examples/await_events.c

   1 #include <libserialport.h>
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4
   5 /* Example of how to wait for events on multiple ports.
   6  *
   7  * This example file is released to the public domain. */
   8
   9 /* Helper function for error handling. */
  10 int check(enum sp_return result);
  11
  12 int main(int argc, char **argv)
  13 {
  14         /* Get the port names from the command line. */
  15         if (argc < 2) {
  16                 printf("Usage: %s <port name>...\n", argv[0]);
  17                 return -1;
  18         }
  19         int num_ports = argc - 1;
  20         char **port_names = argv + 1;
  21
  22         /* The ports we will use. */
  23         struct sp_port **ports = malloc(num_ports * sizeof(struct sp_port *));
  24         if (!ports)
  25                 abort();
  26
  27         /* The set of events we will wait for. */
  28         struct sp_event_set *event_set;
  29
  30         /* Allocate the event set. */
  31         check(sp_new_event_set(&event_set));
  32
  33         /* Open and configure each port, and then add its RX event
  34          * to the event set. */
  35         for (int i = 0; i < num_ports; i++) {
  36                 printf("Looking for port %s.\n", port_names[i]);
  37                 check(sp_get_port_by_name(port_names[i], &ports[i]));
  38
  39                 printf("Opening port.\n");
  40                 check(sp_open(ports[i], SP_MODE_READ));
  41
  42                 printf("Setting port to 9600 8N1, no flow control.\n");
  43                 check(sp_set_baudrate(ports[i], 9600));
  44                 check(sp_set_bits(ports[i], 8));
  45                 check(sp_set_parity(ports[i], SP_PARITY_NONE));
  46                 check(sp_set_stopbits(ports[i], 1));
  47                 check(sp_set_flowcontrol(ports[i], SP_FLOWCONTROL_NONE));
  48
  49                 printf("Adding port RX event to event set.\n");
  50                 check(sp_add_port_events(event_set, ports[i], SP_EVENT_RX_READY));
  51         }
  52
  53         /* Now we can call sp_wait() to await any event in the set.
  54          * It will return when an event occurs, or the timeout elapses. */
  55         printf("Waiting up to 5 seconds for RX on any port...\n");
  56         check(sp_wait(event_set, 5000));
  57
  58         /* Iterate over ports to see which have data waiting. */
  59         for (int i = 0; i < num_ports; i++) {
  60                 /* Get number of bytes waiting. */
  61                 int bytes_waiting = check(sp_input_waiting(ports[i]));
  62                 printf("Port %s: %d bytes received.\n",
  63                                 sp_get_port_name(ports[i]), bytes_waiting);
  64         }
  65
  66         /* Close ports and free resources. */
  67         sp_free_event_set(event_set);
  68         for (int i = 0; i < num_ports; i++) {
  69                 check(sp_close(ports[i]));
  70                 sp_free_port(ports[i]);
  71         }
  72
  73         return 0;
  74 }
  75
  76 /* Helper function for error handling. */
  77 int check(enum sp_return result)
  78 {
  79         /* For this example we'll just exit on any error by calling abort(). */
  80         char *error_message;
  81
  82         switch (result) {
  83         case SP_ERR_ARG:
  84                 printf("Error: Invalid argument.\n");
  85                 abort();
  86         case SP_ERR_FAIL:
  87                 error_message = sp_last_error_message();
  88                 printf("Error: Failed: %s\n", error_message);
  89                 sp_free_error_message(error_message);
  90                 abort();
  91         case SP_ERR_SUPP:
  92                 printf("Error: Not supported.\n");
  93                 abort();
  94         case SP_ERR_MEM:
  95                 printf("Error: Couldn't allocate memory.\n");
  96                 abort();
  97         case SP_OK:
  98         default:
  99                 return result;
 100         }
 101 }