1 files changed, 51 insertions, 0 deletions
diff --git a/src/searchsup.c b/src/searchsup.c
index 37eca66..9a2cc50 100644
--- a/src/searchsup.c
+++ b/src/searchsup.c
@@ -270,6 +270,57 @@ ComputeMoveScore(IN SEARCHER_THREAD_CONTEXT *ctx,
 }
 
 
+SCORE
+GetCheckSee(IN SEARCHER_THREAD_CONTEXT *ctx,
+            IN MOVE mv,
+            IN ULONG uMoveNum)
+/**
+
+Routine description:
+
+    SEE for a checking move, used by ComputeMoveExtension's callers
+    (Search, HelpSearch, and eventually QSearch) to decide how much to
+    extend/reduce a check. Must be computed on the PRE-move position --
+    see.c's exchange walk needs the piece still sitting on cFrom.
+
+    Move generation/scoring (_ScoreAllMoves, _ScoreAllEscapes in
+    generate.c) already runs a real SEE on this same (pos, mv) pair
+    whenever it scores an ambiguous capture or promotion, and stashes
+    the sign in the move's MVF_SEE_KNOWN/MVF_SEE_NONNEGATIVE flags.
+    Reuse that instead of walking the exchange (GetAttacks()) again.
+    Only the sign matters to any caller of ComputeMoveExtension, so the
+    cached value is coarsened to 0/-1.
+
+Parameters:
+
+    SEARCHER_THREAD_CONTEXT *ctx : searcher thread context
+    MOVE mv : the checking move
+    ULONG uMoveNum : mv's index in ctx->sMoveStack.mvf[], or (ULONG)-1
+        if mv did not come from the move stack (e.g. the hash move)
+
+Return value:
+
+    SCORE
+
+**/
+{
+    BITV bvFlags;
+
+    ASSERT(IS_CHECKING_MOVE(mv));
+    if (uMoveNum != (ULONG)-1)
+    {
+        ASSERT(uMoveNum < MAX_MOVE_STACK);
+        ASSERT(IS_SAME_MOVE(mv, ctx->sMoveStack.mvf[uMoveNum].mv));
+        bvFlags = ctx->sMoveStack.mvf[uMoveNum].bvFlags;
+        if (bvFlags & MVF_SEE_KNOWN)
+        {
+            return((bvFlags & MVF_SEE_NONNEGATIVE) ? 0 : -1);
+        }
+    }
+    return(SEE(&ctx->sPosition, mv));
+}
+
+
 void
 ComputeMoveExtension(IN SEARCHER_THREAD_CONTEXT *ctx,
                      IN SCORE iAlpha,