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switch c++ chess game

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Started by Moagly February 03, 2003 08:06 AM

0 comments, last by Moagly 21 years, 2 months ago

Moagly

160

Author

February 03, 2003 08:06 AM

I am creating a chess game using c++, i am going to be using the ray method for move generation as described in the chess programming series in artificial intelligence section on gamedev, i was wondering which would be the quickest(in terms of CPU execution) this way using switch statements :

  

// one of these for each piece

bool makeKingMoves(square, ray)
{

   switch(square)
   {
      case 0 :
      {
         switch(ray)
         { 
            case 0 : destination = 8;
            case 1 : destination = 1;
            // etc, etc... u get the picture

         }
      case 1 : 
      {
         switch(ray)
         {
            case 0 : destination = 0;
            case 1 : destination = 8;
            // etc, etc

         }
      }
   
      // and so on and so forth for the entire board

   }
}

or this way using arrays :

  

kingMoves[0][0] = 8;
kingMoves[0][1] = 1;

I guess my question is basically how does the switch statement in c++ work, how slow is it? If anyone has any ideas or thoughts wud be greatly appreciated.

Jan Wassenberg

1,000

February 03, 2003 10:45 AM

That switch statement will end up huge (64 sq * 8 rays).
Anyway, switch can be implemented as a chain of cmp/jcc, as a decision tree, or by means of a jump table (if there are lots of values in a tight range).

I don''t think performance matters here - it''s just a one time init thing.

Here''s how I did it (yuck

)

for each square on board (padded => no move leads ''out of bounds'')  for each piece (w pawn, b pawn, all others)    for each ray (dependent on piece)      do        advance along ray        if on valid square          SETBIT(move_array[piece][from_sq], to_sq)      while(piece is ranged && on valid square)

Hope that helps a little

Jan

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switch c++ chess game

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