;
; Mariano Domínguez
; 2022-12-4
;
; atari lib
;
        .include "atari.inc"
        .export         _sound
        .import         popa
; play sound, arguments: voice, pitch, distortion, volume. same as BASIC
.proc   _sound
        sta STORE2      ;save volume
        jsr popa        ;get distortion
        sta STORE1      ;save distortion
        jsr popa        ;get pitch
        pha             ;save in stack
        jsr popa        ;get voice
        asl a           ;adjust voice *2 for offset in x
        tax
        pla             ;get pitch from stack
        sta AUDF1,x     ;store pitch
        lda #0
        sta AUDCTL
        lda #3
        stx SKCTL       ;init sound
        lda STORE1      ;get distortion
        asl a           ;ignore the high nibble
        asl a
        asl a
        asl a
        clc             ;setup for adding volume
        adc STORE2      ;add volume
        sta AUDC1,x     ;volume + distortion in control channel
        rts
.endproc
                        ;reserve 2 bytes for temp storage
        .bss
STORE1: .res    1
STORE2: .res    1