src/platform/arm-teensy3/usb_serial.c
int usb_serial_available(void)
{
	int count;
	count = usb_rx_byte_count(CDC_RX_ENDPOINT);
	if (rx_packet) count += rx_packet->len - rx_packet->index;
	return count;
}
// number of bytes available in the receive buffer
number of bytes available in the receive buffer
number of bytes available in the receive buffer
int usb_serial_available(void)
{
	int count;
	count = usb_rx_byte_count(CDC_RX_ENDPOINT);
	if (rx_packet) count += rx_packet->len - rx_packet->index;
	return count;
}
int usb_serial_available ( void ) { int count ; count = usb_rx_byte_count ( CDC_RX_ENDPOINT ) ; if ( rx_packet ) count += rx_packet -> len - rx_packet -> index ; return count ; }
number of bytes available in the receive buffer
number of bytes available in the receive buffer