Add magic mask generation

src/movegen/mod.rs

@@ -8,3 +8,6 @@ mod king;
 mod knight;
 mod pawn;
 mod rook;
+
+// Magic bitboard generation
+mod wizardry;

src/movegen/wizardry/mask.rs

@@ -0,0 +1,39 @@
+use crate::board::{Bitboard, File, Rank, Square};
+use crate::movegen::bishop::bishop_moves;
+use crate::movegen::rook::rook_moves;
+
+#[allow(unused)] // FIXME: remove once used
+pub fn generate_bishop_mask(square: Square) -> Bitboard {
+    let rays = bishop_moves(square, Bitboard::EMPTY);
+
+    let mask = File::A.into_bitboard()
+        | File::H.into_bitboard()
+        | Rank::First.into_bitboard()
+        | Rank::Eighth.into_bitboard();
+
+    rays - mask
+}
+
+#[allow(unused)] // FIXME: remove once used
+pub fn generate_rook_mask(square: Square) -> Bitboard {
+    let rays = rook_moves(square, Bitboard::EMPTY);
+
+    let mask = {
+        let mut mask = Bitboard::EMPTY;
+        if square.file() != File::A {
+            mask = mask | File::A.into_bitboard()
+        };
+        if square.file() != File::H {
+            mask = mask | File::H.into_bitboard()
+        };
+        if square.rank() != Rank::First {
+            mask = mask | Rank::First.into_bitboard()
+        };
+        if square.rank() != Rank::Eighth {
+            mask = mask | Rank::Eighth.into_bitboard()
+        };
+        mask
+    };
+
+    rays - mask
+}

src/movegen/wizardry/mod.rs

@@ -0,0 +1 @@
+mod mask;