Path: chuka.playstation.co.uk!news
From: Jim <jim@micronetics.com>
Newsgroups: scea.yaroze.programming.codewarrior
Subject: Re: System memory
Date: Thu, 07 Aug 1997 10:41:01 +0100
Organization: PlayStation Net Yaroze (SCEE)
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Wayne K. Werner wrote:

> The easiest form of stack checking I can see for the NY is to run your
> program in debug mode, stepping into each routine to the depth desired.  Do
> a register dump to see what the value of the stack pointer is.  It will
> have the address of the next location to be used for the next push.  By
> comparing this with (_end + _heap_size), you should have a fairly good idea
> of what the stack is doing.  You could also insert the above check into a
> function to fprint the value at various points in your code or a macro to
> do an assert type report and abort (enable and disable this with a stack
> check #define).
> This type of check, although not fool proof could prove quite useful.
>

I've not tryed this method but you could always write a macro called
STACK_CHECK 
that would grab the sp and check it against a specific thresh hold.  For
example

#ifdef (DEBUG)
#define STACKTOP	(0x801ffff4L)
#define THRESHHOLD	((STACKTOP) - (4 * 1024))
#define STACK_CHECK \
{							\
static long _stackcheck;				\
__asm__ volatile ("sw $sp, _stackcheck");		\
if (_stackcheck < THREASHHOLD){				\
	printf("stack exceeded limit. $sp = 0x%X\n", _stackcheck); \
	exit(1);					\
}	
#else
#define STACK_CHECK
#endif

Just put

STACK_CHECK;

as the first line in your function.

I've just grabbed this from the ether so I don't expect it to work
without
a bit of faffing around.  But I think the theory is there.

Remember that the stack moves down towards lower memory, also remember
to 
set the threshhold sightly higher that required.  Printf uses a lot of
stack
to do its thing.  so if it is dangerously low printf may fail.


Let me know how you get on with this.

-JiM