Update ym2612.asm

Source/HBIOS/ym2612.asm

@@ -51,9 +51,6 @@ YM_FNTBL:	.DW	YM_RESET
 ;
 YM_IDAT	.EQU	0				; NO INSTANCE DATA FOR THIS DEVICE
 ;
-YM_DURATION
-		ret
-
 ;------------------------------------------------------------------------------
 ; YM2162 Initialization
 ;	Announce device on console. 
@@ -252,6 +249,14 @@ YM_PERIOD1:	LD	A, $FF			; REQUESTED PERIOD IS LARGER
 		RET				; AND RETURN FAILURE
 ;
 ;------------------------------------------------------------------------------
+;	SOUND DRIVER FUNCTION - DURATION
+;------------------------------------------------------------------------------
+;
+YM_DURATION:	LD	(YM_PENDING_DURATION),HL	; SET TONE DURATION
+		XOR	A
+		RET
+;
+;------------------------------------------------------------------------------
 ; Sound driver function - PLAY
 ;	D = CHANNEL
 ;------------------------------------------------------------------------------