# heartbeat demo from Hauppauge 4860 motherboard docs


delay_count = 1000000
iobase = 0xF8000000

# .atmp r31   # always r31 in ATT syntax
.text

	nop

	.globl		_start
_start:

	st.c		%r0,%psr
	st.c		%r0,%fsr
	ld.c		%fir,%r0

# clear pipeline

	pfadd.ss	%f0,%f0,%f0
	pfadd.ss	%f0,%f0,%f0
	pfadd.ss	%f0,%f0,%f0
	pfmul.ss	%f0,%f0,%f0
	pfmul.ss	%f0,%f0,%f0
	pfmul.ss	%f0,%f0,%f0

	mov	iobase, %r4

loop:
	#call		delay
	# nop

	call	getlink		# (watch following delay slot!)
	 shl	%r0, %r4, %r16	# mov r4, r16 - save base(?)address
	 
	addu	1, %r16, %r17	# add 1 and into r17
	
	call	putlink		# (watch following delay slot!)
	 shl	%r0, %r4, %r16	# mov r4, r16 - save base(?)address 

	br		loop
	 nop

	 
# Read a byte from the C012

getlink:
		ld.b	0x17(%r16), %r17	# Read C012 Output Status
		and	1, %r17, %r0	# if "0" (No Data) set carry
		st.b	%r0, 0(%r0)		# dummy store
		nop	
		bc	getlink
		ld.b	7(%r16), %r16
		st.b	%r0, 0(%r0)		# dummy store
		nop
		bri	%r1		# return sub (watch following delay slot!)
		 and	0xFF, %r16, %r16	# return data in r16, remove sign 
# End of function getlink



# Write a byte from the C012

putlink:
		ld.b	0x1F(%r16), %r20	# Read C012 Input Status
		and	1, %r20, %r0	# if "0" (Not Ready) set carry
		st.b	%r0, 0(%r0)		# dummy store
		nop
		bc	putlink		# loop if carry set (not ready)
		st.b	%r0, 0(%r0)		# dummy store
		nop
		bri	%r1		# return sub (watch following delay slot!)
		 st.b	%r17,0xF(%r16)	# Write byte from r17 into 0xF  
# End of function putlink

	.end