pulse_attach()

Attach a handler function to a pulse code

Synopsis:

#include <sys/iofunc.h>
#include <sys/dispatch.h>

int pulse_attach( dispatch_t * dpp,
                  int flags,
                  int code,
                  int (* func)
                      ( message_context_t * ctp,
                        int code,
                        unsigned flags,
                        void * handle ),
                  void * handle );

Arguments:

dpp

The dispatch handle, as returned by dispatch_create().

flags

Currently, the following flag is defined in <sys/dispatch.h>:

• MSG_FLAG_ALLOC_PULSE — allocate and attach a pulse code that's different than any other code that was either given to pulse_attach() through the code argument, or allocated by pulse_attach(). The allocated code is in the range _PULSE_CODE_MINAVAIL and _PULSE_CODE_MAXAVAIL.

code

The pulse code that you want to attach the function to.

func

The function that you want to call when a message in the given range is received; see below, as well as “Handler function” in the documentation for message_attach().

handle

An arbitrary handle that you want to associate with data for the defined message range. This handle is passed to func.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The pulse_attach() function attaches a pulse code to a user-supplied function func. You can use the same function func with message_attach(). By examining ctp->rcvid, the func function can determine whether a pulse or message was received.

When the resource manager receives a pulse that matches code, it calls func. This user-supplied function is responsible for doing any specific work needed to handle the pulse pointed to by ctp->msg.pulse. The handle passed to the function is the handle initially passed to pulse_attach(). The handle may be a device entry you want associated with the pulse code. Your function should return 0; other return values are reserved.

You typically use pulse_attach() to associate pulses generated by interrupt handlers or timers with a routine in the main program of your resource manager.

Returns:

If MSG_FLAG_ALLOC_PULSE is specified, the function returns the allocated pulse code; otherwise, it returns the code that's passed in. On failure, -1 is returned (errno is set).

Errors:

EAGAIN

Couldn't allocate a pulse code.

EINVAL

The pulse code is out of range, or it's already registered.

ENOMEM

Insufficient memory to allocate internal data structures.

Examples:

#include <sys/dispatch.h>
#include <time.h>
#include <stdio.h>    
#include <stdlib.h>
        
int my_func( … ) {

   …

}
        
int main( int argc, char **argv ) {
   dispatch_t    *dpp;
   int           flag = 0, code, mycode;
    
   if ( ( dpp = dispatch_create() ) == NULL ) {
      fprintf( stderr, "%s: Unable to allocate \
               dispatch handle.\n",argv[0] );
      return EXIT_FAILURE;
   }

   …

   mycode = …;

   if ( (code = pulse_attach( dpp, flag, mycode,
                &my_func, NULL)) == -1 ) {
      fprintf ( stderr, "Failed to attach code %d.\n", mycode );
      return 1;
   }
   /* else successfully attached a pulse code */
            
   …
}

For examples using the dispatch interface, see dispatch_create(), message_attach(), resmgr_attach(), and thread_pool_create().

Classification:

QNX Neutrino

See also:

message_attach(), pulse_detach()

“Layers in a resource manager” in the Bones of a Resource Manager chapter of Writing a Resource Manager