add sound command

this behives the same as BASIC

sound(voice, pitch, distortion, volume)

include/atari.h

@@ -235,6 +235,12 @@ extern void __fastcall__ _scroll (signed char numlines);
                                           /* numlines < 0  scrolls down */
 
 
+/*****************************************************************************/
+/*    Sound function                                                         */
+/*****************************************************************************/
+
+extern void  __fastcall__ sound (unsigned char voice, unsigned char frequency, unsigned char distortion, unsigned char volume);  /* plays a sound in the specidied voice, to silence call with in other params*/
+
 /*****************************************************************************/
 /* Misc. functions                                                           */
 /*****************************************************************************/

libsrc/atari/sound.s

@@ -0,0 +1,43 @@
+;
+; 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