add sound command

this behives the same as BASIC sound(voice, pitch, distortion, volume)
2023-01-05 21:12:58 -08:00
parent e944a30b6a
commit f9024d132a
2 changed files with 49 additions and 0 deletions
--- a/libsrc/atari/sound.s
+++ b/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