; ** p7.stax ************************************************
; STAX program to accept the language { w | w = 0^(2^n), n>=0 }
; 
; John Haskins, Jr.
; l'Universite de Virginie (University of Virginia)
; jwh6q@virginia.edu
; -----------------------------------------------------------

	.input_alphabet		"0"
	.stack_alphabet		"a"

; initialize stacks...
qinit0:
	deny
	-, -, push[0]:$, q1
	$, -, nop, qdone
q1:
	deny
	'0', -, push[0]:'a', q1
	$, -, push[1]:$, q2

q2:
	deny
	-, 'a'[0], pop[0], q3
	-, $[0], nop, q5
q3:
	deny
	-, 'a'[0], pop[0], q4
	-, $[0], nop, q9
q4:
	deny
	-, -, push[1]:'a', q2

q5:
	deny
	-, 'a'[1], pop[1], q6
	-, $[1], nop, q2
q6:
	deny
	-, 'a'[1], pop[1], q7
	-, $[1], nop, q8
q7:
	deny
	-, -, push[0]:'a', q5

q8:
	deny
	-, $[0], nop, qdone
q9:
	deny
	-, $[1], nop, qdone

qdone:
	accept
	halt