Re: Quick inverse square root

["Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>]

On 1/3/21 11:31 PM, Matt Borchers wrote:
> 
> Thank you Jeff and Dmitry.  I have a generic functioning now.

Glad to have been of help.

Regarding the unsigned type, it seems this only works if F'Size = 32 or 64, so 
you could write versions that use Unsigned_32 and Unsigned_64, and then make 
your generic function do

if F'Size = 32 then
    return QISR32 (A);
elsif F'Size = 64 then
    return QISR64 (A);
else
    raise Program_Error with "F'Size must be 32 or 64";
end if;

But I don't understand why this exists. In what way is it better than the 
(inverse) Sqrt operation of the FPU?

-- 
Jeff Carter
"I'm a kike, a yid, a heebie, a hook nose! I'm Kosher,
Mum! I'm a Red Sea pedestrian, and proud of it!"
Monty Python's Life of Brian
77