From e27e18e482bad6de666be5f77e6feb181d5fdfa9 Mon Sep 17 00:00:00 2001
From: dogeystamp <dogeystamp@disroot.org>
Date: Sat, 28 Dec 2024 21:33:29 -0500
Subject: [PATCH] tune: repetition history set to 100 plies

---
 src/lib.rs | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 03d1bb3..637c1df 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -516,9 +516,8 @@ mod ringptr_tests {
 
 /// Ring-buffer of previously seen hashes, used to avoid draw by repetition.
 ///
-/// Only stores at most `HISTORY_SIZE` plies, since most cases of repetition happen recently.
-/// Technically, it should be 100 plies because of the 50-move rule.
-#[derive(Default, Clone, Copy, Debug)]
+/// Only stores at most `HISTORY_SIZE` plies.
+#[derive(Clone, Copy, Debug)]
 struct BoardHistory {
     hashes: [Zobrist; HISTORY_SIZE],
     /// Index of the start of the history in the buffer
@@ -527,6 +526,17 @@ struct BoardHistory {
     ptr_end: RingPtr<HISTORY_SIZE>,
 }
 
+impl Default for BoardHistory {
+    fn default() -> Self {
+        BoardHistory {
+            // rust can't derive this
+            hashes: [Zobrist::default(); HISTORY_SIZE],
+            ptr_start: Default::default(),
+            ptr_end: Default::default(),
+        }
+    }
+}
+
 impl PartialEq for BoardHistory {
     /// Always equal, since comparing two boards with different histories shouldn't matter.
     fn eq(&self, _other: &Self) -> bool {
@@ -539,7 +549,7 @@ impl Eq for BoardHistory {}
 /// Size in plies of the board history.
 ///
 /// Actual capacity is one less than this.
-const HISTORY_SIZE: usize = 15;
+const HISTORY_SIZE: usize = 100;
 
 impl BoardHistory {
     /// Counts occurences of this hash in the history.