From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
To: Libre-RISCV General Development <libre-riscv-dev@lists.libre-riscv.org>
Subject: Re: [libre-riscv-dev] PPC on Talos and Playstation 3
Date: Mon, 30 Mar 2020 19:09:36 +0000
Message-ID: <CAPweEDxQGsJqQYq=KwMzV3MGUCh-6zPPpgK+eh3cNxMUbRO-jw@mail.gmail.com> (raw)
In-Reply-To: <84B46705-7450-49CD-924B-72170B8693A4@gatech.edu>
On Mon, Mar 30, 2020 at 7:57 PM Immanuel, Yehowshua U
<yimmanuel3@gatech.edu> wrote:
>
> > yehowshua, you're aware that by choosing to do this, that you'll be
> > committing over 6 months of your life to the task? that's typically
> > how long it takes (if not longer).
>
> Oh wow! Why so long
https://git.libre-riscv.org/?p=ieee754fpu.git;a=shortlog;pg=19
then page back and watch the months go by.
> - I was thinking maybe 4 weeks…
no chance. we started in february, last year, working from jon
dawson's verilog code and hand-converting it to nmigen. we were
delighted when, a week later, we had working IEEE754 FP add.
by around 2 months we had MUL and a decent pipeline structure. at
some point i worked out how to parameterise the code.
at least 6 weeks were spent writing unit tests.
FPDIV took about 2 months: Jacob wrote some code that does div *and*
sqrt *and* rsqrt, that was about 5 weeks i think? then it took me
about 3 weeks to join it together into FP (jacob's code was
fixed-integer).
then i added integer to fp and fp to integer, and class and FCVT,
those all took around... 2 and a half weeks i think, including unit
tests.
michael recently did FPMAX, FPCMP etc. which was... about a week.
we still have to do SIN, COS, ATAN2, ROOT3, POW, LOG, LOG1P, ACOS and
more. this will be about another 2 months.
> At a minimum, I’d like to at least see how well Bluespec handles FPU configuration.
great - just remember that we're under time pressure and so anything
that means "team has to learn a new language which is KNOWN to cause
massive problems due to its insanely high barrier to entry" has to be
excluded from going into the ASIC.
> The maintainer of BSC has been quite helpful in general - so I should him or her just how flexible is BSC for specifying an FPU…
is that Niraj? he's really good.
l.
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Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-29 20:17 Immanuel, Yehowshua U
2020-03-29 20:20 ` Immanuel, Yehowshua U
2020-03-29 20:35 ` Jacob Lifshay
2020-03-29 21:01 ` Luke Kenneth Casson Leighton
2020-03-30 6:56 ` Lauri Kasanen
2020-03-30 7:12 ` Jacob Lifshay
2020-03-30 7:32 ` Lauri Kasanen
2020-03-30 7:52 ` Jacob Lifshay
2020-03-30 8:05 ` Lauri Kasanen
2020-03-30 18:07 ` Jacob Lifshay
2020-03-30 18:12 ` Immanuel, Yehowshua U
2020-03-30 18:16 ` Jacob Lifshay
2020-03-30 18:35 ` Immanuel, Yehowshua U
2020-03-30 18:36 ` Immanuel, Yehowshua U
2020-03-30 18:46 ` Luke Kenneth Casson Leighton
2020-03-30 18:57 ` Immanuel, Yehowshua U
2020-03-30 19:09 ` Luke Kenneth Casson Leighton [this message]
2020-03-30 19:20 ` Immanuel, Yehowshua U
2020-03-30 19:25 ` Luke Kenneth Casson Leighton
2020-03-30 19:35 ` Immanuel, Yehowshua U
2020-03-30 19:45 ` Jacob Lifshay
2020-03-30 19:46 ` Immanuel, Yehowshua U
2020-03-30 22:02 ` Luke Kenneth Casson Leighton
2020-03-30 19:01 ` Jacob Lifshay
2020-03-30 19:20 ` Luke Kenneth Casson Leighton
2020-03-31 21:57 ` Michael Nolan
2020-03-31 23:01 ` Luke Kenneth Casson Leighton
2020-04-01 0:23 ` Immanuel, Yehowshua U
2020-04-01 0:44 ` [libre-riscv-dev] additional ddr3 interfaces Jacob Lifshay
2020-04-01 0:47 ` Immanuel, Yehowshua U
2020-04-01 1:01 ` Jacob Lifshay
2020-04-01 11:10 ` Luke Kenneth Casson Leighton
2020-04-01 15:19 ` Staf Verhaegen
2020-04-01 15:42 ` Luke Kenneth Casson Leighton
2020-04-01 11:00 ` [libre-riscv-dev] PPC on Talos and Playstation 3 Luke Kenneth Casson Leighton
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