modem_engine_diagram.dot

digraph modem_engine {
    rankdir=TB;
    node [shape=box];

    Init [label="Initialize State and Variables"];
    CheckCmd [label="Check for Incoming Commands"];
    ProcessCmd [label="Process Incoming Commands and Internal Logic"];
    SampleInput [label="Sample Audio/Float Input"];
    ProcessSamples [label="Discriminate and Process Received Samples"];
    ErrorCheck [label="De-interleave and Error Check"];
    HandleData [label="Handle Received ALE Words"];
    PrepareData [label="Prepare Data for Transmission"];
    Modulate [label="Modulate and Output Data"];
    ManageBuffers [label="Manage Buffers and State"];

    Init -> CheckCmd;
    CheckCmd -> ProcessCmd;
    ProcessCmd -> SampleInput;
    SampleInput -> ProcessSamples;
    ProcessSamples -> ErrorCheck;
    ErrorCheck -> HandleData;
    HandleData -> PrepareData;
    PrepareData -> Modulate;
    Modulate -> ManageBuffers;
    ManageBuffers -> Init [label="loop back", color="blue"];
}