Cell 3
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Function Reference
| # |
Function |
Parameters |
Description |
Return Value |
| 0 |
int open(const char *pathname, int flags, ...) |
pathname: Path (e.g., "COM3")
flags: POSIX flags (e.g., O_RDWR) |
Opens a file or serial port, assigns FD. |
FD or -1 (sets errno) |
| 1 |
int close(int fd) |
fd: File descriptor |
Closes an open FD. |
0 or -1 (sets errno) |
| 2 |
static HANDLE _get_handle(int fd) |
fd: File descriptor |
Internal: Gets HANDLE from FD. |
HANDLE or INVALID_HANDLE_VALUE |
| 3 |
int tcgetattr(int fd, struct termios *termios_p) |
fd: FD
termios_p: termios ptr |
Gets terminal attributes. |
0 or -1 |
| 4 |
int tcsetattr(int fd, int optional_actions, const struct termios *termios_p) |
fd: FD
optional_actions: TCSANOW, etc.
termios_p: termios ptr |
Sets terminal attributes. |
0 or -1 |
| 5 |
int tcsendbreak(int fd, int duration) |
fd: Serial FD
duration: Break time (ms) |
Sends a break signal on serial port. |
0 or -1 |
| 6 |
int tcdrain(int fd) |
fd: FD |
Waits for output to drain. |
0 or -1 |
| 7 |
int tcflush(int fd, int queue_selector) |
fd: FD
queue_selector: TCIFLUSH, etc. |
Flushes queues. |
0 or -1 |
| 8 |
int tcflow(int fd, int action) |
fd: Serial FD
action: TCOOFF, etc. |
Controls serial flow. |
0 or -1 |
| 9 |
speed_t cfgetispeed(const struct termios *termios_p) |
termios_p: termios ptr |
Gets input baud rate. |
Baud rate |
| 10 |
speed_t cfgetospeed(const struct termios *termios_p) |
termios_p: termios ptr |
Gets output baud rate. |
Baud rate |
| 11 |
int cfsetispeed(struct termios *termios_p, speed_t speed) |
termios_p: termios ptr
speed: Baud rate |
Sets input baud rate. |
0 |
| 12 |
int cfsetospeed(struct termios *termios_p, speed_t speed) |
termios_p: termios ptr
speed: Baud rate |
Sets output baud rate. |
0 |
| 13 |
int cfsetspeed(struct termios *termios_p, speed_t speed) |
termios_p: termios ptr
speed: Baud rate |
Sets both baud rates. |
0 |
| 14 |
pid_t tcgetsid(int fd) |
fd: FD |
Gets session ID (process ID on Windows). |
Process ID |
| 15 |
int _kbhit(void) |
None |
Non-Blocking: Checks for console keypress. |
1 if key available, 0 otherwise |
| 16 |
int GetC(void) |
None |
Non-Blocking: Gets printable char or -1. |
ASCII value or -1 |
Note: Non-blocking functions _kbhit() and GetC() are highlighted in yellow.
Example Usage
int main(void) {
struct termios tty;
char c;
int fd = open("COM3", O_RDWR);
if (fd >= 0) {
tcgetattr(fd, &tty);
cfsetispeed(&tty, B9600);
cfsetospeed(&tty, B9600);
cfsetspeed(&tty, B9600);
tty.c_cflag |= CS8 | CREAD;
tcsetattr(fd, TCSANOW, &tty);
printf("Speeds: %u, %u\n", cfgetispeed(&tty), cfgetospeed(&tty));
tcsendbreak(fd, 500);
tcflush(fd, TCOFLUSH);
tcflow(fd, TCOON);
tcdrain(fd);
close(fd);
}
tcgetattr(0, &tty);
tty.c_lflag &= ~ISIG;
tty.c_cc[VEOF] = _POSIX_VDISABLE;
tty.c_cc[VERASE] = _POSIX_VDISABLE;
tcsetattr(0, TCSANOW, &tty);
printf("Session ID: %lld\n", (long long)tcgetsid(0));
printf("Press 'q' to quit...\n");
for (;;) {
if (_kbhit()) {
if ((c = GetC()) == 'q') break;
if (c != -1) printf("Key: %c (%d)\n", c, c);
}
Sleep(100);
}
fd = open("test.txt", O_RDWR | O_CREAT | O_TRUNC);
if (fd >= 0) {
WriteFile(_get_handle(fd), "Hello\n", 6, NULL, NULL);
close(fd);
}
printf("Exiting...\n");
return 0;
}
Download wtermio.c Source File
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Cell 5
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