Update usbfifo.asm

Add cable disconnect recognition

Source/HBIOS/usbfifo.asm

@@ -13,9 +13,12 @@
 ;	UF_PREINIT	SETUP THE DISPATCH TABLE ENTRY AND INITIALIZE HARDWARE	
 ;	UF_INIT		ANNOUNCE DEVICE DESCRIPTION AND PORT
 ;
-FIFO_DATA       .EQU	(FIFO_BASE+0)
-FIFO_STATUS     .EQU	(FIFO_BASE+1)
-FIFO_SEND_IMM   .EQU	(FIFO_BASE+2)
+FIFO_DATA       .EQU	(FIFO_BASE+0)	; READ/WRITE DATA
+FIFO_STATUS     .EQU	(FIFO_BASE+1)	; READ/WRITE STATUS
+FIFO_SEND_IMM   .EQU	(FIFO_BASE+2)	; WRITE PORT TO FORCE BUFFER FLUSH
+FIFO_BUFFER	.EQU	FALSE		; OPTION TO BUFFER OUTPUT FOR 17ms
+;
+UF_USB_ACTIVE	.DB	0		; USB CABLE CONNECTED STATUS FLAG
 ;
 ; DEVICE DESCRIPTION TABLE
 ;
@@ -29,7 +32,9 @@ UF_PREINIT:
 	PUSH	HL
 	POP	IY			; ... TO IY
 	CALL	UF_INITUNIT		; HAND OFF TO GENERIC INIT CODE
+	LD	(UF_USB_ACTIVE),A	; SAVE USB CONNECTION STATUS
 	POP	DE			; GET ENTRY ADDRESS BACK, BUT PUT IN DE
+;	JR	Z,UF_FAIL		; EXIT IF NO USB CONNECTION
 	LD	BC,UF_FNTBL		; BC := FUNCTION TABLE ADDRESS
 	CALL	CIO_ADDENT		; ADD ENTRY IF FOUND, BC:DE
 	XOR	A			; SIGNAL SUCCESS
@@ -53,8 +58,12 @@ UF_INIT:
 	CALL	NEWLINE			; PRINT DEVICE
 	PRTS("USB-FIFO: $")
 	PRTS("IO=0x$")
-	LD	A,FIFO_BASE
-	CALL	PRTHEXBYTE		; PRINT PORT
+	LD	A,FIFO_BASE		; PRINT PORT
+	CALL	PRTHEXBYTE
+	LD	A,(UF_USB_ACTIVE)	; PRINT CABLE STATUS
+	OR	A
+	RET	NZ
+	PRTS(" No Cable$")
 	RET
 ;
 ; INPUT A CHARACTER AND RETURN IT IN E
@@ -74,7 +83,9 @@ UF_OUT:
 	JR	Z,UF_OUT		; LOOP IF NOT
 	LD	C,FIFO_DATA
 	OUT	(C),E			; WRITE TO FIFO
+#IF (FIFO_BUFFER)
 	OUT	(FIFO_SEND_IMM),A	; SEND IMMEDIATE
+#ENDIF
 	XOR	A			; SIGNAL SUCCESS
 	RET
 ;
@@ -147,11 +158,11 @@ UF_DEVICE:
 ; USB-FIFO DETECTION ROUTINE
 ;
 UF_DETECT:
-;	IN	A,(FIFO_STATUS)		; DON'T LOAD DRIVER IF	
-;	AND	10000001B		; CABLE DISCONNECTED
-;	SUB	10000001B		; A=0 
-;	RET	Z
-	LD	A,1			; A=1
+	IN	A,(FIFO_STATUS)
+	AND	10000001B
+	SUB	10000001B		; A=0 CABLE DISCONNECTED
+	RET	Z
+	LD	A,1			; A=1 CABLE CONNECTED
 	RET
 ;
 ; DRIVER FUNCTION TABLE