module comblckf 
title 'Combination-Lock State Machine' 
"COMBLCKF device ’P16V8R’;

" Input and output pins 
CLOCK, RESET, X              pin 1, 2, 3; 
X1..X7                       pin 12..18 istype 'reg'; 
UNLK                         pin 19;

" Sets 
XHISTORY = [X7..X1]; 
SHIFTX  =  [X6..X1, X];

equations

XHISTORY.CLK = CLOCK;
XHISTORY := !RESET & SHIFTX;

UNLK = !RESET & (X == 0) & (XHISTORY == [0,1,1,0,1,1,1]);

END comblckf