#include "via6522.i65"

#define   VIA1      $e840

#define	BELLIRQ		jsr bellirq

#define	TRIGBELL	jsr trigbell


/**************************************************************************
 * Bell handling
 */

          .(
          
	.data
pnt       .byt 0
cnt       .byt 0
	.text

&inibell  
	  lda #%00100100
          sta VIA1+VIA_IER
          lda VIA1+VIA_ACR
          and #%11000011
          ora #%00010000
          sta VIA1+VIA_ACR
&&trigbell 
	  lda #0
          sta pnt
          sta cnt
          lda #15
          sta VIA1+VIA_SR
&&bellirq  
	  lda cnt
          bne endirq
          ldy pnt
          lda tcnt,y
          beq endbell
          sta cnt
          lda tfrq,y
          sta VIA1+VIA_T2CL
          lda #0
          sta VIA1+VIA_T2CH
          inc pnt
endirq    dec cnt
          rts
endbell   lda #0
          sta VIA1+VIA_SR
          rts
          
tcnt      .byt 2,2,2,2,2,2,2,0
tfrq      .byt 32,64,128,32,64,128,32

          .)