Using available defines/constants instead of hardcoded values for linestate

Author: aentinger

cores/arduino/USB/CDC.cpp

@@ -119,7 +119,7 @@ bool CDC_Setup(USBSetup &setup)
 			// auto-reset into the bootloader is triggered when the port, already
 			// open at 1200 bps, is closed. We check DTR state to determine if host
 			// port is open (bit 0 of lineState).
-			if (_usbLineInfo.dwDTERate == 1200 && (_usbLineInfo.lineState & 0x01) == 0)
+			if (_usbLineInfo.dwDTERate == 1200 && (_usbLineInfo.lineState & CDC_LINESTATE_DTR) == 0)
 			{
 				initiateReset(250);
 			}
@@ -278,12 +278,12 @@ uint8_t Serial_::numbits()
 
 bool Serial_::dtr()
 {
-	return _usbLineInfo.lineState & 0x1;
+	return _usbLineInfo.lineState & CDC_LINESTATE_DTR;
 }
 
 bool Serial_::rts()
 {
-	return _usbLineInfo.lineState & 0x2;
+	return _usbLineInfo.lineState & CDC_LINESTATE_RTS;
 }
 
 // This operator is a convenient way for a sketch to check whether the