Re: [libre-riscv-dev] daily kan-ban update 14may2020

[Tobias Platen <libre-soc@platen-software.de>]

Like Yesterday I am still working on the countzero.vhdl thing.

Tobias

On Thu, 14 May 2020 15:43:33 +0100
Luke Kenneth Casson Leighton <lkcl@lkcl.net> wrote:

> On Thu, May 14, 2020 at 3:23 PM Michael Nolan <mtnolan2640@gmail.com> wrote:
> 
> > Yesterday I worked on connecting the rotator from microwatt up to the
> > shift/rotate unit, fixing bugs in the rotator, and testing it.
> 
> i'm amazed it worked, and also how elegant the microwatt rotator code is.
> 
> > Today I might try working on comparisons, but I'm not sure whether they should
> > be a part of the alu or a separate FU
> 
> i went through the list this morning, and left some TODOs.
> 
> cmpb is different from cmp: cmp is definitely based on add (actually,
> subtract - but see the notes from execute1.vhdl):
> https://github.com/antonblanchard/microwatt/blob/master/execute1.vhdl#L540
> 
> cmp is definitely arithmetic, however cmpb feels like it is a
> logical-thing (and is in fixedlogical)
> https://github.com/antonblanchard/microwatt/blob/master/execute1.vhdl#L657
> https://github.com/antonblanchard/microwatt/blob/master/ppc_fx_insns.vhdl#L735
> https://github.com/antonblanchard/microwatt/blob/master/helpers.vhdl#L117
> 
> 
> btw, you'll like this: because we are doing a parallel processor,
> different Function Units *can* actually cover multiple tasks :)  let's
> not go into that right now, however if we convert power_enum Function
> into an unary field (1<<0, 1<<1, 1<<2) then we can, in the CSV files,
> set multiple bits.
> 
> a good example would be AND and OR and XOR: those are prime candidates
> to put into *both* the Logical *and* Arithmetic pipelines.  recorded
> it for now:
> https://bugs.libre-soc.org/show_bug.cgi?id=310
> 
> l.
> 
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-- 
Tobias Platen <libre-soc[at]platen-software[dot]de>

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