;
; CPU Init module
;
; Initialize all MPU registers and return to calling routine
;
; Trashes R1
;
; Assumes the various .SET symbols have been updated with the 
; appropriate bits needed to initialize the MPU
; 
; For the 1200 many init's are simple bit sets.  I use whole register
; writes for consistency and compatibility with upscale processors (e.g. 8515)
;
; Once conditional assembly is available, many of the following could be
; not included if no bits are set.
;
cpu_init:
	clr	R31			; Zero all registers
	ldi	ZL, 29
cpu_1:	st	Z, R31
	dec	ZL
	brge	cpu_1
	clr	ZL

	ldi	I_tmp, PORTD_INIT	; set output state before direction.
	out	PORTD, I_tmp		; at reset output is low, direction is in.
	ldi	I_tmp, DDRD_INIT
	out	DDRD, I_tmp
	ldi	I_tmp, PORTB_INIT	; ditto
	out	PORTB, I_tmp
	ldi	I_tmp, DDRB_INIT
	out	DDRB, I_tmp

	ldi	I_tmp, ACSR_INIT	; Analog Interrupt Mask
	out	ACSR, I_tmp

	ldi	I_tmp, TCNT0_INIT
	out	TCNT0, I_tmp
	ldi	I_tmp, TCCR0_INIT
	out	TCCR0, I_tmp
	ldi	I_tmp, TIMSK_INIT	; yeah, this is just a bit set...
	out	TIMSK, I_tmp

	ldi	I_tmp, MCUCR_INIT	; set up sleep mode & Extn interrupt
	out	MCUCR, I_tmp

	ldi	I_tmp, WDTCR_INIT	; Watch Dog...
	out	WDTCR, I_tmp

	ldi	I_tmp, GIMSK_INIT	; External Interrupt mask
	out	GIMSK, I_tmp

	ldi	I_tmp, SREG_INIT
	out	SREG, I_tmp		; enable interrupts

	ret