#include "lcg.h"
/* Dead simple 8-bit Linear Congruential Generator (PRNG).
*
* An LCG is defined as
*
* X(n+1) = ( a * X(n) + c ) % m
*
* In this implementation:
* a = 2^7 = 128
* c = 251
* m = 256
*
* Like all LCGs, the low-order bits of this cycle quickly. The
* high-order bits have better (longer) periods.
*/
LCG::LCG(uint16_t s)
{
seed = s;
}
void LCG::srnd(uint16_t s)
{
seed = s;
}
uint8_t LCG::rnd()
{
seed = (seed << 7) - seed + 251;
return (uint8_t)(seed + (seed>>8));
}