Re: [PATCH] Re: Bignum performance

[Po Lu]

Emanuel Berg <incal@dataswamp.org> writes:

> Po Lu wrote:
>
>>> Are we talking 1 word = 2 bytes = 16 bits here, s2c?
>>>
>>> If so, the range of fixnums are -32 768 to 32 767
>>> inclusive, so those are hardly huge numbers.
>>
>> Under Arm64, general purpose integer registers are 64 bits
>> wide. That is also the word size of said machine.
>
> If they are, the range for fixnums is
>
> (list (* -1 (expt 2 (1- 64)))
>       (1-   (expt 2 (1- 64))) )
>
> (-9223372036854775808 9223372036854775807)
>
> Only after that it gets slower :P

Lisp systems normally set aside several of the high or low bits of a
register as a tag linking a type to the object represented.