Is there a good lib out there to handle large integer of know size ?

[Era Scarecrow via Digitalmars-d]

On Sunday, 11 June 2017 at 18:01:41 UTC, Era Scarecrow wrote:
>  And what timing, I just finished getting it working with 
> assembly and compatible versions. Seems 5x slower rather than 
> the dreaded 50, but that's from testing factorial up to 100 
> (200ms vs 1,200ms).

  Doing a 10240bit int I ran though 1,000 factorials in 6 seconds 
(this includes printing the values out). I got to about 400 in 16 
minutes using the generic code. So like the wideint 
implementation I saw a while ago, larger types aren't 
recommended, but the speed penalty you can live with to use 
cent/ucent.

  Also got Cent working (mostly). In a few more days I should 
probably have this done. If there's somewhere else i should post 
my work regarding this or updates, do let me know.