rl      A		
        cjne    A,7,NOT7     ; A is never 7! Just affect C
NOT7:   jc      USE0_3	     ; use 0-3 when A < 7	
        add     A,#IM4_7+8   ; otherwise use 4-7	
        jmp     OVR0_3		
USE0_3: add     A,#IM0_3+8	
OVR0_3: mov     R0,A