From: Marco Costalba Date: Tue, 18 Oct 2011 10:24:47 +0000 (+0200) Subject: Better document mate and stalemate detection X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=8f7d36a85dda6e6611d1ee66ceb69949feb8513e Better document mate and stalemate detection In particular add that we can have an harmless false positive in case StopRequest or thread.cutoff_occurred() are set. Reported by David Lee. No functional change. Signed-off-by: Marco Costalba --- diff --git a/src/search.cpp b/src/search.cpp index c163e8ea..438a01be 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -1244,9 +1244,11 @@ split_point_start: // At split points actual search starts from here } // Step 20. Check for mate and stalemate - // All legal moves have been searched and if there are - // no legal moves, it must be mate or stalemate. - // If one move was excluded return fail low score. + // All legal moves have been searched and if there are no legal moves, it + // must be mate or stalemate. Note that we can have a false positive in + // case of StopRequest or thread.cutoff_occurred() are set, but this is + // harmless because return value is discarded anyhow in the parent nodes. + // If we are in a singular extension search then return a fail low score. if (!SpNode && !moveCount) return excludedMove ? oldAlpha : inCheck ? value_mated_in(ss->ply) : VALUE_DRAW;