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--- chess:programming:pawn_hash_table [2021/10/12 12:42] – peter
+++ chess:programming:pawn_hash_table [2022/01/06 21:54] (current) – peter
@@ Line 56: / Line 56: @@
 }
 </code>
+----
+Information to store include:
+  * Color information.
+  * It might be useful to hash the king positions,when much of your pawn evaluation depends on king positions.
+Without king positions in pseudo-C
+<code>
+hash_t RandomIndex[64][2];  // Initialize by Pseudo random numbers.
+  PawnHashIndex = 0;
+  for (pos = A1; pos <= H8; pos++)
+    if (figure[pos] == pawn)
+      PawnHashIndex ^= RandomIndex[pos][color[pos]];
+</code>
+Probably do not do this after every move.
+If you move a pawn , you can update the PawnHashIndex by
+<code>
+// Update the pawn hash for "normal" pawn move.
+PawnHashIndex ^= RandomIndex[from][side]; // Clear the old pawn position.
+PawnHashIndex ^= RandomIndex[to][side];   // Put in the new pawn position.
+</code>
+Similar code is needed for captures of a pawn and pawn promotions.