From: joergoster <osterj165@googlemail.com>
Date: Mon, 27 Jan 2020 17:53:25 +0000 (+0100)
Subject: Simplify hashfull calculation.
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=a910ba71eedde4f67805f05b29215cbeff4fe5f1

Simplify hashfull calculation.

We can simplify the calculation of the hashfull info by looping over exact 1,000 entries,
and then divide the result by ClusterSize. Somewhat memory accesses, somewhat more accurate.

Passed non-regression LTC
https://tests.stockfishchess.org/tests/view/5e30079dab2d69d58394fd5d
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 30125 W: 3987 L: 3926 D: 22212
Ptnml(0-2): 177, 2504, 9558, 2642, 141

closes https://github.com/official-stockfish/Stockfish/pull/2523

No functional change.
---

diff --git a/src/tt.cpp b/src/tt.cpp
index 080d3a6b..46860fe9 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -148,9 +148,9 @@ TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
 int TranspositionTable::hashfull() const {
 
   int cnt = 0;
-  for (int i = 0; i < 1000 / ClusterSize; ++i)
+  for (int i = 0; i < 1000; ++i)
       for (int j = 0; j < ClusterSize; ++j)
           cnt += (table[i].entry[j].genBound8 & 0xF8) == generation8;
 
-  return cnt * 1000 / (ClusterSize * (1000 / ClusterSize));
+  return cnt / ClusterSize;
 }