Interface to the C implementation of Ryu at:
https://github.com/ulfjack/ryu/tree/master/ryu.

The files d2fixed.c, generic_128.c and ryu/generic_128.h have received
some superficial modifications because some perl builds do not honor
the permissiveness of "C99 mode".

This implementation is not currently usable with perl builds whose
$Config{nvsize} > 8.

Building Math::Ryu also requires that the __uint128_t data type
is available.
Therefore 32-bit builds of perl are also unable to use this
implementation.

Otherwise, you can build with:

$ cpan -i Math::Ryu