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use crate::moves::Move;
use super::Grossmeister;
/// https://www.chessprogramming.org/Node_Types
#[derive(Debug, PartialEq, Clone, Copy)]
pub enum NodeType {
/// Principal variation node - exact score
PV,
/// Fail-high
Cut,
/// Fail-low
All,
}
#[derive(Debug, PartialEq, Clone, Copy)]
pub struct TranspositionTableItem {
/// Zobrist hash of this position
pub hash: u64,
pub mov: Move,
pub depth: u8,
pub score: f32,
pub node_type: NodeType,
}
pub const TTABLE_SIZE: u64 = 2u64.pow(24);
pub type TranspositionTable = Vec<Option<TranspositionTableItem>>;
impl Grossmeister {
/// Find current transposition in Transposition Table
pub fn transposition(&self) -> Option<TranspositionTableItem> {
match self.transposition_table[(self.board.hash % TTABLE_SIZE) as usize] {
Some(item) => {
if item.hash == self.board.hash {
return Some(item)
}
None
}
None => None
}
}
}
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