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Subject: 
Re: Stack Overflow
Newsgroups: 
lugnet.robotics.handyboard
Date: 
Sun, 24 Jan 1999 13:53:49 GMT
Original-From: 
Fred G. Martin <fredm@media.mitNOMORESPAM.edu>
Viewed: 
1219 times
  
IC is implemented using lex and yacc (tools originally on unix systems
for building parsers and compilers, which generate C code that be
compiled into apps on many platforms).

as someone pointed out, if yacc barfs, it's because you've got an
expression that is too heavily nested and thus requires too much stack
to parse.  so yes, it's a compile-time stack issue, having nothing to
do with IC process stack space.

i don't know if the commercial IC will do any better.  it depends if
more stack is allocated to yacc.  randy could answer this.

i think you already know your answer---break up your program into
smaller chunks.

fred


William Sitch wrote:

Hi everyone:

    I'm trying to download a rather large chunk of code to the HandyBoard,
and I'm having a problem when I exceed a certain number of instructions in a
procedure I'm running.  When I try to download the code, I get the error
"yacc stack overflow" pointing to a line in a procedure that I spawn to be
multitasked.

I tried to increase the stack size of the process I spawn, but the error
still exists.  I think I might be getting a compile-time stack overflow - or
something like that.  The procedure it crashes for is a leg controller, and
consists of many "if .. else if" statements.

It would be bad design to move some of the code to another procedure, and I
would like to avoid doing that.  Does anyone know exactly why I'm having
this problem, or what I could do to remedy the situation?

Thanks in advance.

--
William Sitch
4th Year Electrical Engineering   http://www.engsoc.carleton.ca/~wsitch

I'm pretty good at software and may be able to help you.  But I need to see you
r
code: please send it to me privately and I'll see what I can do.

PS:  What kind of hardware/software platform are you on?  "Yacc" is typically a
Unix program that I thought had nothing to do with IC.  (And yes, the real Unix
"yacc" can stack overflow with excessively nested if/then/else quite easily...
I just fixed a problem like that for my employer).

/Max



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