trigger.c

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#include "select.h"
#include "ndelay.h"
#include "open.h"
#include "trigger.h"
#include "close.h"
 
static int fd = -1;
 
void trigger_set(void) 
{
  if (fd != -1) close(fd);
  fd = open_read("lock/trigger");
}
 
void trigger_selprep(int *nfds,fd_set *rfds) 
{
  if (fd != -1) {
    FD_SET(fd,rfds);
    if (*nfds < fd + 1) *nfds = fd + 1;
  }
}
 
int trigger_pulled(fd_set *rfds) 
{
  if (fd != -1) if (FD_ISSET(fd,rfds)) return 1;
  return 0;
}
 
void write(int,char *,int);
 
void triggerpull(void) 
{
  int fd;
 
  fd = open_write("lock/trigger");
  if (fd >= 0) {
    ndelay_on(fd);
    write(fd,"",1); /* if it fails, bummer */
    close(fd);
  }
}