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feat: implemented TT for move ordering
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,142 @@ | ||
| use brogle_core::{Move, ZobristKey}; | ||
|
|
||
| #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash, Default)] | ||
| pub enum NodeType { | ||
| /// The score is exact | ||
| #[default] | ||
| Pv, | ||
| /// The score is less than alpha (upper bound) | ||
| All, | ||
| /// The score is greater than or equal to beta (lower bound) | ||
| Cut, | ||
| } | ||
|
|
||
| impl NodeType { | ||
| pub fn new(score: i32, alpha: i32, beta: i32) -> Self { | ||
| if score <= alpha { | ||
| Self::All | ||
| } else if score >= beta { | ||
| Self::Cut | ||
| } else { | ||
| Self::Pv | ||
| } | ||
| } | ||
| } | ||
|
|
||
| #[derive(PartialEq, Eq, Clone, Debug, Hash, Default)] | ||
| pub struct TTableEntry { | ||
| pub(crate) key: ZobristKey, | ||
| pub(crate) depth: u32, | ||
| pub(crate) bestmove: Move, | ||
| pub(crate) score: i32, | ||
| pub(crate) flag: NodeType, | ||
| pub(crate) age: usize, | ||
| } | ||
|
|
||
| impl TTableEntry { | ||
| pub fn new(key: ZobristKey, bestmove: Move, score: i32, depth: u32, flag: NodeType) -> Self { | ||
| Self { | ||
| key, | ||
| bestmove, | ||
| score, | ||
| depth, | ||
| flag, | ||
| age: 0, | ||
| } | ||
| } | ||
| } | ||
|
|
||
| /// Default size of the Transposition Table, in bytes | ||
| const DEFAULT_TTABLE_SIZE: usize = 1_048_576; // 1 mb | ||
|
|
||
| #[derive(Debug)] | ||
| pub struct TTable(pub Vec<Option<TTableEntry>>); | ||
|
|
||
| impl TTable { | ||
| /// Create a new [`TTable`] that is `size` bytes. | ||
| /// | ||
| /// Its size will be `size_of::<TTableEntry>() * capacity` | ||
| pub fn new(size: usize) -> Self { | ||
| Self::from_capacity(size / size_of::<TTableEntry>()) | ||
| } | ||
|
|
||
| /// Create a new [`TTable`] that can hold `capacity` entries. | ||
| pub fn from_capacity(capacity: usize) -> Self { | ||
| Self(vec![None; capacity]) | ||
| } | ||
|
|
||
| pub fn index(&self, key: &ZobristKey) -> usize { | ||
| // TODO: Enforce size as a power of two so you can use & instead of % | ||
| key.inner() as usize % self.0.len() | ||
| } | ||
|
|
||
| /// Get the entry, without regards for whether it matches the provided key | ||
| fn get_entry(&self, key: &ZobristKey) -> Option<&TTableEntry> { | ||
| // We can safely index as we've initialized this ttable to be non-empty | ||
| self.0[self.index(key)].as_ref() | ||
| } | ||
|
|
||
| /// Mutably get the entry, without regards for whether it matches the provided key | ||
| fn get_entry_mut(&mut self, key: &ZobristKey) -> Option<&mut TTableEntry> { | ||
| let index = self.index(key); | ||
| self.0[index].as_mut() | ||
| } | ||
|
|
||
| /// Get the entry if and only if it matches the provided key | ||
| pub fn get(&self, key: &ZobristKey) -> Option<&TTableEntry> { | ||
| if let Some(entry) = self.get_entry(key) { | ||
| if &entry.key == key { | ||
| return Some(entry); | ||
| } | ||
| } | ||
| None | ||
| } | ||
|
|
||
| pub fn get_mut(&mut self, key: &ZobristKey) -> Option<&mut TTableEntry> { | ||
| if let Some(entry) = self.get_entry_mut(key) { | ||
| if &entry.key == key { | ||
| return Some(entry); | ||
| } | ||
| } | ||
| None | ||
| } | ||
|
|
||
| pub fn update_flag(&mut self, key: &ZobristKey, flag: NodeType) { | ||
| if let Some(entry) = self.get_mut(key) { | ||
| entry.flag = flag; | ||
| } | ||
| } | ||
|
|
||
| pub fn update_score(&mut self, key: &ZobristKey, new_score: i32) { | ||
| if let Some(entry) = self.get_mut(key) { | ||
| entry.score = new_score; | ||
| } | ||
| } | ||
|
|
||
| /// Store `entry` in the table at `entry.key`, overriding whatever was there. | ||
| pub fn store(&mut self, entry: TTableEntry) { | ||
| self.insert(entry); | ||
| } | ||
|
|
||
| /// Store `entry` in the table at `entry.key`, if the existing entry at `entry.key` is either `None` or has a lower `depth` than `entry`. | ||
| pub fn store_if_greater_depth(&mut self, entry: TTableEntry) { | ||
| if self | ||
| .get(&entry.key) | ||
| .is_some_and(|old_entry| old_entry.depth < entry.depth) | ||
| { | ||
| self.store(entry); | ||
| } | ||
| } | ||
|
|
||
| /// Inserts `entry` in the table at `entry.key`, overriding whatever was there and returning a mutable reference to it. | ||
| pub fn insert(&mut self, entry: TTableEntry) -> &mut TTableEntry { | ||
| let index = self.index(&entry.key); | ||
| self.0[index].insert(entry) | ||
| } | ||
| } | ||
|
|
||
| impl Default for TTable { | ||
| fn default() -> Self { | ||
| Self::new(DEFAULT_TTABLE_SIZE) | ||
| } | ||
| } |
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