Lpc2000

Joel Winarske <joelw@...> schrieb am Wed, 30 Nov 2005 
02:14:46 -0800:

>> Any general hints about the cause of such an exception, except the
>> PC somehow gone to the woods, are appreciated...
>
> I seem to recall seeing when porting some AVR code.  It was calling a
> function via pointer that was defined as NULL.
>
> I'm curious what else triggers this.

A simple stack corruption.

void d(void);

void func(void)
{
	int a[2];
	d();			/* forces pushing of LR */
	a[2] = 0;
}

compile with:
arm-thumb-elf-gcc -fomit-frame-pointer -S -mthumb
you get:
         .code   16
         .file   "t.c"
         .text
         .align  2
         .global f
         .code 16
         .thumb_func
         .type   f, %function
f:
         push    {lr}
         sub     sp, sp, #8
         bl      d
         mov     r2, sp
         mov     r3, #0
         str     r3, [r2, #8]
//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

         add     sp, sp, #8
         @ sp needed for prologue
         pop     {pc}
         .size   f, .-f
         .ident  "GCC: (GNU) 3.4.4"


Normaly not that obvious coded :-)

-- 
42Bastian Schick