[Libre-soc-bugs] [Bug 782] add galois field bitmanip instructions

[bugzilla-daemon at libre-soc.org]

https://bugs.libre-soc.org/show_bug.cgi?id=782

--- Comment #41 from Jacob Lifshay <programmerjake at gmail.com> ---
though, do we really need gfdiv? it's a lot of extra complexity and i can't
think of any algorithms that need it...if there are algorithms, they can easily
run gfmul on the result of gfinv, giving the equivalent of gfdiv.

In any case, here's the list of binary gf ops I think we should implement:

* clmul, clmulh (for gf operations that are > 64-bit, and other stuff)
* gfbmul RT, RA, RB
* gfbmuli RT, RA, imm # discard if we don't have enough encoding space
* gfbmadd RT, RA, RB, RC
* gfbinv rt, ra
    input 0 gives result 0 even though that is division by zero,
    that's what's needed for AES.

gfbadd is covered by the existing xor instructions.
gfbmaddsubr is not needed, since sub is identical to add, this is just two
gfbmadd instructions.

If that all sounds good, i can create a new tracking bug for binary gf
instructions and start working on implementing them.

-- 
You are receiving this mail because:
You are on the CC list for the bug.