[libre-riscv-dev] div/mod algorithm written in python

[Jacob Lifshay]

I got everything working! I disabled the frsqrt test for fp64 since we
don't have a proper reference implementation yet. fp32 and fp16 seem
to work well enough for now by emulating using fp64 arithmetic, but
it's NOT GUARANTEED TO WORK.
it was a single giant messy commit, so I pushed to the
messy-div-pipe-works branch instead of master.
I'll split it up properly tomorrow.

Would you consider this good enough to declare the frsqrt, fsqrt, and
fdiv bugs resolved for now?

I still want to build in SIMD capabilities like the multiplier and
support fp64 operations by running them through the pipeline twice.

Also, integer division is not implemented yet.

Jacob Lifshay