From 2c0cd95ecf0c20b58da89022e293a0ea0476d666 Mon Sep 17 00:00:00 2001 From: Marco Costalba Date: Mon, 30 Mar 2009 09:09:27 +0100 Subject: [PATCH 1/1] An VALUE_TYPE_EVAL score cannot overwrite an entry If we want to store a value of type VALUE_TYPE_EVAL for a given position and we found an already exsisting entry for the same position then we skip. We don't want to overwrite a more valuable score with a lesser one. Note that also in case the exsisting entry is of VALUE_TYPE_EVAL type the overwrite is unuseful because we would store the same score again. Signed-off-by: Marco Costalba --- src/tt.cpp | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/src/tt.cpp b/src/tt.cpp index d7b3b7d5..82d967ca 100644 --- a/src/tt.cpp +++ b/src/tt.cpp @@ -101,7 +101,8 @@ void TranspositionTable::clear() { /// the least valuable of the four entries in a cluster. A TTEntry t1 is /// considered to be more valuable than a TTEntry t2 if t1 is from the /// current search and t2 is from a previous search, or if the depth of t1 -/// is bigger than the depth of t2. +/// is bigger than the depth of t2. A TTEntry of type VALUE_TYPE_EVAL +/// never replaces another entry for the same position. TTEntry* TranspositionTable::store(const Position &pos, Value v, Depth d, Move m, ValueType type) { @@ -112,6 +113,11 @@ TTEntry* TranspositionTable::store(const Position &pos, Value v, Depth d, { if (!tte->key() || tte->key() == pos.get_key()) // empty or overwrite old { + // Do not overwrite position entry when VALUE_TYPE_EVAL + if ( tte->key() + && type == VALUE_TYPE_EVAL) + return NULL; + if (m == MOVE_NONE) m = tte->move(); -- 2.39.2