SerialPort.cpp

//!
//! @file           SerialPort.cpp
//! @author         Geoffrey Hunter <gbmhunter@gmail.com> (www.mbedded.ninja)
//! @created        2014-01-07
//! @last-modified  2023-02-13
//! @brief          The main serial port class.
//! @details
//!             See README.rst in repo root dir for more info.

// System includes
#include <iostream>
#include <sstream>
#include <stdio.h>      // Standard input/output definitions
#include <string.h>     // String function definitions
#include <unistd.h>     // UNIX standard function definitions
#include <fcntl.h>      // File control definitions
#include <errno.h>      // Error number definitions
// #include <termios.h>     // POSIX terminal control definitions (struct termios)
#include <system_error>	// For throwing std::system_error
#include <sys/ioctl.h> // Used for TCGETS2, which is required for custom baud rates
#include <cassert>
// #include <asm/termios.h> // Terminal control definitions (struct termios)
#include <asm/ioctls.h>
#include <asm/termbits.h>
#include <algorithm>
#include <iterator>

// User includes
#include "CppLinuxSerial/Exception.hpp"
#include "CppLinuxSerial/SerialPort.hpp"

#define    BOTHER 0010000

namespace mn {
namespace CppLinuxSerial {

    SerialPort::SerialPort() {
        echo_ = false;
        timeout_ms_ = defaultTimeout_ms_;
        baudRateType_ = BaudRateType::STANDARD;
        baudRateStandard_ = defaultBaudRate_;
        readBufferSize_B_ = defaultReadBufferSize_B_;
        readBuffer_.resize(readBufferSize_B_);
        state_ = State::CLOSED;
    }

    SerialPort::SerialPort(const std::string& device, BaudRate baudRate) :
            SerialPort() {
        device_ = device;
        baudRateType_ = BaudRateType::STANDARD;
        baudRateStandard_ = baudRate;
    }

    SerialPort::SerialPort(const std::string& device, speed_t baudRate) :
            SerialPort() {
        device_ = device;
        baudRateType_ = BaudRateType::CUSTOM;
        baudRateCustom_ = baudRate;
    }

    SerialPort::SerialPort(const std::string& device, BaudRate baudRate, NumDataBits numDataBits, Parity parity, NumStopBits numStopBits) :
            SerialPort() {
        device_ = device;
        baudRateType_ = BaudRateType::STANDARD;
        baudRateStandard_ = baudRate;
        numDataBits_ = numDataBits;
        parity_ = parity;
        numStopBits_ = numStopBits;
    }

    SerialPort::SerialPort(const std::string &device, BaudRate baudRate, NumDataBits numDataBits, Parity parity, NumStopBits numStopBits,
        HardwareFlowControl hardwareFlowControl, SoftwareFlowControl softwareFlowControl):
            SerialPort() {
        device_ = device;
        baudRateType_ = BaudRateType::STANDARD;
        baudRateStandard_ = baudRate;
        numDataBits_ = numDataBits;
        parity_ = parity;
        numStopBits_ = numStopBits;
        hardwareFlowControl_ = hardwareFlowControl;
        softwareFlowControl_ = softwareFlowControl;
    }

    SerialPort::~SerialPort() {
        try {
            Close();
        } catch(...) {
            // We can't do anything about this!
            // But we don't want to throw within destructor, so swallow
        }
    }

    void SerialPort::SetDevice(const std::string& device) {
        device_ = device;
        if(state_ == State::OPEN)
            ConfigureTermios();
    }

    void SerialPort::SetBaudRate(BaudRate baudRate) {
        baudRateType_ = BaudRateType::STANDARD;
        baudRateStandard_ = baudRate;
        if(state_ == State::OPEN)
            ConfigureTermios();
    }

    void SerialPort::SetBaudRate(speed_t baudRate) {
        baudRateType_ = BaudRateType::CUSTOM;
        baudRateCustom_ = baudRate;
        if(state_ == State::OPEN)
            ConfigureTermios();
    }

    void SerialPort::SetNumDataBits(NumDataBits numDataBits) {
        numDataBits_ = numDataBits;
        if(state_ == State::OPEN)
            ConfigureTermios();
    }

    void SerialPort::SetParity(Parity parity) {
        parity_ = parity;
        if(state_ == State::OPEN)
            ConfigureTermios();
    }

    void SerialPort::SetNumStopBits(NumStopBits numStopBits) {
        numStopBits_ = numStopBits;
        if(state_ == State::OPEN)
            ConfigureTermios();
    }

    void SerialPort::Open()
    {
        if(device_.empty()) {
            THROW_EXCEPT("Attempted to open file when file path has not been assigned to.");
        }

        // Attempt to open file
        //this->fileDesc = open(this->filePath, O_RDWR | O_NOCTTY | O_NDELAY);

        // O_RDONLY for read-only, O_WRONLY for write only, O_RDWR for both read/write access
        // 3rd, optional parameter is mode_t mode
        fileDesc_ = open(device_.c_str(), O_RDWR);

        // Check status
        if(fileDesc_ == -1) {
            THROW_EXCEPT("Could not open device \"" + device_ + "\". Is the device name correct and do you have read/write permissions?");
        }

        ConfigureTermios();

        // std::cout << "COM port opened successfully." << std::endl;
        state_ = State::OPEN;
    }

    void SerialPort::SetEcho(bool value) {
        echo_ = value;
        ConfigureTermios();
    }

    void SerialPort::ConfigureTermios()
    {
        //================== CONFIGURE ==================//

        // termios tty = GetTermios();
        termios2 tty = GetTermios2();

        //================= (.c_cflag) ===============//

        // Set num. data bits
        // See https://man7.org/linux/man-pages/man3/tcflush.3.html
        tty.c_cflag     &=  ~CSIZE;			// CSIZE is a mask for the number of bits per character
        switch(numDataBits_) {
            case NumDataBits::FIVE:
                tty.c_cflag     |=  CS5;
                break;
            case NumDataBits::SIX:
                tty.c_cflag     |=  CS6;
                break;
            case NumDataBits::SEVEN:
                tty.c_cflag     |=  CS7;
                break;
            case NumDataBits::EIGHT:
                tty.c_cflag     |=  CS8;
                break;
            default:
                THROW_EXCEPT("numDataBits_ value not supported!");
        }
        
        // Set parity
        // See https://man7.org/linux/man-pages/man3/tcflush.3.html
        switch(parity_) {
            case Parity::NONE:
                tty.c_cflag     &=  ~PARENB;
                break;
            case Parity::EVEN:	
                tty.c_cflag 	|=   PARENB;
                tty.c_cflag		&=	 ~PARODD; // Clearing PARODD makes the parity even
                break;
            case Parity::ODD:
                tty.c_cflag     |=   PARENB;
                tty.c_cflag		|=	 PARODD;
                break;
            default:
                THROW_EXCEPT("parity_ value not supported!");

        }

        // Set num. stop bits
        switch(numStopBits_) {
            case NumStopBits::ONE:
                tty.c_cflag     &=  ~CSTOPB;
                break;
            case NumStopBits::TWO:
                tty.c_cflag     |=  CSTOPB;
                break;
            default:
                THROW_EXCEPT("numStopBits_ value not supported!");
        }

        // Configure flow control
        switch(hardwareFlowControl_){
            case HardwareFlowControl::OFF:
                tty.c_cflag &= ~CRTSCTS;
                break;

            case HardwareFlowControl::ON: // Hardware flow control (RTS/CTS)
                tty.c_cflag |= CRTSCTS;
                break;

            default:
                // We should never get here.
                THROW_EXCEPT("flowControl_ value not supported!");
                break;
        }

        tty.c_cflag     |=  CREAD | CLOCAL; // Turn on READ & ignore ctrl lines (CLOCAL = 1)


        //===================== BAUD RATE =================//

        // We used to use cfsetispeed() and cfsetospeed() with the B... macros, but this didn't allow
        // us to set custom baud rates. So now to support both standard and custom baud rates lets
        // just make everything "custom". This giant switch statement could be replaced with a map/lookup
        // in the future
        if (baudRateType_ == BaudRateType::STANDARD) {
            tty.c_cflag &= ~CBAUD;
            tty.c_cflag |= CBAUDEX;
            switch(baudRateStandard_) {
                case BaudRate::B_0:
                    // cfsetispeed(&tty, B0);
                    // cfsetospeed(&tty, B0);
                    tty.c_ispeed = 0;
                    tty.c_ospeed = 0;
                    break;
                case BaudRate::B_50:
                    // cfsetispeed(&tty, B50);
                    // cfsetospeed(&tty, B50);
                    tty.c_ispeed = 50;
                    tty.c_ospeed = 50;
                    break;
                case BaudRate::B_75:
                    // cfsetispeed(&tty, B75);
                    // cfsetospeed(&tty, B75);
                    tty.c_ispeed = 75;
                    tty.c_ospeed = 75;
                    break;
                case BaudRate::B_110:
                    // cfsetispeed(&tty, B110);
                    // cfsetospeed(&tty, B110);
                    tty.c_ispeed = 110;
                    tty.c_ospeed = 110;
                    break;
                case BaudRate::B_134:
                    // cfsetispeed(&tty, B134);
                    // cfsetospeed(&tty, B134);
                    tty.c_ispeed = 134;
                    tty.c_ospeed = 134;
                    break;
                case BaudRate::B_150:
                    // cfsetispeed(&tty, B150);
                    // cfsetospeed(&tty, B150);
                    tty.c_ispeed = 150;
                    tty.c_ospeed = 150;
                    break;
                case BaudRate::B_200:
                    // cfsetispeed(&tty, B200);
                    // cfsetospeed(&tty, B200);
                    tty.c_ispeed = 200;
                    tty.c_ospeed = 200;
                    break;
                case BaudRate::B_300:
                    // cfsetispeed(&tty, B300);
                    // cfsetospeed(&tty, B300);
                    tty.c_ispeed = 300;
                    tty.c_ospeed = 300;
                    break;
                case BaudRate::B_600:
                    // cfsetispeed(&tty, B600);
                    // cfsetospeed(&tty, B600);
                    tty.c_ispeed = 600;
                    tty.c_ospeed = 600;
                    break;
                case BaudRate::B_1200:
                    // cfsetispeed(&tty, B1200);
                    // cfsetospeed(&tty, B1200);
                    tty.c_ispeed = 1200;
                    tty.c_ospeed = 1200;
                    break;
                case BaudRate::B_1800:
                    // cfsetispeed(&tty, B1800);
                    // cfsetospeed(&tty, B1800);
                    tty.c_ispeed = 1800;
                    tty.c_ospeed = 1800;
                    break;
                case BaudRate::B_2400:
                    // cfsetispeed(&tty, B2400);
                    // cfsetospeed(&tty, B2400);
                    tty.c_ispeed = 2400;
                    tty.c_ospeed = 2400;
                    break;
                case BaudRate::B_4800:
                    // cfsetispeed(&tty, B4800);
                    // cfsetospeed(&tty, B4800);
                    tty.c_ispeed = 4800;
                    tty.c_ospeed = 4800;
                    break;
                case BaudRate::B_9600:
                    // cfsetispeed(&tty, B9600);
                    // cfsetospeed(&tty, B9600);
                    tty.c_ispeed = 9600;
                    tty.c_ospeed = 9600;
                    break;
                case BaudRate::B_19200:
                    // cfsetispeed(&tty, B19200);
                    // cfsetospeed(&tty, B19200);
                    tty.c_ispeed = 19200;
                    tty.c_ospeed = 19200;
                    break;
                case BaudRate::B_38400:
                    // cfsetispeed(&tty, B38400);
                    // cfsetospeed(&tty, B38400);
                    tty.c_ispeed = 38400;
                    tty.c_ospeed = 38400;
                    break;
                case BaudRate::B_57600:
                    // cfsetispeed(&tty, B57600);
                    // cfsetospeed(&tty, B57600);
                    tty.c_ispeed = 57600;
                    tty.c_ospeed = 57600;
                    break;
                case BaudRate::B_115200:
                    // cfsetispeed(&tty, B115200);
                    // cfsetospeed(&tty, B115200);
                    tty.c_ispeed = 115200;
                    tty.c_ospeed = 115200;
                    break;
                case BaudRate::B_230400:
                    // cfsetispeed(&tty, B230400);
                    // cfsetospeed(&tty, B230400);
                    tty.c_ispeed = 230400;
                    tty.c_ospeed = 230400;
                    break;
                case BaudRate::B_460800:
                    // cfsetispeed(&tty, B460800);
                    // cfsetospeed(&tty, B460800);
                    tty.c_ispeed = 460800;
                    tty.c_ospeed = 460800;
                    break;
                default:
                    throw std::runtime_error(std::string() + "baudRate passed to " + __PRETTY_FUNCTION__ + " unrecognized.");
            }
        }
        // This does no different than STANDARD atm, but let's keep
        // them separate for now....
        else if (baudRateType_ == BaudRateType::CUSTOM)
        {
            tty.c_cflag &= ~CBAUD;
            tty.c_cflag |= CBAUDEX;
            // tty.c_cflag |= BOTHER;
            tty.c_ispeed = baudRateCustom_;
            tty.c_ospeed = baudRateCustom_;


            // #include <linux/serial.h>
            // // configure port to use custom speed instead of 38400
            // struct serial_struct ss;
            // ioctl(fileDesc_, TIOCGSERIAL, &ss);
            // ss.flags = (ss.flags & ~ASYNC_SPD_MASK) | ASYNC_SPD_CUST;
            // ss.custom_divisor = (ss.baud_base + (baudRateCustom_ / 2)) / baudRateCustom_;
            // int closestSpeed = ss.baud_base / ss.custom_divisor;

            // if (closestSpeed < baudRateCustom_ * 98 / 100 || closestSpeed > baudRateCustom_ * 102 / 100) {
            // 	printf("Cannot set serial port speed to %d. Closest possible is %d\n", baudRateCustom_, closestSpeed);
            // }

            // ioctl(fileDesc_, TIOCSSERIAL, &ss);

            // cfsetispeed(&tty, B38400);
            // cfsetospeed(&tty, B38400);
        }
        else
        {
            // Should never get here, bug in this libraries code!
            assert(false);
        }

        //===================== (.c_oflag) =================//

        tty.c_oflag     =   0;              // No remapping, no delays
        tty.c_oflag     &=  ~OPOST;         // Make raw

        //================= CONTROL CHARACTERS (.c_cc[]) ==================//

        // c_cc[VTIME] sets the inter-character timer, in units of 0.1s.
        // Only meaningful when port is set to non-canonical mode
        // VMIN = 0, VTIME = 0: No blocking, return immediately with what is available
        // VMIN > 0, VTIME = 0: read() waits for VMIN bytes, could block indefinitely
        // VMIN = 0, VTIME > 0: Block until any amount of data is available, OR timeout occurs
        // VMIN > 0, VTIME > 0: Block until either VMIN characters have been received, or VTIME
        //                      after first character has elapsed
        // c_cc[WMIN] sets the number of characters to block (wait) for when read() is called.
        // Set to 0 if you don't want read to block. Only meaningful when port set to non-canonical mode

        if(timeout_ms_ == -1) {
            // Always wait for at least one byte, this could
            // block indefinitely
            tty.c_cc[VTIME] = 0;
            tty.c_cc[VMIN] = 1;
        } else if(timeout_ms_ == 0) {
            // Setting both to 0 will give a non-blocking read
            tty.c_cc[VTIME] = 0;
            tty.c_cc[VMIN] = 0;
        } else if(timeout_ms_ > 0) {
            tty.c_cc[VTIME] = (cc_t)(timeout_ms_/100);    // 0.5 seconds read timeout
            tty.c_cc[VMIN] = 0;
        }

        //======================== (.c_iflag) ====================//

        switch(softwareFlowControl_){
            case SoftwareFlowControl::OFF:
                tty.c_iflag &= ~(IXON | IXOFF | IXANY);
            break;

            case SoftwareFlowControl::ON:
                tty.c_iflag |= (IXON | IXOFF | IXANY);
            break;
        }
        
        tty.c_iflag 	&= ~(IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR|IGNCR|ICRNL);

        //=========================== LOCAL MODES (c_lflag) =======================//

        // Canonical input is when read waits for EOL or EOF characters before returning. In non-canonical mode, the rate at which
        // read() returns is instead controlled by c_cc[VMIN] and c_cc[VTIME]
        tty.c_lflag		&= ~ICANON;    // Turn off canonical input, which is suitable for pass-through
        // Configure echo depending on echo_ boolean
        if(echo_) {
            tty.c_lflag |= ECHO;
        } else {
            tty.c_lflag &= ~(ECHO);
        }
        tty.c_lflag		&= ~ECHOE;     // Turn off echo erase (echo erase only relevant if canonical input is active)
        tty.c_lflag		&= ~ECHONL;    //
        tty.c_lflag		&= ~ISIG;      // Disables recognition of INTR (interrupt), QUIT and SUSP (suspend) characters


        // Try and use raw function call
        //cfmakeraw(&tty);

        // this->SetTermios(tty);
        this->SetTermios2(tty);

        /*
        // Flush port, then apply attributes
        tcflush(this->fileDesc, TCIFLUSH);

        if(tcsetattr(this->fileDesc, TCSANOW, &tty) != 0)
        {
            // Error occurred
            this->sp->PrintError(SmartPrint::Ss() << "Could not apply terminal attributes for \"" << this->filePath << "\" - " << strerror(errno));
            return;
        }*/
    }

    void SerialPort::Write(const std::string& data) {
        PortIsOpened(__PRETTY_FUNCTION__);

        int writeResult = write(fileDesc_, data.c_str(), data.size());

        // Check status
        if (writeResult == -1) {
            throw std::system_error(EFAULT, std::system_category());
        }
    }

    void SerialPort::WriteBinary(const std::vector<uint8_t>& data) {
        PortIsOpened(__PRETTY_FUNCTION__);

        int writeResult = write(fileDesc_, data.data(), data.size());

        // Check status
        if (writeResult == -1) {
            throw std::system_error(EFAULT, std::system_category());
        }
    }

    void SerialPort::Read(std::string& data) {
        PortIsOpened(__PRETTY_FUNCTION__);

        // Read from file
        // We provide the underlying raw array from the readBuffer_ vector to this C api.
        // This will work because we do not delete/resize the vector while this method
        // is called
        ssize_t n = read(fileDesc_, &readBuffer_[0], readBufferSize_B_);

        // Error Handling
        if(n < 0) {
            // Read was unsuccessful
            throw std::system_error(EFAULT, std::system_category());
        }
        else if(n == 0) {
            // n == 0 means EOS, but also returned on device disconnection. We try to get termios2 to distinguish two these two states
            struct termios2 term2;
            int rv = ioctl(fileDesc_, TCGETS2, &term2);

            if(rv != 0) {
                throw std::system_error(EFAULT, std::system_category());
            }
        }
        else if(n > 0) {
            data += std::string(&readBuffer_[0], n);
        }

        // If code reaches here, read must of been successful
    }

    void SerialPort::ReadBinary(std::vector<uint8_t>& data) {
        PortIsOpened(__PRETTY_FUNCTION__);

        // Read from file
        // We provide the underlying raw array from the readBuffer_ vector to this C api.
        // This will work because we do not delete/resize the vector while this method
        // is called
        ssize_t n = read(fileDesc_, &readBuffer_[0], readBufferSize_B_);

        // Error Handling
        if(n < 0) {
            // Read was unsuccessful
            throw std::system_error(EFAULT, std::system_category());
        } else if(n == 0) {
            // n == 0 means EOS, but also returned on device disconnection. We try to get termios2 to distinguish two these two states
            struct termios2 term2;
            int rv = ioctl(fileDesc_, TCGETS2, &term2);

            if(rv != 0) {
                throw std::system_error(EFAULT, std::system_category());
            }
        } else if(n > 0) {
            std::copy(readBuffer_.begin(), readBuffer_.begin() + n, back_inserter(data));
        }

        // If code reaches here, read must of been successful
    }

    // termios SerialPort::GetTermios() {
    //     if(fileDesc_ == -1)
    //         throw std::runtime_error("GetTermios() called but file descriptor was not valid.");

    // 	struct termios tty;
    // 	memset(&tty, 0, sizeof(tty));

    // 	// Get current settings (will be stored in termios structure)
    // 	if(tcgetattr(fileDesc_, &tty) != 0)
    // 	{
    // 		// Error occurred
    // 		std::cout << "Could not get terminal attributes for \"" << device_ << "\" - " << strerror(errno) << std::endl;
    // 		throw std::system_error(EFAULT, std::system_category());
    // 		//return false;
    // 	}

    // 	return tty;
    // }

    // void SerialPort::SetTermios(termios myTermios)
    // {
    // 	// Flush port, then apply attributes
    // 	tcflush(fileDesc_, TCIFLUSH);

    // 	if(tcsetattr(fileDesc_, TCSANOW, &myTermios) != 0)
    // 	{
    // 		// Error occurred
    // 		std::cout << "Could not apply terminal attributes for \"" << device_ << "\" - " << strerror(errno) << std::endl;
    // 		throw std::system_error(EFAULT, std::system_category());

    // 	}

    // 	// Successful!
    // }

    termios2 SerialPort::GetTermios2()
    {
        struct termios2 term2;

        ioctl(fileDesc_, TCGETS2, &term2);

        return term2;

        // term2.c_cflag &= ~CBAUD;  /* Remove current BAUD rate */
        // term2.c_cflag |= BOTHER;  /* Allow custom BAUD rate using int input */
        // term2.c_ispeed = speed;   /* Set the input BAUD rate */
        // term2.c_ospeed = speed;   /* Set the output BAUD rate */

        // ioctl(fd, TCSETS2, &term2);
    }

    void SerialPort::SetTermios2(termios2 tty)
    {
        ioctl(fileDesc_, TCSETS2, &tty);
    }

    void SerialPort::PortIsOpened(const std::string& prettyFunc) {

        if(state_ != State::OPEN) {
            THROW_EXCEPT(std::string() + prettyFunc + " called but state != OPEN. Please call Open() first.");
        }

        if(fileDesc_ < 0) {
            THROW_EXCEPT(std::string() + prettyFunc + " called but file descriptor < 0, indicating file has not been opened.");
        }
    }

    void SerialPort::Close() {
        if(fileDesc_ != -1) {
            auto retVal = close(fileDesc_);
            if(retVal != 0)
                THROW_EXCEPT("Tried to close serial port " + device_ + ", but close() failed.");

            fileDesc_ = -1;
        }

        state_ = State::CLOSED;
    }

    void SerialPort::SetTimeout(int32_t timeout_ms) {
        if(timeout_ms < -1)
            THROW_EXCEPT(std::string() + "timeout_ms provided to " + __PRETTY_FUNCTION__ + " was < -1, which is invalid.");
        if(timeout_ms > 25500)
            THROW_EXCEPT(std::string() + "timeout_ms provided to " + __PRETTY_FUNCTION__ + " was > 25500, which is invalid.");
        if(state_ == State::OPEN)
            THROW_EXCEPT(std::string() + __PRETTY_FUNCTION__ + " called while state == OPEN.");
        timeout_ms_ = timeout_ms;
    }
    
    int32_t SerialPort::Available() {
        PortIsOpened(__PRETTY_FUNCTION__);

        int32_t ret = 0;
        ioctl(fileDesc_, FIONREAD, &ret);
        return ret;
        
    }
    State SerialPort::GetState() {
      return state_;
    }

} // namespace CppLinuxSerial
} // namespace mn