Or at least wrap one of the C libs that do it.
Have you found any 128bit math library in good shape? I have been googling for a while and all I have found is very rudimentary. Nothing complete or exploiting the 128bit abilities of modern processors.
gcc seems to have some basic support also, but the documentation about that feature is very poor and does not even state the processors where it is supported.
Well, the thing is that if you are able to find some good 128bits library, building a Math::Int128 module using Math::Int64 as a base should be pretty straight forward. Just point me to the library and I will do it!
BTW, I would also like to see a 256bits module... even if at that size, the performance would be pretty similar to that of a bigint library operating over integers of the same size.