module tbirdsdo
title 'Output-Coded T-Bird Tail Lights State Machine' 
"TBIRDSDO device 'P16V8R'; 

" Input and output pins 
CLOCK, LEFT, RIGHT, HAZ, RESET     pin 1, 2, 3, 4, 5;
L3Z, L2Z, L1Z, R1Z, R2Z, R3Z       pin 18..13 istype 'reg';

" Definitions 
QSTATE = [L3Z,L2Z,L1Z,R1Z,R2Z,R3Z];  " State variables 
IDLE   = [  0,  0,  0,  0,  0,  0];  " States 
L3     = [  1,  1,  1,  0,  0,  0]; 
L2     = [  0,  1,  1,  0,  0,  0]; 
L1     = [  0,  0,  1,  0,  0,  0]; 
R1     = [  0,  0,  0,  1,  0,  0]; 
R2     = [  0,  0,  0,  1,  1,  0]; 
R3     = [  0,  0,  0,  1,  1,  1]; 
LR3    = [  1,  1,  1,  1,  1,  1];

equations
QSTATE.CLK = CLOCK;

state_diagram QSTATE 
state IDLE: IF RESET THEN IDLE
            ELSE IF (HAZ # LEFT & RIGHT) THEN LR3
            ELSE IF LEFT THEN L1 ELSE IF RIGHT THEN R1
            ELSE IDLE; 
state L1:   IF RESET THEN IDLE ELSE IF HAZ THEN LR3 ELSE L2; 
state L2:   IF RESET THEN IDLE ELSE IF HAZ THEN LR3 ELSE L3; 
state L3:   GOTO IDLE; 
state R1:   IF RESET THEN IDLE ELSE IF HAZ THEN LR3 ELSE R2; 
state R2:   IF RESET THEN IDLE ELSE IF HAZ THEN LR3 ELSE R3; 
state R3:   GOTO IDLE; 
state LR3:  GOTO IDLE;

end tbirdsdo