Rewire GetMoveFailHighPercentage: index by (cFrom, cTo, pMoved) instead

of (cFrom, cTo, color), and expose sample size.

MOVE_TO_INDEX (used elsewhere for the counter-move table) folds any
two moves with the same from/to/color into one fail-high bucket --
e.g. a king shuffle and a queen sac to the same square/color shared
a slot. New MOVE_TO_FH_INDEX uses the low 20 bits of mv.uMove
(cFrom+cTo+pMoved), which already encodes color in pMoved's low bit,
so this is strictly more granular for free. Table grown 0x20000 ->
0x100000 entries to match. Also adds an optional ULONG *puAttempts
out-param so future callers can weight by sample confidence instead
of trusting a percentage computed from as few as one observation.

GetLMRReduction (proto-LMR, live at HEAD) is the only real consumer
right now; verified against head_reference at sd10 across
ecm_ringers/ecm_confident_quick/ecm_hard_quick: net +2 solves (88 vs
87 on confident_quick, 18 vs 17 on hard_quick), node counts flat
within noise (-1.5%/+1.4%/+0.5%).

1 files changed, 1 insertions, 1 deletions

diff --git a/src/chess.h b/src/chess.h
index 3a78b2b..9722414 100755
--- a/src/chess.h
+++ b/src/chess.h
@@ -2782,7 +2782,7 @@ TestBitboards(void);
 extern ULONG g_HistoryCounters[14][128];
 
 ULONG
-GetMoveFailHighPercentage(MOVE mv);
+GetMoveFailHighPercentage(MOVE mv, ULONG *puAttempts);
 
 void
 UpdateDynamicMoveOrdering(SEARCHER_THREAD_CONTEXT *ctx,