#ifndef __AP_HAL_UART_DRIVER_H__
#define __AP_HAL_UART_DRIVER_H__

#include <stdint.h>

#include "AP_HAL_Namespace.h"
#include "utility/BetterStream.h"

/*
  buffer handling macros
 */
#define BUF_AVAILABLE(buf) ((buf##_head > (_tail=buf##_tail))? (buf##_size - buf##_head) + _tail: _tail - buf##_head)
#define BUF_SPACE(buf) (((_head=buf##_head) > buf##_tail)?(_head - buf##_tail) - 1:((buf##_size - buf##_tail) + _head) - 1)
#define BUF_EMPTY(buf) (buf##_head == buf##_tail)
#define BUF_ADVANCETAIL(buf, n) buf##_tail = (buf##_tail + n) % buf##_size
#define BUF_ADVANCEHEAD(buf, n) buf##_head = (buf##_head + n) % buf##_size

/* Pure virtual UARTDriver class */
class AP_HAL::UARTDriver : public AP_HAL::BetterStream {
public:
    UARTDriver() {}
    virtual void begin(uint32_t baud) = 0;
	/// Extended port open method
	///
	/// Allows for both opening with specified buffer sizes, and re-opening
	/// to adjust a subset of the port's settings.
	///
	/// @note	Buffer sizes greater than ::_max_buffer_size will be rounded
	///			down.
	///
	/// @param	baud		Selects the speed that the port will be
	///						configured to.  If zero, the port speed is left
	///						unchanged.
	/// @param rxSpace		Sets the receive buffer size for the port.  If zero
	///						then the buffer size is left unchanged if the port
	///						is open, or set to ::_default_rx_buffer_size if it is
	///						currently closed.
	/// @param txSpace		Sets the transmit buffer size for the port.  If zero
	///						then the buffer size is left unchanged if the port
	///						is open, or set to ::_default_tx_buffer_size if it
	///						is currently closed.
	///
    virtual void begin(uint32_t baud, uint16_t rxSpace, uint16_t txSpace) = 0;
    virtual void end() = 0;
    virtual void flush() = 0;
    virtual bool is_initialized() = 0;
    virtual void set_blocking_writes(bool blocking) = 0;
    virtual bool tx_pending() = 0;

    enum flow_control {
        FLOW_CONTROL_DISABLE=0, FLOW_CONTROL_ENABLE=1, FLOW_CONTROL_AUTO=2
    };
    virtual void set_flow_control(enum flow_control flow_control_setting) {};
    virtual enum flow_control get_flow_control(void) { return FLOW_CONTROL_DISABLE; };

    /* Implementations of BetterStream virtual methods. These are
     * provided by AP_HAL to ensure consistency between ports to
     * different boards
     */
    void print_P(const prog_char_t *s);
    void println_P(const prog_char_t *s);
    void printf(const char *s, ...)
            __attribute__ ((format(__printf__, 2, 3)));
    void _printf_P(const prog_char *s, ...)
            __attribute__ ((format(__printf__, 2, 3)));

    void vprintf(const char *s, va_list ap);
    void vprintf_P(const prog_char *s, va_list ap);
};

#endif // __AP_HAL_UART_DRIVER_H__