revert sn76489

Source/HBIOS/audio.inc

@@ -34,4 +34,42 @@
 
 #IFNDEF AUDIOUTILS
 #DEFINE AUDIOUTILS
+
+AUD_NOTE:
+	AUDDEBUG("AUDNOTE ")
+	AUDTRACE_HL
+	AUDTRACE_CR
+	AUDTRACE_DE
+	AUDTRACE_CR
+
+	push	de
+	LD	DE, 48
+	CALL	DIV16
+					; BC IS OCTAVE COUNT
+					; HL is NOTE WITIN OCTAVE
+	ADD	HL, HL
+	pop	de
+	ADD	HL, DE
+
+	LD	A, (HL)			; RETRIEVE PERIOD COUNT FROM SN7NOTETBL
+	INC	HL
+	LD	H, (HL)
+	LD	L, A
+
+	INC	C
+AUD_NOTE1:
+	DEC	C
+	JR	Z, AUD_NOTE2
+	SRL	H
+  	RR	L
+	JR	AUD_NOTE1
+
+AUD_NOTE2:
+	LD	A, L			; IF NOT ZERO
+	OR	H
+	RET	NZ			; RETURN THE CALCULATED PERIOD
+
+	LD	H, $FF			; OTHERWISE RETURN -1 PERIOD (ERROR)
+	LD	L, $FF
+	RET
 #ENDIF