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#INCLUDE	'a:\VAR_DEF.ASM'

* Define program variables
	ORG	DATA
T0	RMB	2	; time origin, t0
T1	RMB	2	; time t1
NOF1	RMB	1	; overflow counter 1



* Start main program
	ORG	PROGRAM
START	LDX	#REGBAS
	LDAA	#%00010000		; initialize TCTL2, EDG1A 
	STAA	TCTL2,X
	LDAA	#%00110000	; initialize BAUD=9600
	STAA	BAUD,X
	LDAA	#%00000000	; initialize 8-bit word
	STAA	SCCR1,X
	LDAA	#%00001100	; initialize TE and RE
	STAA	SCCR2,X

BEGIN	NOP
* Wait for a keypress reception
LABEL0	LDAA	SCSR,X	; check if RDRF is set
	ANDA	#%00100000	; mask for RDRF
	BEQ	LABEL0
* You are here after the key press
	LDAA	SCDR,X		; reset RDRF by reading SCDR
	LDD	TCNT,X		; store initial time
	STD	T0		; 
	LDAA	#$00		; zero overflow counter
	STAA	NOF1
	LDAA	#%10000000	; reset TOF
	STAA	TFLG2,X
* Wait for the input capture
LABEL1	LDAA	TFLG2,X		; check TOF
	ANDA	#%10000000	; TOF mask
	BEQ	LABEL2		; jump if no TOF
	INC	NOF1		; increment overflow counter
	LDAA	#%10000000	; reset TOF
	STAA	TFLG2,X	;
LABEL2	LDAA	TFLG1,X	; check IC1F
	ANDA	#%00000100	; AND with IC1F mask
	BEQ	LABEL1		; loop back
* We are here after input capture
	LDD	TIC1,X		; load and store t1
	STD	T1		;
	LDAA	#%00000100	; reset IC1F by writing 1 to it
	STAA	TFLG1,X
	BRA	BEGIN	; loop back to do it again

	SWI
	ORG	$FFFE	; reset vector
	FDB	START	; set to start of program