Question about _IQdiv function.

WeiGuo

Intellectual 2575 points

Dear all

I have questions about the function “_IQdiv " of IQmath Library.

- What happens if I divide with" 0 "?

- How is an overflow absorbed?

Thanks

Wei

over 14 years ago

0 XELA over 14 years ago

TI__Expert 5410 points

Wei,

The IQdiv function will return max value (0x7FFF FFFF) when you divide by zero (basically saturate +ve value).

Also, any division overflow will always saturate.

Cheers,

Alex T.

0 David M. Alter over 14 years ago

TI__Guru 61235 points

Wei,

For _IQdiv:

;; On Exit:    ACC    = Num/Den result in IQ format
;;                    = 0x7FFFFFFF if +ve overflow
;;                    = 0x80000000 if -ve overflow
;;                    = 0x7FFFFFFF if Den == 0

This behavior should be documented in the IQmath user's guide, but I see that it is not.

Regards,

David

0 WeiGuo over 14 years ago in reply to David M. Alter

TI__Intellectual 2575 points

Thanks for all of your reply.

We may need to put such info into user's guide.

Cheers,

Wei

0 Kaveh Vaghefi over 11 years ago in reply to WeiGuo

Expert 1704 points

On this topic, what would be the output of _IQdiv(0, 0)? Is it defined?

0 XELA over 11 years ago in reply to Kaveh Vaghefi

TI__Expert 5410 points

A denominator of zero always returns max +ve value, irrespective of the numerator value.

So _IQdiv(0, 0) returns max +ve value (0x7FFFFFFF).

Cheers,

Alex T.

0 Kaveh Vaghefi over 11 years ago in reply to XELA

Expert 1704 points

What about _IQdiv(-0,0) or _IQdiv(-1,0)? Would those still return the max positive value? Is this documented anywhere?

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Question about _IQdiv function.