FIFO List/Queue

Forum 2005-2010 (read only) Software Development
1

Hello

I've been search, without success, for a FIFO library/class. I've seen topics and code snippets, none of which were quite what I was looking for, or understandable :-/

Can anyone point me to a true and proven FIFO Queue?

I'm looking for a rather simple implementation:

  • to store long unsigned integers
  • Pop (oldest)
  • Push (newest)
  • Count
  • Empty
  • Peek (oldest, without poping)

Cheers!

2

Hi, I've built a simple event system around an "event queue" which is just that: a specialized fifo.

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1279102180

Look for the EventQueue class. It should be similar to what you need (needs to be adapted of course).

HTH

3

Wow! This is outstanding Mromani!

I've been checking your classes out, have run them, and am quite impressed.

They'll do an outstanding job for what I'm looking to do.

I may add a 'peekEvent' method to the events class, which won't actually dequeue the event. But other than that, they pretty well do the job!

Thanks again.

Ron

4

I'm glad you like the code :slight_smile:
I might add a peek method as soon as I have time or I'll include your own if you'll publish it.

5

I'll be glad to share my peek method.

I'm still deep in 'designing' my application for the moment. Once I've coded and tested the method, I'll post it!

Thanx

6

Implementation proposal for peek method.

// read the next-to-be-dequeued event from the queue;
// returns true if successful, false if the
// queue is empty (the parameteres are not touched
// in this case)
boolean EventQueue::peekEvent(int* ev_code, int* ev_param) {
  
  if (numEvents == 0) {
    return false;
  }

  eventQueueTail = (eventQueueTail + 1) % EVQUEUE_SIZE;

  // store event code and event parameter
  // into the user-supplied variables
  *ev_code = eventQueue[eventQueueTail];
  *ev_param = eventParam[eventQueueTail];

  // don't update the number of events in queue
  // since we're only reading the queue head
  //numEvents--;

  return true;
}

HTH