libserialport  unreleased development snapshot
cross-platform library for accessing serial ports
await_events.c

Awaiting events on multiple ports.

#include <libserialport.h>
#include <stdio.h>
#include <stdlib.h>
/* Example of how to wait for events on multiple ports.
*
* This example file is released to the public domain. */
/* Helper function for error handling. */
int check(enum sp_return result);
int main(int argc, char **argv)
{
/* Get the port names from the command line. */
if (argc < 2) {
printf("Usage: %s <port name>...\n", argv[0]);
return -1;
}
int num_ports = argc - 1;
char **port_names = argv + 1;
/* The ports we will use. */
struct sp_port **ports = malloc(num_ports * sizeof(struct sp_port *));
if (!ports)
abort();
/* The set of events we will wait for. */
struct sp_event_set *event_set;
/* Allocate the event set. */
check(sp_new_event_set(&event_set));
/* Open and configure each port, and then add its RX event
* to the event set. */
for (int i = 0; i < num_ports; i++) {
printf("Looking for port %s.\n", port_names[i]);
check(sp_get_port_by_name(port_names[i], &ports[i]));
printf("Opening port.\n");
check(sp_open(ports[i], SP_MODE_READ));
printf("Setting port to 9600 8N1, no flow control.\n");
check(sp_set_baudrate(ports[i], 9600));
check(sp_set_bits(ports[i], 8));
check(sp_set_parity(ports[i], SP_PARITY_NONE));
check(sp_set_stopbits(ports[i], 1));
printf("Adding port RX event to event set.\n");
check(sp_add_port_events(event_set, ports[i], SP_EVENT_RX_READY));
}
/* Now we can call sp_wait() to await any event in the set.
* It will return when an event occurs, or the timeout elapses. */
printf("Waiting up to 5 seconds for RX on any port...\n");
check(sp_wait(event_set, 5000));
/* Iterate over ports to see which have data waiting. */
for (int i = 0; i < num_ports; i++) {
/* Get number of bytes waiting. */
int bytes_waiting = check(sp_input_waiting(ports[i]));
printf("Port %s: %d bytes received.\n",
sp_get_port_name(ports[i]), bytes_waiting);
}
/* Close ports and free resources. */
sp_free_event_set(event_set);
for (int i = 0; i < num_ports; i++) {
check(sp_close(ports[i]));
sp_free_port(ports[i]);
}
return 0;
}
/* Helper function for error handling. */
int check(enum sp_return result)
{
/* For this example we'll just exit on any error by calling abort(). */
char *error_message;
switch (result) {
case SP_ERR_ARG:
printf("Error: Invalid argument.\n");
abort();
error_message = sp_last_error_message();
printf("Error: Failed: %s\n", error_message);
sp_free_error_message(error_message);
abort();
printf("Error: Not supported.\n");
abort();
case SP_ERR_MEM:
printf("Error: Couldn't allocate memory.\n");
abort();
case SP_OK:
default:
return result;
}
}