Take account of holdings in book key

The board is numbered by rank, for comptibility with Polyglot format,
starting at a1. We then continue counting in the holdings 'files', in
up-rank direction, each holding spanning the full board height (even if
it is not fully used). Firstthe left (black) holdings, then the right,
Even in Shogi this limits the square number to < 99, which is below the
absolute limit of 128 (where we would run out of hash keys).

diff --git a/book.c b/book.c
index e5a6030..3a764b9 100644 (file)
--- a/book.c
+++ b/book.c
@@ -276,17 +276,21 @@ uint64 *RandomTurn      =Random64+780;
 uint64 hash(int moveNr)
 {
     int r, f, p_enc, squareNr, pieceGroup;
-    uint64 key=0, Zobrist;
+    uint64 key=0, holdingsKey=0, Zobrist;
 
-    for(f=BOARD_LEFT; f<BOARD_RGHT; f++){
+    for(f=0; f<BOARD_WIDTH; f++){
         for(r=0; r<BOARD_HEIGHT;r++){
             ChessSquare p = boards[moveNr][r][f];
+           if(f == BOARD_LEFT-1 || f == BOARD_RGHT) continue; // between board and holdings
             if(p != EmptySquare){
                    int j = (int)p;
                    j -= (j >= (int)BlackPawn) ? (int)BlackPawn :(int)WhitePawn;
                    if(j > (int)WhiteQueen) j++;  // make space for King
                    if(j > (int) WhiteKing) j = (int)WhiteQueen + 1;
                    p_enc = 2*j + ((int)p < (int)BlackPawn);
+                   // holdings squares get nmbers immediately after board; first left, then right holdings
+                   if(f == BOARD_LEFT-2) squareNr = (BOARD_RGHT - BOARD_LEFT)*BOARD_HEIGHT + r; else
+                   if(f == BOARD_RGHT+1) squareNr = (BOARD_RGHT - BOARD_LEFT + 1)*BOARD_HEIGHT + r; else
                    squareNr = (BOARD_RGHT - BOARD_LEFT)*r + (f - BOARD_LEFT);
                    // note that in normal Chess squareNr < 64 and p_enc < 12. The following code
                    // maps other pieces and squares in this range, and then modify the corresponding
@@ -306,11 +310,13 @@ uint64 hash(int moveNr)
                                break;
                    }
                    if(squareNr >= 64) Zobrist = (Zobrist << 8) ^ (Zobrist >> 56);
+                   // holdings have separate (additive) key, to encode presence of multiple pieces on same square
+                   if(f == BOARD_LEFT-2) holdingsKey += Zobrist * boards[moveNr][r][f+1]; else
+                   if(f == BOARD_RGHT+1) holdingsKey += Zobrist * boards[moveNr][r][f-1]; else
                 key ^= Zobrist;
             }
         }
     }
-    // Holdings not implemented yet!
 
     if(boards[moveNr][CASTLING][2] != NoRights) {
        if(boards[moveNr][CASTLING][0] != NoRights) key^=RandomCastle[0];
@@ -341,7 +347,7 @@ uint64 hash(int moveNr)
     if(WhiteOnMove(moveNr)){
         key^=RandomTurn[0];
     }
-    return key;
+    return key + holdingsKey;
 }
 
 #define MOVE_BUF 100