From 3fd43cd5fcb22bb65bf2a92a25d95d801b11c9e0 Mon Sep 17 00:00:00 2001
From: Scott Gasch <scott.gasch@gmail.com>
Date: Wed, 1 Jun 2016 18:58:58 -0700
Subject: Initial checkin for typhoon chess engine.

---
 src/pawnhash.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100755 src/pawnhash.c

(limited to 'src/pawnhash.c')

diff --git a/src/pawnhash.c b/src/pawnhash.c
new file mode 100755
index 0000000..8af2138
--- /dev/null
+++ b/src/pawnhash.c
@@ -0,0 +1,53 @@
+/**
+
+Copyright (c) Scott Gasch
+
+Module Name:
+
+    pawnhash.c
+
+Abstract:
+
+    Pawn structure score hashing code.
+
+Author:
+
+    Scott Gasch (scott.gasch@gmail.com) 14 Jun 2004
+
+Revision History:
+
+    $Id: pawnhash.c 345 2007-12-02 22:56:42Z scott $
+
+**/
+
+#include "chess.h"
+
+
+PAWN_HASH_ENTRY *
+PawnHashLookup(SEARCHER_THREAD_CONTEXT *ctx) 
+/**
+
+Routine description:
+
+    Called by eval with a pointer to a POSITION, look in our pawn hash
+    to see if we have an entry that matches the pawn structure in the
+    POSITION.  If so, "check out" that entry and return a pointer to
+    it.
+
+    Note: there is a multi-probing scheme in place to remove
+    contention on MP machines.
+
+Parameters:
+
+    POSITION *pos
+
+Return value:
+
+    PAWN_HASH_ENTRY *
+
+**/
+{
+    POSITION *pos = &(ctx->sPosition);
+    ULONG u = (ULONG)pos->u64PawnSig & (PAWN_HASH_TABLE_SIZE - 1);
+    return(&(ctx->rgPawnHash[u]));
+}
-- 
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