#include "P18F4455.INC"

ORG	0X800

VAR0	EQU		0X00
VAR1	EQU		0X01
TMP		EQU		0X02
COUNTER EQU		0X03

FULL_NOTE	EQU		D'150'
HALF_NOTE	EQU		D'80'
PAUSE_NOTE	EQU		D'10'
LONG_PAUSE	EQU		D'200'

CBLOCK	0X00
	_DO_
	_RE_
	_MI_
	_FA_
	_SOL_
	_LA_
	_SI_
	_DO_UP_
ENDC

;C4 - F = 262 Hz, T = 3.8167 mSec, T/2 = 1.9083
;D4 - F = 294 Hz, T = 3.4013 mSec, T/2 = 1.7006
;E4 - F = 330 Hz, T = 3.0303 mSec, T/2 = 1.5151
;F4 - F = 349 Hz, T = 2.8653 mSec, T/2 = 1.4326
;G4 - F = 392 Hz, T = 2.5510 mSec, T/2 = 1.2755
;A4 - F = 440 Hz, T = 2.2727 mSec, T/2 = 1.13635
;B4 - F = 494 Hz, T = 2.0246 mSec, T/2 = 1.0123
;C4 - F = 524 Hz, T = 1.9110 mSec, T/2 = 0.9555

	GOTO	MAIN

Get_Next_Note:
	MULLW	D'2'
	MOVF	PRODL, W
	MOVFF	PCL, TMP
	ADDWF	PCL, F
	RETLW	_DO_
	RETLW	_MI_
	RETLW	_DO_
	RETLW	_MI_
	RETLW	_SOL_
	RETLW	_SOL_
	RETLW	_DO_
	RETLW	_MI_
	RETLW	_DO_
	RETLW	_MI_
	RETLW	_SOL_
	RETLW	_SOL_
	RETLW	_DO_UP_
	RETLW	_SI_
	RETLW	_LA_
	RETLW	_SOL_
	RETLW	_FA_
	RETLW	_LA_
	RETLW	_SOL_
	RETLW	_FA_
	RETLW	_MI_
	RETLW	_RE_
	RETLW	_DO_
	RETLW	_DO_

Get_Next_Delay:
	MULLW	D'2'
	MOVF	PRODL, W
	MOVFF	PCL, TMP
	ADDWF	PCL, F
	RETLW	HALF_NOTE
	RETLW	HALF_NOTE
	RETLW	HALF_NOTE
	RETLW	HALF_NOTE
	RETLW	FULL_NOTE
	RETLW	FULL_NOTE
	RETLW	HALF_NOTE
	RETLW	HALF_NOTE
	RETLW	HALF_NOTE
	RETLW	HALF_NOTE
	RETLW	FULL_NOTE
	RETLW	FULL_NOTE
	RETLW	HALF_NOTE
	RETLW	HALF_NOTE
	RETLW	HALF_NOTE
	RETLW	HALF_NOTE
	RETLW	FULL_NOTE
	RETLW	FULL_NOTE
	RETLW	HALF_NOTE
	RETLW	HALF_NOTE
	RETLW	HALF_NOTE
	RETLW	HALF_NOTE
	RETLW	FULL_NOTE
	RETLW	FULL_NOTE

Get_Next_Period:
	MULLW	D'2'
	MOVF	PRODL, W
	MOVFF	PCL, TMP
	ADDWF	PCL, F
	RETLW	D'237'
	RETLW	D'211'
	RETLW	D'188'
	RETLW	D'178'
	RETLW	D'158'
	RETLW	D'141'
	RETLW	D'127'
	RETLW	D'118'

Get_Next_DutyCycle:
	MULLW	D'2'
	MOVF	PRODL, W
	MOVFF	PCL, TMP
	ADDWF	PCL, F
	RETLW	D'29'
	RETLW	D'70'
	RETLW	D'65'
	RETLW	D'60'
	RETLW	D'55'
	RETLW	D'50'
	RETLW	D'40'
	RETLW	D'35'

DELAY_1MILLI
	MOVLW	D'200'
	MOVWF	VAR0
LOOP1:
	NOP
	NOP
	NOP
	NOP
	DECFSZ	VAR0,F
	GOTO	LOOP1
	RETURN

VARIABLE_DELAY:
	MOVWF	VAR1
LOOP2:
	CALL	DELAY_1MILLI
	CALL	DELAY_1MILLI
	CALL	DELAY_1MILLI
	CALL	DELAY_1MILLI
	DECFSZ	VAR1,F
	GOTO	LOOP2
	RETURN

NO_SOUND:
	MOVLW	D'255'
	MOVWF	CCPR2L
	MOVLW	PAUSE_NOTE
	MOVWF	VAR1
	CALL	VARIABLE_DELAY
	RETURN

NO_SOUND_LONG_PAUSE:
	MOVLW	D'255'
	MOVWF	CCPR2L
	MOVLW	LONG_PAUSE
	MOVWF	VAR1
	CALL	VARIABLE_DELAY
	RETURN

MAIN:
	; select internal 4 MHz oscilator
	MOVLW	B'01100010'
	MOVWF	OSCCON

	CLRF	TRISB
	CLRF	TRISC
	MOVLW	0X0F
	MOVWF	ADCON1
	MOVLW	0X07
	MOVWF	CMCON
	CLRF	COUNTER

	MOVLW	B'00000111'
	MOVWF	T2CON

	; set PWM mode
	MOVLW	B'00001111'
	MOVWF	CCP2CON

	BCF		CCP2CON, 5	; upper bit is set to 0
	BCF		CCP2CON, 4

MAIN_LOOP:

	MOVF	COUNTER, W

	; GET NEXT NOTE TO BE PLAYED
	CALL	Get_Next_Note
	CALL	Get_Next_Period
	MOVWF	PR2

	MOVF	COUNTER, W

	; GET NEXT NOTE TO BE PLAYED
	CALL	Get_Next_Note
	CALL	Get_Next_DutyCycle
	MOVWF	CCPR2L

	BCF		CCP2CON, 4	
	TSTFSZ	COUNTER
	GOTO	START_DELAY
	BSF		CCP2CON, 4

START_DELAY:
	MOVF	COUNTER, W
	
	; GET NEXT NOTE LENGTH
	CALL	Get_Next_Delay
	MOVWF	VAR1
	CALL	VARIABLE_DELAY

	; NO SOUND
	CALL	NO_SOUND

	; MOVE TO NEXT NOTE
	INCF	COUNTER, F

	MOVLW	D'24'
	CPFSEQ	COUNTER
	GOTO	MAIN_LOOP

	CLRF	COUNTER

	CALL	NO_SOUND_LONG_PAUSE

	GOTO	MAIN_LOOP

	END