;export symbols
	XDEF  RTI_ISR	
	XREF	__SEG_END_SSTACK,TON,TOFF,PRESSED,PORT_T,COUNTER
	
RTI_ISR:
            PSHA                    ;preserve registers
            PSHB
            PSHX
            PSHY
            
TheInterruptMain:
            LDAA  COUNTER           ;load the counter from the instructions into Acc. A
            INCA                    ;increment A
            STAA  COUNTER           ;now the counter has been incremented
            CMPA  TON               ;compare the (already incremented) counter to TON
            BLE   SetTAndReturn     ;branch if less than or equal to TON
                                    ;continue if the count is greater then TON
            CMPA  #15               ;check if the count (still in A) is less than or equal to 15
            BLE   ClearTAndReturn   ;branch if Acc. A (the count) is less than or equal to 15
                                    ;continue if the count is greater than 15
            BSET  COUNTER,#$00      ;clear the count
            BRA   Return            ;exit the interrupt routine
            
ClearTAndReturn:
            BCLR  PORT_T,#%00001000 ;clear bit 3 of Port T
            BRA   Return            ;exit the interrupt

SetTAndReturn:
            BSET  PORT_T,#%00001000 ;set bit 3 of Port T
            BRA   Return            ;exit the interrupt routine
            
Return:
            PULY                    ;restore the registers
            PULX
            PULB
            PULA
            
            RTI