From d500f525f7a416a4f03f97f39e02b2d50373e469 Mon Sep 17 00:00:00 2001
From: Paul-Nicolas Madelaine <pnm@pnm.tf>
Date: Wed, 5 Nov 2025 23:47:00 +0100
Subject: [PATCH] update move generation for pinned pieces

---
 src/lookup.rs   | 24 ++++++++++++++++++++++++
 src/position.rs | 21 +++++++++------------
 2 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/src/lookup.rs b/src/lookup.rs
index 64c7c13..26eeba6 100644
--- a/src/lookup.rs
+++ b/src/lookup.rs
@@ -136,6 +136,22 @@ static LINES: BySquare<BySquare<Bitboard>> = by_square!(a, BySquare([Bitboard(0)
     })
 });
 
+static BISHOP_LINES: BySquare<Bitboard> = by_square!(sq, Bitboard(0), {
+    let mut res = 0;
+    loop_bishop_directions!(d, {
+        res |= RAYS.get(sq).get(d).0;
+    });
+    Bitboard(res)
+});
+
+static ROOK_LINES: BySquare<Bitboard> = by_square!(sq, Bitboard(0), {
+    let mut res = 0;
+    loop_rook_directions!(d, {
+        res |= RAYS.get(sq).get(d).0;
+    });
+    Bitboard(res)
+});
+
 static SEGMENTS: BySquare<BySquare<Bitboard>> = by_square!(a, BySquare([Bitboard(0); 64]), {
     by_square!(b, Bitboard(0), {
         let mut res = 0;
@@ -240,6 +256,14 @@ pub(crate) fn line(a: Square, b: Square) -> Bitboard {
     *LINES.get(a).get(b)
 }
 #[inline]
+pub(crate) fn bishop_lines(square: Square) -> Bitboard {
+    *BISHOP_LINES.get(square)
+}
+#[inline]
+pub(crate) fn rook_lines(square: Square) -> Bitboard {
+    *ROOK_LINES.get(square)
+}
+#[inline]
 pub(crate) fn segment(a: Square, b: Square) -> Bitboard {
     *SEGMENTS.get(a).get(b)
 }
diff --git a/src/position.rs b/src/position.rs
index 1b4fd3e..d86ed63 100644
--- a/src/position.rs
+++ b/src/position.rs
@@ -995,13 +995,10 @@ impl Position {
         }
 
         let blockers_x_ray = blockers & !(x | y);
-        let pinned_diagonally = (lookup::bishop(king_square, blockers_x_ray) & theirs.bishop())
-            .map(|sq| lookup::segment(king_square, sq))
-            .reduce_or();
-        let pinned_horizontally = (lookup::rook(king_square, blockers_x_ray) & theirs.rook())
-            .map(|sq| lookup::segment(king_square, sq))
-            .reduce_or();
-        let pinned = pinned_diagonally | pinned_horizontally;
+        let pinned = ((lookup::bishop(king_square, blockers_x_ray) & theirs.bishop())
+            | (lookup::rook(king_square, blockers_x_ray) & theirs.rook()))
+        .map(|sq| lookup::segment(king_square, sq))
+        .reduce_or();
 
         let checker = checkers.first();
         let block_check = checker
@@ -1173,8 +1170,8 @@ impl Position {
 
         // pinned pieces
         {
-            let aux = |moves: &mut T, role, mask| {
-                for from in global_mask_from & *ours.get(role) & mask {
+            let aux = |moves: &mut T, role, role_mask| {
+                for from in global_mask_from & pinned & role_mask & *ours.get(role) {
                     moves.extend(
                         (global_mask_to & !us & pinned & lookup::line(king_square, from)).map(
                             |to| RawMove {
@@ -1188,13 +1185,13 @@ impl Position {
                 }
             };
             if moves.roles(Role::Bishop) {
-                aux(moves, Role::Bishop, pinned_diagonally);
+                aux(moves, Role::Bishop, lookup::bishop_lines(king_square));
             }
             if moves.roles(Role::Rook) {
-                aux(moves, Role::Rook, pinned_horizontally);
+                aux(moves, Role::Rook, lookup::rook_lines(king_square));
             }
             if moves.roles(Role::Queen) {
-                aux(moves, Role::Queen, pinned);
+                aux(moves, Role::Queen, !Bitboard::new());
             }
         }
     }