ez80uart: defer basic i/o operations to ez80 firmware

Source/HBIOS/ez80uart.asm

@@ -43,36 +43,28 @@ EZUART_INIT:
 
 ; RETRIEVE THE NEXT CHARACTER FROM THE UART AND RETURN IN E
 EZUART_IN:
-	IN0_A	(UART0_LSR)		; CHECK FOR RX READY
-	AND	LSR_DR
-	JR	Z, EZUART_IN
-	
-	IN0_E	(UART0_RBR)		; GET THE CHAR
-
-	XOR	A			; SIGNAL SUCCESS
+	LD	A, 3			; UART
+	LD	B, 0			; UART-IN
+	EZ80_FN				; CHAR RETURNED IN E
 	RET
 	
 ; OUT CHAR IN E
 EZUART_OUT:
-	IN0_A	(UART0_LSR)		; WAIT FOR TX READY
-	AND	LSR_THRE
-	JR	Z, EZUART_OUT
-     
-	OUT0_E	(UART0_THR)		; SEND THE CHAR
-
-	XOR	A			; SIGNAL SUCCESS
+	LD	A, 3			; UART
+	LD	B, 1			; UART-OUT
+	EZ80_FN
 	RET
 
 EZUART_IST:
-	IN0_A	(UART0_LSR)		; CHECK FOR RX READY
-	AND	LSR_DR
+	LD	A, 3			; UART
+	LD	B, 2			; UART-IST
+	EZ80_FN
 	RET
 
 EZUART_OST:
-	IN0_A	(UART0_LSR)		; WAIT FOR TX READY
-	AND	LSR_THRE
-	RET	Z
-	LD	A, 1
+	LD	A, 3			; UART
+	LD	B, 3			; UART-OST
+	EZ80_FN
 	RET
 
 EZUART_INITDEV: