implementing uci stop command

[elcabesa]

I'm going to modify the command parser of my UCI engine.
My engine is not multithreaded and I don't want now to write a thread for the search and a thread for the parser.
I have some problem with the stop command, I poll during the search for a kbhit() and everything is working nicely except I lose strength.

Do you know something faster than kbhit ?? what can I do?

[Karlo Bala]

I'm going to modify the command parser of my UCI engine.
My engine is not multithreaded and I don't want now to write a thread for the search and a thread for the parser.
I have some problem with the stop command, I poll during the search for a kbhit() and everything is working nicely except I lose strength.

Do you know something faster than kbhit ?? what can I do?

Simple solution, skip the check in the last few plays.

[elcabesa]

I already check for input every 1000 nodes

[hgm]

kbhit() ? Does that work on pipes?

[elcabesa]

I really don't know, I have tested it with console, and with cutechesscli which has not stop command

[hgm]

Well, I don't think it would be any good on pipes. And consequently it is nor very relevant if it is excruciatingly slow or not. My engines use PeekNamedPipe() to check for input on Windows. (But that doesn't work when I run them from the command prompt.) I never tried to measure the slowdown, but I suppose I would have noticed if it was spectacular. (I also check every 1000-4000 nodes. If you knew how long a typical call takes, I suppose you can calculate what the optimum probing rate is, balancing time you lose by probing against time you lose from probing too late.)

[elcabesa]

could you point me to one of yours engine so i can study peeknamedpipe?

thank you

[hgm]

Well, my engines are not open source, except for micro-Max / Fairy-Max, but that does not ponder and so does not use it. But I can post a typical code excerpt here, as it is very short:

Code: Select all

int unbuffered_input(int init)
{  // returns number of waiting input characters (or 1 if call fails)
    static int pipe;
    static HANDLE inp = NULL;
    DWORD cnt;

    if(!inp) inp = GetStdHandle(STD_INPUT_HANDLE);
    if(!PeekNamedPipe(inp, NULL, 0, NULL, &cnt, NULL)) return 1;
    return cnt;
}

// In Search():

            // ABORT
            if((++sample & 0xFFF) == 0) {
                  if(pondering) abortFlag = unbuffered_input(0);
                  else          abortFlag = (GetTickCount() - Ticks > tlim3);
            }

[AlvaroBegue]

For POSIX (read "non-Windows") systems I use this:

Code: Select all

#include <sys/select.h>

bool is_there_input(){
  fd_set read,write,except;
  FD_ZERO(&read);
  FD_ZERO(&write);
  FD_ZERO(&except);
  FD_SET(0,&read); // stdin                                                     

  struct timeval timeout;
  timeout.tv_sec=0;
  timeout.tv_usec=0;

  return select(1,&read,&write,&except,&timeout);
}

[elcabesa]

Why do you talk about pondering? my engine doesnt' ponder but i added the stop command anyway, am I wrong?