; CPU configuration
	processor 16f84
	include	  <p16f84.inc>
	__config  _HS_OSC & _WDT_OFF & _PWRTE_ON

; memory map
; ----------
; 20 time <- start
; 21 length
; 22 curmap
; ...
; 30 map 0 size <- map sizes block start
; 31 map 1 size
; 32 map 2 size
; ...
; 40  <- event maps
;  } map 0 events
; 50  
;  } map 1 events
; 60 
;  } map 2 events
; 70 ...
; ...

#define BUTTON_PIN 	0
#define MAP_SIZES_ADDR	30
#define MAP_ADDR	40

time	equ	H'20'
length	equ	H'21'
curmap	equ	H'22'
temp	equ	H'23'

; state
#define STATE_DEBOUNCE	0
state	equ	H'23'

; Program

start:	
	movlw	B'00000000'	
	tris	PORTA		; init port A as output
	movlw	B'11111111'	
	tris	PORTB		; init port B as input
	bsf	PORTA, 0x02	; init midi out pin state 

	; init
	clrf	time
	clrf	curmap
	clrf	state
	movlw	D'10'
	movwf	length

	; init map sizes
	; todo - only one map for now
	clrf	MAP_SIZES_LOC

mainloop:
	incf	time		; increment time
	movf	length, w	; load the total length
	subwf	time,w		; time-length
	skpnc			; skip on no carry	
	clrf	time		; reset clock to start of loop	

	call	checkinput

	; check button
	; set event if necc
	; check maps
	goto	mainloop

;----------------------------------------------------------------
; read the input bit
checkinput:
	btfss	PORTB,BUTTON_PIN	; skip if button down
	clrf	state,STATE_DEBOUNCE	; clear the debounce state (button up)

	btfsc	state,STATE_DEBOUNCE	; skip if debounce is clear
	return				; exit if pressed last time and still down

	btfss	PORTB,BUTTON_PIN	; skip if set
	return				; exit if not pressed
	bsf	state,STATE_DEBOUNCE	; set debounce state (we're pressed)
	
	; todo - only one map for now
	incf	MAP_SIZES_ADDR		; inc map size
	movfw	MAP_SIZES_ADDR		; load contents of the first size
	addwf	MAP_LOC,w		; add size to map top to get dest addr
	movwf	temp			; put addr in temp
	movf	time,

	return

;----------------------------------------------------------------

; send a midi event if the time is right, checking all maps
sendevents:
	return

;----------------------------------------------------------------
; send a midi event now!
send:	
	movlw	0x90		; note on, channel 1
	movwf	xmit
	call	sendmidi
	
	movlw	0x3C		; middle C
	movwf	xmit
	call	sendmidi

	movlw	0x7F		; velocity 127
	movwf	xmit
	call	sendmidi

;	movlw	0x80		; note off, channel 1
;	movwf	xmit
;	call	sendmidi
	
;	movlw	0x3C		; middle C
;	movwf	xmit
;	call	sendmidi

;	movlw	0x7F		; velocity 127
;	movwf	xmit
;	call	sendmidi

	return

;----------------------------------------------------------------------

; secdelay delays for one second ( 2500000 instructions )
; kloop = (2 + 254 * 3 + 1 * 2) = 766
; jloop = 2 + kloop * 255 + (3 * 254 + 1 * 2) = 196096
; iloop = 2 + jloop * 13 + (3*254 + 1*2) = 2550014 = 1.02 seconds
; x = 
secdelay:
	movlw	D'13'
	movwf	i
iloop:	movlw	D'255'
	movwf	j
jloop:	movlw	D'255'
	movwf	k
kloop:	decfsz	k,f
	goto	kloop
	decfsz	j,f
	goto	jloop
	decfsz	i,f
	goto	iloop
	return


include "midi.inc"

end