Lpc2000

---- Original Message ----
From: "soren_t_hansen" <soren_t_hansen@...>
To: <lpc2000@yahoogroups.com>
Sent: Saturday, December 31, 2005 2:33 PM
Subject: [lpc2000] Re: Divide by zero

> --- In lpc2000@yahoogroups.com, "Karl Olsen" <kro@p...> wrote:
>>
>> ---- Original Message ----
>> From: "soren_t_hansen" <soren_t_hansen@y...>
>> To: <lpc2000@yahoogroups.com>
>> Sent: Saturday, December 31, 2005 12:12 PM
>> Subject: [lpc2000] Divide by zero
>>
>>> What happenes if you make a division by zero on the LPC2132? I
>>> suspect that you enter the Undefined Instruction exception handler,
>>> but is that correct? I haven't been able to find anything about it
>>> in the manual.
>>
>> No, the ARM7TDMI does not have a hardware divide instruction, so
>> divisions are purely a software matter.
>>
>> With gcc, the compiler calls __divsi3 and __udivsi3 for signed and
>> unsigned integer divisions, and they are implemented in libgcc, a
>> part of gcc.  If you try to divide by zero, they call __div0, and then
>> return 0.  The default implementation of __div0 does nothing.
>>
>> Other compilers might handle it differently.
>
> I'm using the GNUARM toolchain. Does that mean that a divide by zero
> doesn't result in anything?

Yes, the result is zero.  If you want something more to happen, you can 
provide your own __div0 function:

void __div0 (void)
{
  printf ("Division by zero!\n");
}


Karl Olsen