
|
|
|
// n = 1..31
|
|
// TODO: performance gain too low for n > 16
|
|
uint32_t getRandomBits(uint8_t n);
|
|
|
|
|
|
// -- END OF FILE --
|
|
|