From df0135e11e9ea3dd0acab94fdf437451ef7e522b Mon Sep 17 00:00:00 2001
From: Scott Gasch <scott@gasch.org>
Date: Wed, 26 Aug 2026 06:58:26 -0700
Subject: Make EVAL_HASH optional.

---
 src/chess.h    |  2 +-
 src/evalhash.c | 13 ++++++++++---
 src/main.c     |  8 +++++++-
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/chess.h b/src/chess.h
index 8861ef1..e47279d 100755
--- a/src/chess.h
+++ b/src/chess.h
@@ -947,7 +947,7 @@ typedef struct _PLY_INFO
 }
 PLY_INFO;
 
-#define EVAL_HASH
+// #define EVAL_HASH
 #ifdef EVAL_HASH
 #define EVAL_HASH_TABLE_SIZE (2097152) // 32Mb (per thread)
 
diff --git a/src/evalhash.c b/src/evalhash.c
index 210c369..bd95b99 100644
--- a/src/evalhash.c
+++ b/src/evalhash.c
@@ -19,12 +19,11 @@ Revision History:
 --*/
 
 #include "chess.h"
-#ifdef EVAL_HASH
 
 extern ULONG g_uIterateDepth;
 
-SCORE 
-GetRoughEvalScore(IN OUT SEARCHER_THREAD_CONTEXT *ctx, 
+SCORE
+GetRoughEvalScore(IN OUT SEARCHER_THREAD_CONTEXT *ctx,
                   IN SCORE iAlpha,
                   IN SCORE iBeta,
                   IN FLAG fUseHash)
@@ -67,6 +66,7 @@ Return value:
     {
         return Eval(ctx, iAlpha, iBeta);
     }
+#ifdef EVAL_HASH
     else if ((fUseHash) || (ctx->uPly <= (g_uIterateDepth / 2)))
     {
         u64Key = (pos->u64PawnSig ^ pos->u64NonPawnSig);
@@ -93,9 +93,16 @@ Return value:
             }
         }
     }
+#else
+    (void)u64Key;
+    (void)u;
+    (void)fUseHash;
+#endif
     return(pos->iMaterialBalance[pos->uToMove] + ctx->uPositional);
 }
 
+#ifdef EVAL_HASH
+
 
 SCORE
 ProbeEvalHash(IN OUT SEARCHER_THREAD_CONTEXT *ctx, IN SCORE iAlpha, IN SCORE iBeta)
diff --git a/src/main.c b/src/main.c
index 01c8d26..1cf7f91 100755
--- a/src/main.c
+++ b/src/main.c
@@ -79,10 +79,16 @@ Return value:
 #ifdef DUMP_TREE
     Trace("    Search tree dumpfile generation enabled\n");
 #endif
-    Trace("    Hash sizes: %u Mb (main), %u Mb / thread (pawn), %u Mb / thread (eval)\n", 
+#ifdef EVAL_HASH
+    Trace("    Hash sizes: %u Mb (main), %u Mb / thread (pawn), %u Mb / thread (eval)\n",
           (g_uHashTableSizeEntries * sizeof(HASH_ENTRY)) / MB,
           PAWN_HASH_TABLE_SIZE * sizeof(PAWN_HASH_ENTRY) / MB,
           EVAL_HASH_TABLE_SIZE * sizeof(EVAL_HASH_ENTRY) / MB);
+#else
+    Trace("    Hash sizes: %u Mb (main), %u Mb / thread (pawn)\n",
+          (g_uHashTableSizeEntries * sizeof(HASH_ENTRY)) / MB,
+          PAWN_HASH_TABLE_SIZE * sizeof(PAWN_HASH_ENTRY) / MB);
+#endif
     Trace("    QCheckPlies: %u\n", QPLIES_OF_NON_CAPTURE_CHECKS);
     Trace("    FutilityBase: %u\n", FUTILITY_BASE_MARGIN);
     p = ExportEvalDNA();
-- 
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