connect_rpc - connect to RPC frontend

yosys> help connect_rpc

connect_rpc -exec <command> [args...]
connect_rpc -path <path>
Load modules using an out-of-process frontend.
-exec <command> [args...]
run <command> with arguments [args...]. send requests on stdin, read
responses from stdout.
-path <path>
connect to Unix domain socket at <path>. (Unix)
connect to bidirectional byte-type named pipe at <path>. (Windows)
A simple JSON-based, newline-delimited protocol is used for communicating with
the frontend. Yosys requests data from the frontend by sending exactly 1 line
of JSON. Frontend responds with data or error message by replying with exactly
1 line of JSON as well.

    -> {"method": "modules"}
    <- {"modules": ["<module-name>", ...]}
    <- {"error": "<error-message>"}
        request for the list of modules that can be derived by this frontend.
        the 'hierarchy' command will call back into this frontend if a cell
        with type <module-name> is instantiated in the design.

    -> {"method": "derive", "module": "<module-name">, "parameters": {
        "<param-name>": {"type": "[unsigned|signed|string|real]",
                           "value": "<param-value>"}, ...}}
    <- {"frontend": "[rtlil|verilog|...]","source": "<source>"}}
    <- {"error": "<error-message>"}
        request for the module <module-name> to be derived for a specific set of
        parameters. <param-name> starts with \ for named parameters, and with $
        for unnamed parameters, which are numbered starting at 1.<param-value>
        for integer parameters is always specified as a binary string of
        unlimited precision. the <source> returned by the frontend is
        hygienically parsedby a built-in Yosys <frontend>, allowing the RPC
        frontend to return anyconvenient representation of the module. the
        derived module is cached,so the response should be the same whenever the
        same set of parameters is provided.