; gp is always equal to the hardware base address ($1f800000)

serial		equ	$1050		; serial port base address
serial_data	equ	serial+$0	; serial port data
serial_status	equ	serial+$4	; serial port status & bits
serial_mode	equ	serial+$8	; serial port mode & bits
serial_ctrl	equ	serial+$a	; serial port control
serial_baud	equ	serial+$e	; serial port baud rate (16-bits)
SR_CTS		equ	$100		; capslock led
SR_DSR		equ	$80		; numlock led
SR_RXRDY	equ	$2

; init keyboard serial port baud rate, etc
InitKeyboard	li	s0,$ce
		sh	s0,serial_mode(gp)
		
		li	s0,$771c
		sh	s0,serial_ctrl(gp)
		
		li	s0,$6c			; 19200 baud
		sh	s0,serial_baud(gp)
		jr	ra
		nop 

; returns key in a0, else zero!		           
ReadKey		lhu	a0,serial_status(gp)	; load the status register
		nop
		andi	a1,a0,SR_DSR		; get num lock
		sh	a1,NumLock
		andi	a1,a0,SR_CTS		; get caps lock
		sh	a1,CapsLock
		andi	a1,a0,SR_RXRDY		; is a key ready?
		beqz	a1,@Exit		; nope!
		move	a0,zero
		
		lbu	a0,serial_data(gp)	; read a byte from the serial port
		nop
		beqz	a0,@ReadKey		; next key if zero - invalid!!!
		nop
@Exit		jr	ra
		nop

NumLock		dh	0			; status of numlock light
CapsLock	dh	0			; status of capslock light