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

[Era Scarecrow via Digitalmars-d]

On Saturday, 10 June 2017 at 19:40:47 UTC, Andrei Alexandrescu 
wrote:
> On 6/10/17 3:28 PM, Era Scarecrow wrote:
>>   Got a possible one. My implementation is heavy on assembly 
>> language to take advantage of x86 features
>
> That's cool as long as the assembler is guarded by 
> version(X_86) and has a portable alternative. Where's the code? 
> -- Andrei

  My computer, and no portable alternative yet. I've got a ways 
before that's an option, probably end up doing 32bit math with 
ulongs to make it work reliably and portably. Worse it will 
probably be 10-50x slower.