UARTDriver.h

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#pragma once

#include <stdint.h>

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

/* Pure virtual UARTDriver class */
class AP_HAL::UARTDriver : public AP_HAL::BetterStream {
public:
    UARTDriver() {}
    virtual void begin(uint32_t baud) = 0;
    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;

    // lock a port for exclusive use. Use a key of 0 to unlock
    virtual bool lock_port(uint32_t key) { return false; }

    // write to a locked port. If port is locked and key is not correct then 0 is returned
    // and write is discarded
    virtual size_t write_locked(const uint8_t *buffer, size_t size, uint32_t key) { return 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; }

    virtual void configure_parity(uint8_t v){};
    virtual void set_stop_bits(int n){};

    /* unbuffered writes bypass the ringbuffer and go straight to the
     * file descriptor
     */
    virtual bool set_unbuffered_writes(bool on){ return false; };

    /*
      wait for at least n bytes of incoming data, with timeout in
      milliseconds. Return true if n bytes are available, false if
      timeout
     */
    virtual bool wait_timeout(uint16_t n, uint32_t timeout_ms) { return false; }

    /*
     * Optional method to control the update of the motors. Derived classes
     * can implement it if their HAL layer requires.
     */
    virtual void _timer_tick(void) { }

    /*
      return timestamp estimate in microseconds for when the start of
      a nbytes packet arrived on the uart. This should be treated as a
      time constraint, not an exact time. It is guaranteed that the
      packet did not start being received after this time, but it
      could have been in a system buffer before the returned time.

      This takes account of the baudrate of the link. For transports
      that have no baudrate (such as USB) the time estimate may be
      less accurate.

      A return value of zero means the HAL does not support this API
     */
    virtual uint64_t receive_time_constraint_us(uint16_t nbytes) { return 0; }
};