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How to implement KPK ?
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H.G.Muller



Joined: 10 Mar 2006
Posts: 20720
Location: Amsterdam

PostPost subject: Re: How to implement KPK ?    Posted: Thu Mar 21, 2013 11:52 am Reply to topic Reply with quote

Ah, you make use of left-right symmetry. Nice idea. I now did that too, by adding a >>1 to the Pawn square during packing, and incrementing it in steps of 2. This should throw away all positions where the Pawn is on an odd file. (A bit wasteful, as the generation still uses the full set of positions, but the assumption was this would be infinitely fast anyway, or that speed would not be important because you save it on a file.)

The following code is tested in the sense that it compiles (there was a missing semicolon), and runs without segfaulting (I had forgotten to convert the 0x88 to-square back to a normal square index.)

Code:
/* Public-domain KPK bitbase code by H.G. Muller */

#define WTM 0
#define BTM 1

char dtc[2][64][64][64]; // 512 KB
char bitbase[2*64*64*3];

char steps[] = {1, -1, 16, -16, 15, -15, 17, -17};

void
Init ()
{
  int wk, bk, p;
  for(wk=0; wk<64; wk++) for(bk=0; bk<64; bk++) for(p=0; p<64; p++) {
    if(bk == wk) dtc[BTM][wk][p][bk] = 1, dtc[WTM][wk][p][bk] = -1; else
    if(wk == p) dtc[BTM][wk][p][bk] = dtc[WTM][wk][p][bk] = -1; else
    if(bk ==  p) dtc[BTM][wk][p][bk] = -1; else // with WTM black just captured P
    if(p >= 56) dtc[WTM][wk][p][bk] = 1; // promoted and on move = win
  }
}

void
Pass (int stm)
{
  int wk, bk, p, d;
  for(wk=0; wk<64; wk++) for(bk=0; bk<64; bk++) for(p=0; p<64; p++) {
    int k = stm == WTM ? wk : bk;
    int O88 = (k & 070) + k; // 0x88 square number of King
    if(dtc[stm][wk][p][bk]) continue; // already decided
    dtc[stm][wk][p][bk] = stm;  // assume lost if btm, undecided if wtm
    if(bk != p && stm == WTM) { // pawn not captured, so can move
      if(p+8 != bk && dtc[BTM][wk][p+8][bk] > 0)  { dtc[WTM][wk][p][bk] = 1; continue; }
      if(p+7 == bk && (p & 7) != 0)  { dtc[WTM][wk][p][bk] = 1; continue; }
      if(p+9 == bk && (p & 7) != 7)  { dtc[WTM][wk][p][bk] = 1; continue; }
    }
    for(d=0; d<8; d++) {
      int to = O88 + steps[d];
      if(to & 0x88) continue; // off board
      to -= to>>1 & 070;
      if(stm == WTM ? dtc[BTM][to][p][bk] > 0 : dtc[WTM][wk][p][to] > 0)
      { dtc[stm][wk][p][bk] = !stm; break; }
    }
  }
}

void
Pack ()
{
  int wk, bk, p, i;
  for(wk=0; wk<64; wk++) for(bk=0; bk<64; bk++) for(p=8; p<56; p+=2) {
    int index = (bk >> 3) + 8*wk + 8*64*(p-8>>1);
    bitbase[2*index] |= (dtc[WTM][wk][p][bk] > 0) << (bk & 7);
    bitbase[2*index+1] |= (dtc[BTM][wk][p][bk] > 0) << (bk & 7);
  }
}

void
Build ()
{
  int i;
  Init();
  for(i=0; i<100; i++) // won't take more than 100 moves
    Pass(WTM), Pass(BTM);
  Pack();
}


When I run it, it prints

Code:
white to move: 211980+, 23085=, 27079-
black to move: 140386+, 113694=, 8064-


where = and - together count the non-won positions (which are not properly distinguished by the algorithm), and + the number of listed wins.

[Edit] O, I guess it still needs a stalemate correction.
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Display posts from previous:   
Subject Author Date/Time
How to implement KPK ? Chan Rasjid Thu Mar 21, 2013 3:43 am
      Re: How to implement KPK ? H.G.Muller Thu Mar 21, 2013 7:46 am
            Re: How to implement KPK ? Chan Rasjid Thu Mar 21, 2013 8:27 am
                  Re: How to implement KPK ? H.G.Muller Thu Mar 21, 2013 10:07 am
                        Re: How to implement KPK ? H.G.Muller Thu Mar 21, 2013 10:33 am
                        Re: How to implement KPK ? Chan Rasjid Thu Mar 21, 2013 6:10 pm
                              Re: How to implement KPK ? Don Dailey Tue Apr 02, 2013 6:56 pm
            Re: How to implement KPK ? Lucas Braesch Thu Mar 21, 2013 11:03 am
                  Re: How to implement KPK ? H.G.Muller Thu Mar 21, 2013 11:52 am
                        Re: How to implement KPK ? Lucas Braesch Thu Mar 21, 2013 12:04 pm
                        Re: How to implement KPK ? H.G.Muller Thu Mar 21, 2013 6:36 pm
                              Re: How to implement KPK ? H.G.Muller Thu Mar 21, 2013 9:00 pm
                              Re: How to implement KPK ? Chan Rasjid Sat Mar 30, 2013 8:15 am
                                    Re: How to implement KPK ? Evert Glebbeek Sat Mar 30, 2013 8:42 am
                                          Re: How to implement KPK ? Sven Schüle Sat Mar 30, 2013 12:12 pm
                                                Re: How to implement KPK ? Chan Rasjid Sat Mar 30, 2013 12:20 pm
                                                      Re: How to implement KPK ? Sven Schüle Sat Mar 30, 2013 12:42 pm
                                                            Re: How to implement KPK ? Chan Rasjid Sat Mar 30, 2013 2:03 pm
                                                                  Re: How to implement KPK ? Sven Schüle Sat Mar 30, 2013 6:29 pm
                                                      Re: How to implement KPK ? Wylie Garvin Sat Mar 30, 2013 12:50 pm
                                                            Re: How to implement KPK ? Chan Rasjid Sat Mar 30, 2013 1:53 pm
                                                Re: How to implement KPK ? Evert Glebbeek Sat Mar 30, 2013 2:03 pm
                                                      Re: How to implement KPK ? H.G.Muller Sat Mar 30, 2013 2:26 pm
                                                            Re: How to implement KPK ? Sven Schüle Sat Mar 30, 2013 6:38 pm
                                                                  Re: How to implement KPK ? H.G.Muller Sat Mar 30, 2013 8:13 pm
                                                                        Re: How to implement KPK ? Sven Schüle Sat Mar 30, 2013 8:58 pm
                                                                              Re: How to implement KPK ? H.G.Muller Sat Mar 30, 2013 10:58 pm
                                                                                    Re: How to implement KPK ? Sven Schüle Sat Mar 30, 2013 11:51 pm
                                                                                          Re: How to implement KPK ? H.G.Muller Sun Mar 31, 2013 7:35 am
                                                                                          Re: How to implement KPK ? Sven Schüle Sun Mar 31, 2013 9:02 am
                                                                                          Re: How to implement KPK ? H.G.Muller Sun Mar 31, 2013 9:09 am
                                                                                          Re: How to implement KPK ? Sven Schüle Sun Mar 31, 2013 9:13 am
                                                                                          Re: How to implement KPK ? Steven Edwards Mon May 13, 2013 2:14 am
                                                                                          Re: How to implement KPK ? Don Dailey Mon May 13, 2013 2:20 am
                                          Re: How to implement KPK ? Chan Rasjid Sat Mar 30, 2013 12:18 pm
                                    Re: How to implement KPK ? H.G.Muller Sat Mar 30, 2013 9:08 am
      Re: How to implement KPK ? Chan Rasjid Sun May 12, 2013 10:27 pm
            Re: How to implement KPK ? Ronald de Man Sun May 12, 2013 11:11 pm
                  Re: How to implement KPK ? Chan Rasjid Mon May 13, 2013 7:39 am
            Re: How to implement KPK ? Don Dailey Mon May 13, 2013 2:14 am
            Re: How to implement KPK ? Steven Edwards Tue May 14, 2013 7:19 am
                  Re: How to implement KPK ? Chan Rasjid Tue May 14, 2013 2:45 pm
                        Re: How to implement KPK ? Chan Rasjid Tue May 14, 2013 2:50 pm
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