Some comments

[casevh]

I'm still building PyPy so I haven't tried the code yet.

I looked at the code and I have a couple of comments based on my experiences with gmpy/gmpy2.

When deleting an object, you should check the size of the object before deciding to save it. When I first added caching to gmpy, I didn't make the size check and consumed all memory when someone began working with very large numbers.

When converting a PyLong to an mpz, I access the internal structure - fast but not portable. Have you looked at the int.to_bytes method available in Python 3.x? It might be faster than repeated divmod. If you don't want to be version dependent, have you tried a combination of & and right shift?

I'll try to provide some additional comments after PyPy is running.

I'm impressed by how clean the CFFI code looks.

Case

[sn6uv]

Thanks for the tips. The combination of rightshift and & caused about a 10x speedup assigning large mpzs (granted we're still about 3000x slower than gmpy/gmpy2).

I've been talking to the PyPy / cffi people, and hopefully we can improve the performance. I doubt we'll ever match gmpy's hand tuned C, but hopefully we can get it a bit closer.