Update audio.inc

Commentry

Source/HBIOS/audio.inc

@@ -41,25 +41,25 @@ AUD_NOTE:
 	AUDTRACE_CR
 	AUDTRACE_DE
 	AUDTRACE_CR
+;
+	PUSH	DE			; ON ENTRY HL IS THE NOTE TO PLAY
+	LD	DE, 48			; AND DE IS THE START OF NOTE TABLE
+	CALL	DIV16			; LOAD DE WITH NOTE TABLE SIZE
+					; AND CALCULATE OCTAVE COUNT IN BC
 
-	push	de
-	LD	DE, 48
-	CALL	DIV16
-					; BC IS OCTAVE COUNT
-					; HL is NOTE WITIN OCTAVE
-	ADD	HL, HL
-	pop	de
-	ADD	HL, DE
+	ADD	HL, HL			; HL IS THE REMAINDER FROM ABOVE DIVISION (0-47) AND THE NOTE 
+	POP	DE			; TO PLAY IN THE OCTAVE. ADD IT TO THE START OF THE NOTE TABLE
+	ADD	HL, DE			; TO POINT TO THE PERIOD FOR THE NOTE WE WANT TO PLAY.
 
-	LD	A, (HL)			; RETRIEVE PERIOD COUNT FROM SN7NOTETBL
-	INC	HL
-	LD	H, (HL)
+	LD	A, (HL)			; HL POINT TO CURRENT PERIOD COUNT WE WANT TO PLAY
+	INC	HL			; SO LOAD PERIOD COUNT FROM NOTE TABLE INTO HL
+	LD	H, (HL)			; SO WE CAN UPDATE IT FOR THE REQUIRED OCTAVE
 	LD	L, A
 
 	INC	C
-AUD_NOTE1:
-	DEC	C
-	JR	Z, AUD_NOTE2
+AUD_NOTE1:				; DIVIDE THE PERIOD
+	DEC	C			; BY TWO
+	JR	Z, AUD_NOTE2		; FOR EACH OCTAVE
 	SRL	H
   	RR	L
 	JR	AUD_NOTE1
@@ -69,7 +69,8 @@ AUD_NOTE2:
 	OR	H
 	RET	NZ			; RETURN THE CALCULATED PERIOD
 
-	LD	H, $FF			; OTHERWISE RETURN -1 PERIOD (ERROR)
-	LD	L, $FF
+	CPL	
+	LD	H, A			; OTHERWISE RETURN -1 PERIOD (ERROR)
+	LD	L, A
 	RET
 #ENDIF