*-----------------------------------------------------------
* Title      : 
* Written by : Luigi Coppolino
* Date       :
* Description: each click to the button for IRQ1 makes the light go
*              around the led bank 1 step per click; IRQ2 ... 2 steps 
*              per click. 
*-----------------------------------------------------------
    ORG    $1000
START:                  ; first instruction of program

* Put program code here
;prepare IRQ vector for autovector 1
    move.l  #irq1,$64
    move.l  #irq2,$68
    
    MOVE.B 	#2, D1
    MOVE.B  #32, D0
    TRAP    #15
    MOVEA.L  D1,A0

    CLR     D2
    MOVE.B  #$80,(A0)    ; switch off all the leds but one
   
    andi.w   #$00,SR        ;put CPU in User mode       
 
LOOP 
    nop
    nop
    BRA     LOOP    
    
LED_SWITCH

irq1 
    MOVE.L  D2,-(SP)
    MOVE.L  D1,-(SP)
    MOVE.L  D0,-(SP)
    MOVE.B 	#2, D1
    MOVE.B  #32, D0
    TRAP    #15
    
    MOVEA.L  D1,A0
    MOVE.B  (A0),D2      ; D2 is the status of LEDs
    ROR.B   #1,D2
    MOVE.B  D2,(A0)
    
    MOVE.L  (SP)+,D0
    MOVE.L  (SP)+,D1
    MOVE.L  (SP)+,D2
    
    rte 
 

irq2
    MOVE.L  D2,-(SP)
    MOVE.L  D1,-(SP)
    MOVE.L  D0,-(SP)
    MOVE.B 	#2, D1
    MOVE.B  #32, D0
    TRAP    #15
    
    MOVE.B  (A0),D2      ; D2 is the status of LEDs
    ROR.B   #2,D2
    MOVE.B  D2,(A0)
    
    MOVE.L  (SP)+,D0
    MOVE.L  (SP)+,D1
    MOVE.L  (SP)+,D2

    rte 
    
    END    START        ; last line of source








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