Where can I find the documentation for interactive execution of iverilog's vvp command

[itviewer]

The file StdIOInterface.java implements interactive communication with the vvp command(when simulating Verilog components).
Where can I find the relevant documents?
The content I searched on Google is almost all iverilog + gtkwave to view the generated waveform, and I can hardly find any help content explaining how to simulate interactively with vvp command.

Thanks.

[hneemann]

The code that exchanges data with Digital via stdio is itself written in verilog, and runs together with the user-generated Verlilog code in the Verilog simulator. You can find the resposible verilog hdl template here.

[itviewer]

Thank you! I will study it.