[Libre-soc-dev] bitmanip planning

[Jacob Lifshay]

On Thu, Nov 4, 2021, 15:17 lkcl <luke.leighton at gmail.com> wrote:

>
>
> On November 4, 2021 9:55:44 PM UTC, Jacob Lifshay <
> programmerjake at gmail.com> wrote:
>
> >Lkcl, where is the reference verilog?
>
> much of the complex ones that csme from RISCV xbitmanip went into picorv32
> or into claire wolfe's repos.
>
> gaah this was a pain to find:
>
>
>
> https://github.com/cliffordwolf/xbitmanip/tree/71a19aad81369fbcf71b83e78564e0c8ee1b1b80/verilog


Ah, thx!

>
>
>
> can i recommend starting with ridiculously small and obvious ones like
> bitset / bitclear?


Hmm, sounds good...I was planning on probably starting with the ternary op,
the implementation should be pretty straightforward, though the instruction
encoding might be more trouble. If we're going to support 4-in 1-out ops,
it might be worth having another ternary op where the lookup table is given
by a register rather than an immediate field.

Jacob