On 23/04/18 15:15, Dennis Lee Bieber wrote:
> On Mon, 23 Apr 2018 11:56:51 +0100, The Natural Philosopher
>  declaimed the following:
>
>>
>> I didnt realise ARM has no div instruction
>>
>
>  It has them (at least ARMv8) but some of the behavior may require use
> of a subroutine to be rigorous.
>
> """
> The integer divide instructions compute (numerator÷denominator) and deliver
> the quotient, which is rounded towards zero. The remainder may then be
> computed as numerator–(quotient
> denominator) using the MSUB instruction.
>
> If a signed integer division (INT_MIN ÷ -1) is performed, where INT_MIN is
> the most negative integer value representable in the selected register
> size, then the result will overflow the signed integer range. No indication
> of this overflow is produced and the result written to the destination
> register will be INT_MIN.
>
> NOTE: The divide instructions do not generate a trap upon division by zero,
> but write zero to the destination register.
> """
>
>  At the very least, many higher level languages expect division by zero
> to raise a condition -- so a subroutine would likely be used incorporating
> the needed testing and flag setting rather than emitting the same common
> code every time a divide was done.
>
>
That is fair comment, yes.


--
"A point of view can be a dangerous luxury when substituted for insight
and understanding".

Marshall McLuhan

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