CSerialPort.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2020, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */
#pragma once

#include <mrpt/io/CStream.h>
#include <mrpt/system/CTicTac.h>

namespace mrpt::comms
{
/** A communications serial port built as an implementation of a utils::CStream.
 * On communication errors (eg. the given port number does not exist,
 * timeouts,...), most of the methods will
 * raise an exception of the class `std::exception`
 *
 *  The serial port to open is passed in the constructor in the form of a string
 * description, which is platform dependent.
 *
 *  In Windows they are numbered "COM1"-"COM4" and "\\.\COMXXX" for numbers
 * above. It is recomended to always use the prefix "\\.\" despite the actual
 * port number.
 *
 *  In Linux the name must refer to the device, for example: "ttyUSB0","ttyS0".
 * If the name string does not start with "/" (an absolute path), the
 * constructor will assume the prefix "/dev/".
 *
 *  History:
 *    - 1/DEC/2005:  (JLBC) First version
 *    - 20/DEC/2006: (JLBC) Integration into the MRPT framework
 *    - 12/DEC/2007: (JLBC) Added support for Linux.
 *    - 22/AUG/2017: (JLBC) Moved to new module mrpt-comms
 *
 * \todo Add the internal buffer to the Windows implementation also
 * \ingroup mrpt_comms_grp
 */
class CSerialPort : public mrpt::io::CStream
{
    friend class PosixSignalDispatcherImpl;

   public:
    /** Constructor
     * \param portName The serial port to open. See comments at the begining of
     * this page.
     * \param openNow Whether to try to open the port now. If not selected, the
     * port should be open later with "open()".
     *
     */
    CSerialPort(const std::string& portName, bool openNow = true);

    /** Default constructor: it does not open any port - later you must call
     * "setSerialPortName" and then "open"
     */
    CSerialPort() = default;

    /** Destructor
     */
    ~CSerialPort() override;

    /** Sets the serial port to open (it is an error to try to change this while
     * open yet).
     * \sa open, close
     */
    void setSerialPortName(const std::string& COM_name);

    /** Open the port. If is already open results in no action.
     * \exception std::exception On communication errors
     */
    void open();

    /** Open the given serial port. If it is already open and the name does not
     * match, an exception is raised.
     * \exception std::exception On communication errors or a different serial
     * port already open.
     */
    void open(const std::string& COM_name);

    /** Close the port. If is already closed, results in no action.
     */
    void close();

    /** Returns if port has been correctly open.
     */
    bool isOpen() const;

    /** Purge tx and rx buffers.
     * \exception std::exception On communication errors
     */
    void purgeBuffers();

    /** Changes the configuration of the port.
     *  \param parity  0:No parity, 1:Odd, 2:Even (WINDOWS ONLY: 3:Mark,
     * 4:Space) \param baudRate The desired baud rate Accepted values: 50 -
     * 230400 \param bits Bits per word (typ. 8) Accepted values: 5,6,7,8.
     *  \param nStopBits Stop bits (typ. 1) Accepted values: 1,2
     *  \param enableFlowControl Whether to enable the hardware flow control
     * (RTS/CTS) (default=no)
     * \exception std::exception On communication errors
     */
    void setConfig(
        int baudRate, int parity = 0, int bits = 8, int nStopBits = 1,
        bool enableFlowControl = false);

    /** Changes the timeouts of the port, in milliseconds.
     * \exception std::exception On communication errors
     */
    void setTimeouts(
        int ReadIntervalTimeout, int ReadTotalTimeoutMultiplier,
        int ReadTotalTimeoutConstant, int WriteTotalTimeoutMultiplier,
        int WriteTotalTimeoutConstant);

    /** Implements the virtual method responsible for reading from the stream -
     * Unlike CStream::ReadBuffer, this method will not raise an exception on
     * zero bytes read, as long as there is not any fatal error in the
     * communications.
     * \exception std::exception On communication errors
     */
    size_t Read(void* Buffer, size_t Count) override;

    /** Reads one text line from the serial port in POSIX "canonical mode".
     *  This method reads from the serial port until one of the characters in
     * \a eol are found.
     * \param eol_chars A line reception is finished when one of these
     * characters is found. Default: LF (10), CR (13).
     * \param total_timeout_ms If >0, the maximum number of milliseconds to
     * wait.
     * \param out_timeout If provided, will hold true on return if a timeout
     * ocurred, false on a valid read.
     * \return The read string, without the final
     * \exception std::exception On communication errors
     */
    std::string ReadString(
        const int total_timeout_ms = -1, bool* out_timeout = nullptr,
        const char* eol_chars = "\r\n");

    // See base class docs
    size_t Write(const void* Buffer, size_t Count) override;
    /** not applicable in a serial port */
    uint64_t Seek(
        int64_t off, CStream::TSeekOrigin o = sFromBeginning) override;
    /** not applicable in a serial port */
    uint64_t getTotalBytesCount() const override;
    /** not applicable in a serial port */
    uint64_t getPosition() const override;

   protected:
    /** The complete name of the serial port device (i.e.
     * "\\.\COM10","/dev/ttyS2",...)
     */
    std::string m_serialName;
    int m_baudRate{0};
    int m_totalTimeout_ms{0}, m_interBytesTimeout_ms{0};
    mrpt::system::CTicTac m_timer;
#ifdef _WIN32
    // WINDOWS
    void* hCOM{nullptr};
#else
    // LINUX
    /** The file handle (-1: Not open)
     */
    int hCOM{-1};
#endif
};  // end of class
}  // namespace mrpt::comms