/// UCI::loop() waits for a command from stdin, parses it and calls the appropriate
/// function. Also intercepts EOF from stdin to ensure gracefully exiting if the
/// GUI dies unexpectedly. When called with some command line arguments, e.g. to
/// run 'bench', once the command is executed the function returns immediately.
/// In addition to the UCI ones, also some additional debug commands are supported.
internal static void loop(string args)
{
var pos = new Position(StartFEN, false, ThreadPool.main()); // The root position
string token = string.Empty;
do
{
try
{
string cmd;
if (args.Length > 0)
{
cmd = args;
}
else if (null == (cmd = Console.ReadLine())) // Block here waiting for input
{
cmd = "quit";
}
var stack = Position.CreateStack(cmd);
if (stack.Count == 0)
{
continue;
}
token = stack.Pop();
// The GUI sends 'ponderhit' to tell us to ponder on the same move the
// opponent has played. In case Signals.stopOnPonderhit is set we are
// waiting for 'ponderhit' to stop the search (for instance because we
// already ran out of time), otherwise we should continue searching but
// switching from pondering to normal search.
if (token == "quit" || token == "stop" || (token == "ponderhit") && Search.Signals.stopOnPonderhit)
{
Search.Signals.stop = true;
ThreadPool.main().notify_one(); // Could be sleeping
}
else if (token == "ponderhit")
{
Search.Limits.ponder = false; // Switch to normal search
}
else if (token == "uci")
{
Output.Write("id name ");
Output.Write(Utils.engine_info(true));
Output.Write("\n");
Output.Write(OptionMap.Instance.ToString());
Output.WriteLine("\nuciok");
}
else if (token == "ucinewgame")
{
Search.reset();
TimeManagement.availableNodes = 0;
}
else if (token == "isready")
{
Output.WriteLine("readyok");
}
else if (token == "go")
{
go(pos, stack);
}
else if (token == "position")
{
position(pos, stack);
}
else if (token == "setoption")
{
setoption(stack);
}
// Additional custom non-UCI commands, useful for debugging
else if (token == "flip")
{
pos.flip();
}
else if (token == "eval")
{
Output.WriteLine(Eval.trace(pos));
}
else if (token == "bench")
{
Benchmark.benchmark(pos, stack);
}
else if (token == "d")
{
Output.Write(pos.displayString());
}
else if (token == "perft")
{
token = stack.Pop(); // Read depth
var ss =
Position.CreateStack(
$"{OptionMap.Instance["Hash"].v} {OptionMap.Instance["Threads"].v} {token} current perft");
Benchmark.benchmark(pos, ss);
}
else
{
Output.Write("Unknown command: ");
Output.WriteLine(cmd);
}
}
catch (Exception ex)
{
Console.Error.WriteLine($"An error occurred: {ex}");
}
} while (token != "quit" && args.Length == 0); // Passed args have one-shot behaviour
ThreadPool.main().join(); // Cannot quit whilst the search is running
}