gEDA-user: Re: [icarus] completely open source fpga toolchain

[Stephen Williams <steve@icarus.com>]

This is pretty kool. You've got a big job in front of you!

Adam Megacz wrote:
> So, now that the abits work is published [1] I plan on turning my
> attention to "connecting the dots", so to speak.
> 
> I've pretty much resigned myself to the fact that I'll have to
> implement PAR by hand (VPR has licensing issues, and there are far
> more architecture-portable algorithms now anyways [2]).
> 
> Moving up the stack one more level: are there any open-source
> synthesis (ie technology mapping) tools out there?  How
> Xilinx-specific is Icarus' mapper?  How much effort is it likely to
> take to retarget it to Atmel CLB's?  My first impulse is to start with
> that, but I figured I'd check here in case anybody has any hints on a
> better route to take.

The v0.8 releases of Icarus Verilog have decent synthesis. The
synthesis is not at all Xilinx specific, but the code generators
are. But they needn't be. The FPGA target generates EDIF, so if
your intermediate form takes EDIF, the way to move forward is to
work on the fpga code generator to generate code for your device.

Or you can write a code generator from scratch.

Either way is not hard to get started. There is lots of detail,
but it should be pretty easy to get the basics working. You want
to look at the ivl_target.h header file which defines the loadable
target API.

CAVEAT: Synthesis in the devel trunk is broken, and has been
temporarily abandoned. There was until very recently precious
little interest in synthesis, so I didn't let it get in the way
of the other tasks I've been working on. Getting synthesis back
on line with the devel branch should be a big job.

Therefore, for now I recommend using the 0.8 branch for synthesis
work, at least for a proof of concept. If there is interest in
putting serious work into it, then getting 0.9 synthesis together
can be worked out later.

-- 
Steve Williams                "The woods are lovely, dark and deep.
steve at icarus.com           But I have promises to keep,
http://www.icarus.com         and lines to code before I sleep,
http://www.picturel.com       And lines to code before I sleep."


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