From e4ce92a24fb0cc49de909acef504c94a743f11ac Mon Sep 17 00:00:00 2001
From: Eduard Valeyev <eduard@valeyev.net>
Date: Thu, 5 Dec 2024 17:40:27 -0500
Subject: [PATCH] enforce_bc: handle multiple displacements

---
 src/madness/mra/mraimpl.h | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/src/madness/mra/mraimpl.h b/src/madness/mra/mraimpl.h
index e24b4ac0198..9d92fd40541 100644
--- a/src/madness/mra/mraimpl.h
+++ b/src/madness/mra/mraimpl.h
@@ -3217,20 +3217,23 @@ template <typename T, std::size_t NDIM>
 
 
     static inline bool enforce_bc(bool is_periodic, Level n, Translation& l) {
-        Translation two2n = 1ul << n;
-        if (l < 0) {
-            if (is_periodic)
-                l += two2n; // Periodic BC
-            else
-                return false; // Zero BC
-        }
-        else if (l >= two2n) {
-            if (is_periodic)
-                l -= two2n; // Periodic BC
-            else
-                return false; // Zero BC
-        }
-        return true;
+      const Translation two2n = 1ul << n;
+      if (l < 0) {
+        if (is_periodic) {
+          do {
+            l += two2n; // Periodic BC
+          } while (l < 0);
+        } else
+          return false; // Zero BC
+      } else if (l >= two2n) {
+        if (is_periodic) {
+          do {
+            l -= two2n; // Periodic BC
+          } while (l >= two2n);
+        } else
+          return false; // Zero BC
+      }
+      return true;
     }
 
     static inline bool enforce_in_volume(Level n, Translation& l) {