PPS的简单使用

参考例子：QNX® Software Development Platform 6.6 http://www.qnx.com/developers/docs/6.6.0_anm11_wf10/#com.qnx.doc.pps.developer/topic/examples.html 

//subscriber/main.cpp
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>

int main(int argc, char *argv[])
{
   int fd;
   char buf[256];
   int num_bytes;

   fd = open( "/pps/button?wait,delta", O_RDONLY );
   if ( fd < 0 )
   {
      perror ("Couldn't open /pps/button");
      return EXIT_FAILURE;
   }

   /* Loop, echoing the attributes of the button. */
   while (1)
   {
      num_bytes = read( fd, buf, sizeof(buf) );
      if (num_bytes > 0)
      {
        write (STDOUT_FILENO, buf, num_bytes);
      }
   }

   return EXIT_SUCCESS;
}

//publish/main.cpp
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>

int main(int argc, char *argv[])
{
   int fd;
   int state = 0;
   char buf[256];
   struct stat stat_buf;
   int count = 0;
   ssize_t len, bytes_written;

   /* Is PPS running? */
   if (stat( "/pps", &stat_buf) != 0)
   {
      if (errno == ENOENT)
         printf ("The PPS server isn't running.\n");
      else
         perror ("stat (/pps)");
      return EXIT_FAILURE;
   }

   /* Create the "button" object (if it doesn't already exist). */
   fd = open( "/pps/button", O_RDWR | O_CREAT, S_IRWXU | S_IRWXG | S_IRWXO );
   if ( fd < 0 )
   {
      perror ("Couldn't open /pps/button");
      return EXIT_FAILURE;
   }

   /* Loop forever, toggling the state of the button. */
   while ( 1 )
   {
      usleep (500);
      count++;
      len = snprintf(buf, 256, "state::%s\npub1::%d", state ? "on" : "off", count);
      bytes_written = write( fd, buf, len );
      if (bytes_written == -1)
      {
         perror ("write()");
      }
      else if (bytes_written != len)
      {
         printf ("Bytes written: %d String length: %d\n", bytes_written, len);
      }

      if ( state == 0 )
         state = 1;
      else
         state = 0;
   }

   return EXIT_SUCCESS;
}

标签：int,简单,bytes,PPS,state,fd,使用,include,buf
来源： https://blog.csdn.net/m0_37844072/article/details/121996347