;****************************************
;   Elmar Kresse 19-INB-1 (2021)
;   sound.asm
;   file contains source code for
;   only playing sounds
;
;       - playbeep PROC
;source: http://muruganad.com/8086/8086-assembly-language-program-to-play-sound-using-pc-speaker.html
;****************************************


playbeep PROC
       MOV AL, 182
       OUT 43h, AL
   beep:
    
       ;set frequency
          MOV AX, [BX]
          OUT 42h, AL
          MOV AL, AH
          OUT 42h, AL
       ;sound on
          IN AL, 61h
          OR AL, 00000011b
          OUT 61h, AL

      ADD BX, 4
      MOV WORD ptr [CS:timer_ticks], 0
      
      ;break
          timer_loop:
          CMP WORD ptr [CS:timer_ticks], 3
          jne timer_loop
          MOV WORD ptr [CS:timer_ticks], 0

       ;sound off
          IN AL, 61h
          AND AL, 11111100b
          OUT 61h, AL
        
        ADD BX, 4
        SUB CX, 8
        JNE beep
        ret
playbeep ENDP