DFRC Support (#33)

Bench: 2726116

monty-core/src/consts.rs

@@ -42,33 +42,8 @@ impl Right {
     pub const WKS: u8 = 0b0100;
     pub const BQS: u8 = 0b0010;
     pub const BKS: u8 = 0b0001;
-    pub const TABLE: [[u8; 2]; 2] = [[Self::WQS, Self::WKS], [Self::BQS, Self::BKS]];
 }
 
-// paths required to be clear for castling
-pub struct Path;
-impl Path {
-    pub const BD1: u64 = 0x0000_0000_0000_000E;
-    pub const FG1: u64 = 0x0000_0000_0000_0060;
-    pub const BD8: u64 = 0x0E00_0000_0000_0000;
-    pub const FG8: u64 = 0x6000_0000_0000_0000;
-    pub const TABLE: [[u64; 2]; 2] = [[Self::BD1, Self::FG1], [Self::BD8, Self::FG8]];
-}
-
-// the castling rook move bitboards
-pub const ROOK_MOVES: [[(u8, u8); 2]; 2] = [[(0, 3), (56, 59)], [(7, 5), (63, 61)]];
-
-// mask off castling rights by square
-pub const CASTLE_MASK: [u8; 64] = init!(|idx, 64| match idx {
-    0 => 7,
-    4 => 3,
-    7 => 11,
-    56 => 13,
-    60 => 12,
-    63 => 14,
-    _ => 15,
-});
-
 // for promotions / double pushes
 pub struct Rank;
 impl Rank {

monty-core/src/frc.rs

@@ -0,0 +1,89 @@
+use crate::{
+    consts::{Piece, Right, Side},
+    position::Position,
+};
+
+#[derive(Clone, Copy)]
+pub struct Castling {
+    chess960: bool,
+    castle_mask: [u8; 64],
+    rook_files: [[u8; 2]; 2],
+}
+
+impl Default for Castling {
+    fn default() -> Self {
+        Self {
+            chess960: false,
+            castle_mask: [0; 64],
+            rook_files: [[0; 2]; 2],
+        }
+    }
+}
+
+impl Castling {
+    pub fn is_chess960(&self) -> bool {
+        self.chess960
+    }
+
+    pub fn mask(&self, sq: usize) -> u8 {
+        self.castle_mask[sq]
+    }
+
+    pub fn rook_file(&self, side: usize, ks: usize) -> u8 {
+        self.rook_files[side][ks]
+    }
+
+    pub fn parse(&mut self, pos: &Position, rights_str: &str) -> u8 {
+        let mut kings = [4, 4];
+
+        self.chess960 = false;
+        self.rook_files[0][0] = 0;
+        self.rook_files[0][1] = 7;
+        self.rook_files[1][0] = 0;
+        self.rook_files[1][1] = 7;
+
+        let rights = rights_str.chars().fold(0, |cr, ch| {
+            cr | match ch as u8 {
+                b'Q' => Right::WQS,
+                b'K' => Right::WKS,
+                b'q' => Right::BQS,
+                b'k' => Right::BKS,
+                b'A'..=b'H' => self.parse_castle(pos, Side::WHITE, &mut kings, ch),
+                b'a'..=b'h' => self.parse_castle(pos, Side::BLACK, &mut kings, ch),
+                _ => 0,
+            }
+        });
+
+        for sq in self.castle_mask.iter_mut() {
+            *sq = 15;
+        }
+
+        self.castle_mask[usize::from(self.rook_file(0, 0))] = 7;
+        self.castle_mask[usize::from(self.rook_file(0, 1))] = 11;
+        self.castle_mask[usize::from(self.rook_file(1, 0)) + 56] = 13;
+        self.castle_mask[usize::from(self.rook_file(1, 1)) + 56] = 14;
+        self.castle_mask[kings[0]] = 3;
+        self.castle_mask[kings[1] + 56] = 12;
+
+        rights
+    }
+
+    fn parse_castle(
+        &mut self,
+        pos: &Position,
+        side: usize,
+        kings: &mut [usize; 2],
+        ch: char,
+    ) -> u8 {
+        self.chess960 = true;
+
+        let wkc = (pos.piece(side) & pos.piece(Piece::KING)).trailing_zeros() as u8 & 7;
+        kings[side] = wkc as usize;
+        let rook = ch as u8 - [b'A', b'a'][side];
+        let i = usize::from(rook > wkc);
+
+        self.rook_files[side][i] = rook;
+
+        [[Right::WQS, Right::WKS], [Right::BQS, Right::BKS]][side][i]
+    }
+}

monty-core/src/lib.rs

@@ -1,11 +1,13 @@
 mod attacks;
 mod consts;
+mod frc;
 mod moves;
 mod policy;
 mod position;
 mod value;
 
 pub use consts::{Flag, Piece, Side};
+pub use frc::Castling;
 pub use moves::{Move, MoveList};
 pub use policy::{PolicyNetwork, POLICY_NETWORK, SubNet};
 pub use position::{perft, GameState, Position};

monty-core/src/moves.rs

@@ -1,4 +1,4 @@
-use crate::{consts::Flag, position::Position, PolicyNetwork};
+use crate::{consts::Flag, frc::Castling, position::Position, PolicyNetwork};
 
 #[macro_export]
 macro_rules! pop_lsb {
@@ -101,15 +101,22 @@ impl Move {
         }
     }
 
-    #[must_use]
-    pub fn to_uci(self) -> String {
+    pub fn to_uci(self, castling: &Castling) -> String {
         let idx_to_sq = |i| format!("{}{}", ((i & 7) + b'a') as char, (i / 8) + 1);
         let promo = if self.flag & 0b1000 > 0 {
             ["n", "b", "r", "q"][(self.flag & 0b11) as usize]
         } else {
             ""
         };
-        format!("{}{}{}", idx_to_sq(self.from), idx_to_sq(self.to), promo)
+
+        let to = if castling.is_chess960() && [Flag::QS, Flag::KS].contains(&self.flag) {
+            let sf = 56 * (self.to / 56);
+            sf + castling.rook_file(usize::from(sf > 0), usize::from(self.flag == Flag::KS))
+        } else {
+            self.to
+        };
+
+        format!("{}{}{}", idx_to_sq(self.from), idx_to_sq(to), promo)
     }
 }