POSIX TTY

comm_posix_tty.cpp

@@ -0,0 +1,112 @@
+// (C) 2024 by Folkert van Heusden
+// Released under MIT license
+
+#include "gen.h"
+
+#include <cstring>
+#include <errno.h>
+#include <fcntl.h>
+#include <string>
+#include <termios.h>
+#include <thread>
+#include <unistd.h>
+#if defined(_WIN32)
+#include <ws2tcpip.h>
+#include <winsock2.h>
+#else
+#include <poll.h>
+#endif
+
+#include "comm_posix_tty.h"
+#include "log.h"
+
+
+comm_posix_tty::comm_posix_tty(const std::string & device, const int bitrate)
+{
+	fd = open(device.c_str(), O_RDWR);
+	if (fd == -1) {
+		DOLOG(warning, false, "com_posix_tty failed to access %s: %s", device.c_str(), strerror(errno));
+		return;  // TODO error handling
+	}
+
+	// from https://stackoverflow.com/questions/6947413/how-to-open-read-and-write-from-serial-port-in-c
+	termios tty { };
+        if (tcgetattr(fd, &tty) == -1) {
+		DOLOG(warning, false, "com_posix_tty tcgetattr failed: %s", strerror(errno));
+		close(fd);
+                return;
+	}
+
+        cfsetospeed(&tty, bitrate);
+        cfsetispeed(&tty, bitrate);
+
+        tty.c_cflag = (tty.c_cflag & ~CSIZE) | CS8;     // 8-bit chars
+        // disable IGNBRK for mismatched speed tests; otherwise receive break
+        // as \000 chars
+        tty.c_iflag &= ~IGNBRK;         // disable break processing
+        tty.c_lflag = 0;                // no signaling chars, no echo,
+                                        // no canonical processing
+        tty.c_oflag = 0;                // no remapping, no delays
+        tty.c_cc[VMIN]  = 0;            // read doesn't block
+        tty.c_cc[VTIME] = 5;            // 0.5 seconds read timeout
+
+        tty.c_iflag &= ~(IXON | IXOFF | IXANY); // shut off xon/xoff ctrl
+
+        tty.c_cflag |= (CLOCAL | CREAD);// ignore modem controls,
+                                        // enable reading
+        tty.c_cflag &= ~(PARENB | PARODD);      // shut off parity
+        tty.c_cflag &= ~CSTOPB;
+        tty.c_cflag &= ~CRTSCTS;
+
+        if (tcsetattr(fd, TCSANOW, &tty) == -1) {
+		DOLOG(warning, false, "com_posix_tty tcsetattr failed: %s", strerror(errno));
+		close(fd);
+		return;
+	}
+}
+
+comm_posix_tty::~comm_posix_tty()
+{
+	close(fd);
+}
+
+bool comm_posix_tty::is_connected()
+{
+	return true;
+}
+
+bool comm_posix_tty::has_data()
+{
+#if defined(_WIN32)
+	WSAPOLLFD fds[] { { fd, POLLIN, 0 } };
+	int rc = WSAPoll(fds, 1, 0);
+#else
+	pollfd    fds[] { { fd, POLLIN, 0 } };
+	int rc = poll(fds, 1, 0);
+#endif
+
+	return rc == 1;
+}
+
+uint8_t comm_posix_tty::get_byte()
+{
+	uint8_t c = 0;
+	read(fd, &c, 1);  // TODO error handling
+
+	return c;
+}
+
+void comm_posix_tty::send_data(const uint8_t *const in, const size_t n)
+{
+	const uint8_t *p   = in;
+	size_t         len = n;
+
+	while(len > 0) {
+		int rc = write(fd, p, len);
+		if (rc <= 0)  // TODO error checking
+			break;
+
+		p   += rc;
+		len -= rc;
+	}
+}

comm_posix_tty.h

@@ -0,0 +1,23 @@
+// (C) 2024 by Folkert van Heusden
+// Released under MIT license
+
+#include "gen.h"
+#include "comm.h"
+
+
+class comm_posix_tty: public comm
+{
+private:
+	int fd { -1 };
+
+public:
+	comm_posix_tty(const std::string & dev, const int bitrate);
+	virtual ~comm_posix_tty();
+
+	bool    is_connected() override;
+
+	bool    has_data() override;
+	uint8_t get_byte() override;
+
+	void    send_data(const uint8_t *const in, const size_t n) override;
+};