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Message
From: Tom Hawkins<tom@l...>
Date: Tue May 18 14:57:42 CEST 2004
Subject: [oc] Re: RCA project
On Monday 17 May 2004 06:59 pm, you wrote:
> Are you still doing anything with the RCA project on opencores? I'm
> a software guy with an itch to learn about configurable hardware,
> and it looked interesting. Do you have any examples of the
> hand-implemented RCA designs you mention, such as the adder?
Hi Phil,
I haven't updated the core in awhile, but lately I've been considering
what it would take to write a compiler for RCA. (I don't even know
what the input language would be.)
The only examples I have are hand drawn. I would recommend sitting
down with some graph paper to sketch out a few -- I've found this to
be an enlightening experience in architecture design.
The architecture is fairily basic, so it's easy to get started. Each
tile has a 3:1 LUT and a state register for each direction (north,
south, west, and east) for a total of 4 LUTs and states regs per
tile. The mulitplexers and the LUT functions are programmable.
For example, an adder could look like this (Xs are tiles):
These are the inputs:
a3 --> X <-- b4
a2 --> X <-- b3
a1 --> X <-- b2
a0 --> X <-- b0
^
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c_in ---
These are the outputs:
----> c_out
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X --> x4
X --> x3
X --> x2
X --> x0
Due to the unit delays between tiles, the input data need to be skewed
accordingly. The state register is commonly used for de-skewing the
pipeline during data routing.
--
Tom Hawkins
Launchbird Design Systems, Inc.
Home of the Confluence Logic Design Language
http://www.launchbird.com/
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