Happy birthday - Assembler mega32

;Assembler program for Mega32 (Atmel), play music with 8 switchs(btn) "Happy birthday" song
;*********** INITIALIZING**********
; The frequency is 3.6864 MHz.
.include "M32DEF.INC"
   LDI  R16,HIGH(RAMEND)  ;Initialize Stack Pointer
   OUT  SPH,R16
   LDI  R16,LOW(RAMEND)
   OUT  SPL,R16

   SER  R16
   OUT  DDRB,R16          ;The PB pins are outputs

   LDI R16,0x00
   OUT DDRA,R16		;The PA pins are inputs

   NOP ; Synchronyzer delay

;********** PROGRAM LOOP **********
HERE:

	SBIS PINA,0
	LDI R18,239

	SBIS PINA,1
	LDI R18,213

	SBIS PINA,2
	LDI R18,190

	SBIS PINA,3
	LDI R18,179

	SBIS PINA,4
	LDI R18,160

	SBIS PINA,5
	LDI R18,142

	SBIS PINA,6
	LDI R18,135

	SBIS PINA,7
	LDI R18,120

	// Read whole PINA
	IN R20, PINA
	// If PINA == 255 then jump.
	CPI R20, 0xFF
	BREQ HERE

	// Play the sound on PORTB.
	COM R16
	OUT PORTB, R16

	CALL DELAY


   RJMP HERE

;********* DELAY (R18*4us) ********
DELAY:
   LDI  R17,4
AGAIN:
   DEC  R17
   BRNE AGAIN
   DEC  R18
   BRNE DELAY
   RET
;**********************************