//
//	serial.asm
//
//	reads serial line and echoes characters
//	writes reverse string after reading a CR
//
//	Testprogram for JOP
//
//	Copyrigth: Martin Schoeberl (martin.schoeberl@chello.at)
//

iobase	=	2097152
serial	=	2097153

a	=	?
b	=	?
c	=	?

adr = 25
cr	= 13
lf	= 10

par	= ?
retadr	=	?
ptr	= ?

init
		ld	adr
		add	1
		st	ptr
start
		ld	(serial+1)
		and	2
		bz	start
		ld	(serial)
		st	a
		st	(ptr)
		ld	ptr
		add	1
		st	ptr

		jp	ser_out
		ld	a
		sub	cr
		bnz	start

		ld	lf
		st	a
		jp	ser_out

pali
		ld	(ptr)
		st	a
		jp	ser_out

		ld	ptr
		sub	1
		st	ptr
		sub	adr
		bnz	pali
		
		ld	cr
		st	a
		jp	ser_out
		ld	lf
		st	a
		jp	ser_out

		jp	init

//
//	write one character to serial line 
//
ser_out
		st	retadr
wait
		ld	(serial+1)
		and	1
		bz	wait
		ld	a
		st	(serial)
		jp	(retadr)