Extend book to 48 piece types and 256 squares

Before the Zobrist key could only handle 24 piece types and 128 squares.

diff --git a/book.c b/book.c
index dc81458..8872d16 100644 (file)
--- a/book.c
+++ b/book.c
@@ -328,7 +328,8 @@ hash (int moveNr)
                    pieceGroup = p_enc / 12;
                    p_enc      = p_enc % 12;
                    Zobrist = RandomPiece[64*p_enc + (squareNr & 63)];
-                   switch(pieceGroup) {
+                   if(pieceGroup & 4) Zobrist *= 987654321;
+                   switch(pieceGroup & 3) {
                        case 1: // pieces 5-10 (FEACWM)
                                Zobrist = (Zobrist << 16) ^ (Zobrist >> 48);
                                break;
@@ -339,7 +340,8 @@ hash (int moveNr)
                                Zobrist = (Zobrist << 48) ^ (Zobrist >> 16);
                                break;
                    }
-                   if(squareNr >= 64) Zobrist = (Zobrist << 8) ^ (Zobrist >> 56);
+                   if(squareNr &  64) Zobrist = (Zobrist << 8) ^ (Zobrist >> 56);
+                   if(squareNr & 128) Zobrist = (Zobrist << 4) ^ (Zobrist >> 60);
                    // 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