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stevech



Joined: 23 Feb 2006
Posts: 656
Posted: 20 September 2006, 5:37 AM    Post subject: TCB links Reply with quote
Don

If you would, please point out my error in this code which attempts to walk the list of active tasks. It prints out poo-poo in an infinite loop. I assume that the list ends with a null pointer.

Code:
sub showTaskList()
   dim p1 as unsignedinteger, p2 as unsignedinteger
   
   p1 = register.TaskMain  ' TCB address
   
   Do
      debug.print cStrHex(p1);" ";
      p1 = ramPeekWord(p1+3)
   loop while p1<>0
   debug.print
end sub


EDIT update: looks like end of list is not a zero but rather a pointer to the head of the list. So I found the answer. Now to figure a way to print a task name (sub name). I guess that's up to my own devices.

Code:
sub showTaskList()
   dim p1 as unsignedinteger, p2 as unsignedinteger

   p1 = register.TaskMain
   p2 = p1
   Do
      debug.print cStrHex(p1);" ";
      p1 = ramPeekWord(p1+3)
   loop while (p1 <> p2)
   debug.print
end sub


Last edited by stevech on 20 September 2006, 6:04 AM; edited 1 time in total
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dkinzer
Site Admin


Joined: 03 Sep 2005
Posts: 2493
Location: Portland, OR
Posted: 20 September 2006, 6:01 AM    Post subject: Re: TCB links Reply with quote
stevech wrote:
looks like end of list is not a zero but rather a pointer to the head of the list.

Yes, that is the way that it is documented. The task list is a circular linked list. The application note AN-209 contains similar code that displays the status of all existing tasks. Basically, you have to record where you started and iterate until you return to that spot.
Code:
sub showTaskList()
   dim p1 as unsignedinteger, p2 as unsignedinteger
   
   p1 = register.TaskMain  ' TCB address
   
   Do
      debug.print cStrHex(p1);" ";
      p1 = ramPeekWord(p1+3)
   loop while p1<>register.TaskMain
   debug.print
end sub
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stevech



Joined: 23 Feb 2006
Posts: 656
Posted: 20 September 2006, 6:05 AM    Post subject: Reply with quote
Ah, thanks.
I updated the top of this thread.
I'll go read that AN.

read before leaping, I must remind myself!
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