Re: Floating point assist exceptions

Hi Michael,

I'm using MPC555 and Diab compiler. You can add the line of ASM code
shown below to enable the NON-IEEE mode of the floating-point
processor. This avoids the FLOATING-POINT ASSIST exceptions that are
intended to invoke software routines to handle denormalized data
values. For real-time applications and deterministic behavior,
enabling NON-IEEE mode tells the CPU to do something reasonable.

// Set NI bit of FPSCR for Non-IEEE floating-point mode
asm( " mtfsb1 29" );	// Non-IEEE mode

I could not find anyone at WindRiver that could answer any questions
about whether there was any support for the sofware assist in the Diab
floating-point routines. There does not appear to be any.

Joe

--- In [email protected], reckerm@... wrote:
>
> Hello all,
> due to a floating point calculation routine with a tiny result i got a 
> floating point assist exception.
> We use lots of float calculation and I don't want to react
individual. I 
> dont know what to do in this exception.
> First question: What should be done there in normal (non-SIE) mode ?
> 
> Second question: What happens,if the SIE Mode (ignores FP
exceptions) is 
> enabled ? Does the floating point unit 
> work in regular operation if no exception occours and just switch to 
> software emulation in case of an exception,
> or is the floating point hardware constantly disabled ? 
> (in SIE mode float divisions take 4,3% longer as i measured)
> 
> Best Regards and many thanks for any idea,
> Michael 
> 
> [Non-text portions of this message have been removed]
>







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