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Subject: 
Re: legOS ... really a stack question
Newsgroups: 
lugnet.robotics
Date: 
Sat, 2 Jan 1999 22:44:15 GMT
Viewed: 
1234 times
  
Rick Kimball <kimballr@nh.ultranet.com> wrote:
Then I noticed that in the h8300.rcx file the stack
starts at 0xfefc.  I'm assuming this is the top of
the stack and that it should grow downward towards the
heap which ends at 0xcc00.  Let's just ignore the stack
and the heap colliding for now.

If both of my assumptions above are correct won't the
direct-motor routines stomp the stack.

I changed the topram entry in my h8300.rcx to be 0xef00 instead
of 0xfefc.  This made the program run without any problems.
Was I just lucky or are my assumptions correct?

Looking at my memory map, it appears that there is space for the stack in
on-chip memory between fdc0 and ff7e (or thereabouts).  That's just about
450 bytes.  If you need more stack space than that, you'll need to move the
stack to off-chip memory.  Using ef3c for the first stack element seems to
be a safe place, but ef00 is okay if you want to be really conservative.
Note that off-chip memory is slower than on-chip memory.

By the way, the fefc entry in h8300.rcx appears to be ignored.  It's there
to define the _stack symbol, which is unused.  You mentioned libgcc2.c, but
that does not appear to reference the stack symbol or set the stack
pointer.  What gives?

I do not link to any GNU libraries, I do not use C++, I do not use
h8300.rcx.  I have written everything from scratch.  But I have looked at
h8300.rcx.

I'm curious what your setup is.  Mine is certainly different from yours.

-Kekoa



Message is in Reply To:
  legOS ... really a stack question
 
I'm still having reliability problems with legOS when using the task management routines. However, I think the problem has more to do with the stack than the tm routines. I think the problem is related to the direct-motor routines and the entries in (...) (25 years ago, 2-Jan-99, to lugnet.robotics)

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