From 752150107e178159785202cb2371a3f368d791b6 Mon Sep 17 00:00:00 2001
From: Paul-Nicolas Madelaine <pnm@pnm.tf>
Date: Wed, 22 Oct 2025 22:59:53 +0200
Subject: [PATCH] update move generation for pinned pieces

---
 src/position.rs | 37 +++++++++++++++++++------------------
 1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/src/position.rs b/src/position.rs
index d060e97..590c975 100644
--- a/src/position.rs
+++ b/src/position.rs
@@ -1054,10 +1054,13 @@ impl Position {
         }
 
         let blockers_x_ray = blockers & !(x | y);
-        let pinned = (d.bishop(king_square, blockers_x_ray) & theirs.bishop()
-            | d.rook(king_square, blockers_x_ray) & theirs.rook())
-        .map(|sq| d.segment(king_square, sq))
-        .reduce_or();
+        let pinned_diagonally = (d.bishop(king_square, blockers_x_ray) & theirs.bishop())
+            .map(|sq| d.segment(king_square, sq))
+            .reduce_or();
+        let pinned_horizontally = (d.rook(king_square, blockers_x_ray) & theirs.rook())
+            .map(|sq| d.segment(king_square, sq))
+            .reduce_or();
+        let pinned = pinned_diagonally | pinned_horizontally;
 
         let checker = checkers.first();
         let block_check = checker
@@ -1223,30 +1226,28 @@ impl Position {
 
         // pinned pieces
         {
-            let aux = |visitor: &mut T, role| {
-                for from in global_mask_from & *ours.get(role) & pinned {
+            let aux = |visitor: &mut T, role, mask| {
+                for from in global_mask_from & *ours.get(role) & mask {
                     visitor.moves(
-                        (global_mask_to
-                            & d.targets(role, from, blockers)
-                            & !us
-                            & d.line(king_square, from))
-                        .map(|to| RawMove {
-                            kind: MoveType::PieceMove,
-                            from,
-                            to,
-                            role,
+                        (global_mask_to & !us & pinned & d.line(king_square, from)).map(|to| {
+                            RawMove {
+                                kind: MoveType::PieceMove,
+                                from,
+                                to,
+                                role,
+                            }
                         }),
                     )
                 }
             };
             if visitor.roles(Role::Bishop) {
-                aux(visitor, Role::Bishop)
+                aux(visitor, Role::Bishop, pinned_diagonally);
             }
             if visitor.roles(Role::Rook) {
-                aux(visitor, Role::Rook)
+                aux(visitor, Role::Rook, pinned_horizontally);
             }
             if visitor.roles(Role::Queen) {
-                aux(visitor, Role::Queen)
+                aux(visitor, Role::Queen, pinned);
             }
         }
     }