23 lines
797 B
Rust
23 lines
797 B
Rust
use crate::board::Bitboard;
|
|
|
|
/// A type representing the magic board indexing a given [Square].
|
|
#[allow(unused)] // FIXME: remove once used
|
|
pub struct Magic {
|
|
/// Magic number.
|
|
pub(crate) magic: u64,
|
|
/// Base offset into the magic square table.
|
|
pub(crate) offset: usize,
|
|
/// Mask to apply to the blocker board before applying the magic.
|
|
pub(crate) mask: Bitboard,
|
|
/// Length of the resulting mask after applying the magic.
|
|
pub(crate) shift: u8,
|
|
}
|
|
|
|
impl Magic {
|
|
#[allow(unused)] // FIXME: remove once used
|
|
pub fn get_index(&self, blockers: Bitboard) -> usize {
|
|
let relevant_occupancy = (blockers & self.mask).0;
|
|
let base_index = ((relevant_occupancy.wrapping_mul(self.magic)) >> self.shift) as usize;
|
|
base_index + self.offset
|
|
}
|
|
}
|