use WASM to run simulation on the web

[aghangurde]

Precedent for verilator and yosys

• https://github.com/sehugg/8bitworkshop/blob/614991b8e856d795288e2e2554a3e12e23076bce/src/worker/wasm/verilator_bin.wasm
• https://yowasp.org/

Iverilog seems doable with emscripten.

The logic in simulate.js doesn't seem to be anytthing that can't be done on browser platform (Posting here to see if anyone else has worked on this, otherwise I will start and report back on success/failure)

[aghangurde]

Update: I was able to compile verilator using emscripten to wasm.

However as verilator outputs cpp, we need emscripten again inside of emscripten to compile the verilator output. I am investigating emception.

Update: iverilog compiled

[aghangurde]

Update: verilator seems to be linting properly in nodejs.

[norandomtechie]

Sorry I haven't been keeping track of this... Good work so far. Glad you're making progress.

I had the same idea a few years ago. Verilator and Yosys will work in WASM - I actually built in Verilator linting into your ece270 assignments on the engineering.purdue.edu/ece270 website, which is how the Test button works on Verilog assignments.

But the problem is iverilog. Icarus Verilog is not a single program - if I remember right, it's a bunch of other binaries that you have to compile into the WASM container, and something about it was not simple to do. Hopefully you surpass it though.

[aghangurde]

iverilog essentially runs ivlpp (Preprocess) and then Elaboration which outputs the generated vvp code. Then you must manually execute vvp to actually simulate the code. This should be doable, but it isn't trivial. Easiest would be to apply a patch to the iverilog program that will return the arguments needed to pass to the preprocessor and then the code generator.