diff options
Diffstat (limited to 'flow-native/src/platform/posix/flow.c')
| -rw-r--r-- | flow-native/src/platform/posix/flow.c | 247 |
1 files changed, 247 insertions, 0 deletions
diff --git a/flow-native/src/platform/posix/flow.c b/flow-native/src/platform/posix/flow.c new file mode 100644 index 0000000..a2a239c --- /dev/null +++ b/flow-native/src/platform/posix/flow.c @@ -0,0 +1,247 @@ +#include <stdlib.h> +#include <stdio.h> +#include <unistd.h> +#include <errno.h> +#include <termios.h> +#include <fcntl.h> +#include <sys/file.h> +#include "flow.h" + + +#define DATA_CANCEL 0xffffffff + +static bool debug = false; +#define DEBUG(f) if (debug) {f} + +void serial_debug(bool value) { + debug = value; +} + +//contains file descriptors used in managing a serial port +struct serial_config { + int port_fd; // file descriptor of serial port + + /* a pipe is used to abort a serial read by writing something into the + * write end of the pipe */ + int pipe_read_fd; // file descriptor, read end of pipe + int pipe_write_fd; // file descriptor, write end of pipe +}; + +int serial_open( + const char* const port_name, + int baud, + int char_size, + bool two_stop_bits, + int parity, + struct serial_config** serial) { + + int fd = open(port_name, O_RDWR | O_NOCTTY | O_NONBLOCK); + + if (fd < 0) { + int en = errno; + DEBUG(perror("error obtaining port file descriptor");); + if (en == EACCES) return E_ACCESS_DENIED; + if (en == ENOENT) return E_NO_PORT; + return E_IO; + } + + if (flock(fd, LOCK_EX | LOCK_NB) < 0) { + DEBUG(perror("error acquiring lock on port");); + close(fd); + return E_BUSY; + } + + /* configure new port settings */ + struct termios newtio; + + /* initialize serial interface */ + newtio.c_iflag = 0; + newtio.c_oflag = 0; + newtio.c_lflag = 0; + newtio.c_cflag = CREAD; + + /* set speed */ + speed_t bd; + switch (baud) { + case 50: bd = B50; break; + case 75: bd = B75; break; + case 110: bd = B110; break; + case 134: bd = B134; break; + case 150: bd = B150; break; + case 200: bd = B200; break; + case 300: bd = B300; break; + case 600: bd = B600; break; + case 1200: bd = B1200; break; + case 1800: bd = B1800; break; + case 2400: bd = B2400; break; + case 4800: bd = B4800; break; + case 9600: bd = B9600; break; + case 19200: bd = B19200; break; + case 38400: bd = B38400; break; + case 57600: bd = B57600; break; + case 115200: bd = B115200; break; + case 230400: bd = B230400; break; + default: + close(fd); + DEBUG(fprintf(stderr, "invalid baud rate %d\n", baud);); + return E_INVALID_SETTINGS; + } + + if (cfsetspeed(&newtio, bd) < 0) { + DEBUG(perror("error setting baud rate");); + close(fd); + return E_IO; + } + + /* set char size*/ + switch (char_size) { + case 5: newtio.c_cflag |= CS5; break; + case 6: newtio.c_cflag |= CS6; break; + case 7: newtio.c_cflag |= CS7; break; + case 8: newtio.c_cflag |= CS8; break; + default: + close(fd); + DEBUG(fprintf(stderr, "invalid character size %d\n", char_size);); + return E_INVALID_SETTINGS; + } + + /* use two stop bits */ + if (two_stop_bits){ + newtio.c_cflag |= CSTOPB; + } + + /* set parity */ + switch (parity) { + case PARITY_NONE: break; + case PARITY_ODD: newtio.c_cflag |= (PARENB | PARODD); break; + case PARITY_EVEN: newtio.c_cflag |= PARENB; break; + default: + close(fd); + DEBUG(fprintf(stderr, "invalid parity %d\n", parity);); + return E_INVALID_SETTINGS; + } + + if (tcflush(fd, TCIOFLUSH) < 0) { + DEBUG(perror("error flushing serial settings");); + close(fd); + return E_IO; + } + + if (tcsetattr(fd, TCSANOW, &newtio) < 0) { + DEBUG(perror("error applying serial settings");); + close(fd); + return E_IO; + } + + int pipe_fd[2]; + if (pipe(pipe_fd) < 0) { + DEBUG(perror("error opening pipe");); + close(fd); + return E_IO; + } + + if (fcntl(pipe_fd[0], F_SETFL, O_NONBLOCK) < 0 || fcntl(pipe_fd[1], F_SETFL, O_NONBLOCK) < 0) { + DEBUG(perror("error setting pipe to non-blocking");); + close(fd); + close(pipe_fd[0]); + close(pipe_fd[1]); + return E_IO; + } + + struct serial_config* s = malloc(sizeof(s)); + if (s == NULL) { + DEBUG(perror("error allocating memory for serial configuration");); + close(fd); + close(pipe_fd[0]); + close(pipe_fd[1]); + return E_IO; + } + + s->port_fd = fd; + s->pipe_read_fd = pipe_fd[0]; + s->pipe_write_fd = pipe_fd[1]; + (*serial) = s; + + return 0; +} + + +int serial_close(struct serial_config* const serial) { + if (close(serial->pipe_write_fd) < 0) { + DEBUG(perror("error closing write end of pipe");); + return E_IO; + } + if (close(serial->pipe_read_fd) < 0) { + DEBUG(perror("error closing read end of pipe");); + return E_IO; + } + + if (flock(serial->port_fd, LOCK_UN) < 0){ + DEBUG(perror("error releasing lock on port");); + return E_IO; + } + if (close(serial->port_fd) < 0) { + DEBUG(perror("error closing port");); + return E_IO; + } + + free(serial); + return 0; +} + +int serial_read(struct serial_config* const serial, char* const buffer, size_t size) { + int port = serial->port_fd; + int pipe = serial->pipe_read_fd; + + fd_set rfds; + FD_ZERO(&rfds); + FD_SET(port, &rfds); + FD_SET(pipe, &rfds); + + int nfds = pipe + 1; + if (pipe < port) nfds = port + 1; + + int n = select(nfds, &rfds, NULL, NULL, NULL); + if (n < 0) { + DEBUG(perror("error trying to call select on port and pipe");); + return E_IO; + } + + if (FD_ISSET(pipe, &rfds)) { + return E_INTERRUPT; + } else if (FD_ISSET(port, &rfds)) { + int r = read(port, buffer, size); + + //treat 0 bytes read as an error to avoid problems on disconnect + //anyway, after a poll there should be more than 0 bytes available to read + if (r <= 0) { + DEBUG(perror("error data not available after select");); + return E_IO; + } + return r; + } else { + fprintf(stderr, "select returned unknown read sets\n"); + return E_IO; + } +} + +int serial_cancel_read(struct serial_config* const serial) { + int data = DATA_CANCEL; + + //write to pipe to wake up any blocked read thread (self-pipe trick) + if (write(serial->pipe_write_fd, &data, 1) < 0) { + DEBUG(perror("error writing to pipe during read cancel");); + return E_IO; + } + + return 0; +} + +int serial_write(struct serial_config* const serial, char* const data, size_t size) { + int r = write(serial->port_fd, data, size); + if (r < 0) { + DEBUG(perror("error writing to port");); + return E_IO; + } + return r; +}
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