Add skins for missing Yosys RTL cells about netlistsvg

[mithro]

This looks awesome!

[nobodywasishere]

So I've worked a little bit more on this, specifically on the latches / flip-flops. For latches/ffs with a reset, I've just added a port onto the bottom that can be populated if it exists, and I've not distinguished between synchronous and asynchronous (yet). I also added -bus variants for these.

Here's an example of one diagram before:

And after:

[mithro]

All looks pretty awesome to me!

[mithro]

@nobodywasishere - I'm sure I had some of these already created somewhere but I can't seem to find them now....

[mithro]

Apparently I had some stuff at mithro/symbiflow-arch-defs@bd58242?short_path=e0d91d8#diff-e0d91d811dd290812325d4ed53ad63fc429631785ea6edaf4c835205aef59563

[mithro]

[mithro]

There seems to be some documentation at https://github.com/mithro/symbiflow-arch-defs/blob/4ac22bdc2f6261c09db5f00034b52c66d5f482ce/vpr/latches/README.md

[mithro]

https://raw.githubusercontent.com/mithro/symbiflow-arch-defs/f47a4e1539c844aac164692f4fdb164f19740861/common/svg/default.svg

[mithro]

https://raw.githubusercontent.com/mithro/symbiflow-arch-defs/277b176d04243067af4bd37f12be03347275593f/common/netlistsvg.svg

[mithro]

And on the topic of flip flops and latches - I have a giant table of flip flops and latches found in various FPGA architectures at https://docs.google.com/spreadsheets/d/16yvScRkedOkPCRBSInFuHE_cUMD8Ls-b9KFmHocpC-o/edit#gid=0 and some details about the mapping between them at https://docs.google.com/spreadsheets/d/1pWjU8RujiGdlr-8iG66O1rvognNHgtnNVvCjSfksH-4/edit#gid=0

[mithro]

There is also some code to generate flip flops from the spreadsheet at https://github.com/mithro/symbiflow-arch-defs/blob/v2x-latches2/utils/flipflop-generate.py

[nobodywasishere]

Work in progress here. Thoughts? Still need to work on the flip flops / latches. Thank you for all the information mithro!

[rishubn]

Are there plans to unroll or devise skins for complex gates within the cell library such as AOI3

https://github.com/YosysHQ/yosys/blob/fdb19a5b3a10572b1b84a26306ec5e83a4eff613/manual/CHAPTER_CellLib.tex#L637

[nobodywasishere]

I had not planned on doing those, though I can look into it. Do you have an idea / sketch of what you think it could look like?

[rishubn]

@nobodywasishere

It would make sense to unroll these, currently their are represented as black boxes, but maybe this needs to be done on the algorithm side, not the skins
For example, OAI3:

[mithro]

Some suggestions from a quick google search;

• http://www.vlsi-expert.com/2018/01/aoi-and-or-inverter-cell.html
• https://en.wikipedia.org/wiki/AND-OR-Invert

2-2 AOI Symbol

[mithro]

[nobodywasishere]

Progress update:

• Added $_{AND,OR}NOT_
• Added $_{AOI,OAI}{3,4}_
• Added the fix in #115
• Attempted a memory cell, but not sure how good a representation this is (it's still a WIP)