xor-prng

variable rng-seed
62946839 rng-seed ! ( Default seed value )

( 32-bit version )
: rng ( -- n )
	rng-seed @
	dup 13 lshift xor ( For 16-bit systems 7 )
	dup 17 rshift xor ( For 16-bit systems 9 )
	dup 5  lshift xor ( For 16-bit systems 8 )
	dup rng-seed !
;
: choose ( upper-bound -- n ) rng abs swap mod ;
: coin ( -- n ) 2 choose ;