From 67d91dfd505ce7e2c641c12e5d14b50896874ec7 Mon Sep 17 00:00:00 2001 From: Marco Costalba Date: Sat, 7 Jul 2012 19:30:27 +0100 Subject: [PATCH] Use last_1() to compute new TT size Transposition table consists of a power of 2 number of TTCluster entries. No functional change. Signed-off-by: Marco Costalba --- src/tt.cpp | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/src/tt.cpp b/src/tt.cpp index 09a74d2d..72952257 100644 --- a/src/tt.cpp +++ b/src/tt.cpp @@ -20,6 +20,7 @@ #include #include +#include "bitboard.h" #include "tt.h" TranspositionTable TT; // Our global transposition table @@ -37,18 +38,13 @@ TranspositionTable::~TranspositionTable() { /// TranspositionTable::set_size() sets the size of the transposition table, -/// measured in megabytes. +/// measured in megabytes. Transposition table consists of a power of 2 number of +/// TTCluster and each cluster consists of ClusterSize number of TTEntries. Each +/// non-empty entry contains information of exactly one position. void TranspositionTable::set_size(size_t mbSize) { - size_t newSize = 1024; - - // Transposition table consists of clusters and each cluster consists - // of ClusterSize number of TTEntries. Each non-empty entry contains - // information of exactly one position and newSize is the number of - // clusters we are going to allocate. - while (2ULL * newSize * sizeof(TTCluster) <= (mbSize << 20)) - newSize *= 2; + size_t newSize = 1ULL << last_1((mbSize << 20) / sizeof(TTCluster)); if (newSize == size) return; @@ -56,13 +52,15 @@ void TranspositionTable::set_size(size_t mbSize) { size = newSize; delete [] entries; entries = new (std::nothrow) TTCluster[size]; + if (!entries) { std::cerr << "Failed to allocate " << mbSize << "MB for transposition table." << std::endl; exit(EXIT_FAILURE); } - clear(); + + clear(); // operator new is not guaranteed to initialize memory to zero } -- 2.39.2