From 04178bd86eab3b23b5cb5962cc5be7dfa59fff17 Mon Sep 17 00:00:00 2001
From: Pedro Maciel <Pedro.Maciel@ecmwf.int>
Date: Mon, 11 Mar 2024 16:57:44 +0000
Subject: [PATCH] MIR-650 Exception terminates mir-get-data: HEALPix nested
 ordering with N=1

---
 src/mir/reorder/HEALPix.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/mir/reorder/HEALPix.cc b/src/mir/reorder/HEALPix.cc
index 5898d3897..b6215c1d9 100644
--- a/src/mir/reorder/HEALPix.cc
+++ b/src/mir/reorder/HEALPix.cc
@@ -185,8 +185,8 @@ int HEALPixReorder::ring_to_nest(int r) const {
             p -= 8 * Nside_;
         }
 
-        int i = (r + p) >> 1;
-        int j = (r - p) >> 1;
+        int i = std::max(0, (r + p)) >> 1;
+        int j = std::max(0, (r - p)) >> 1;
 
         ASSERT(f < 12 && i < Nside_ && j < Nside_);
         return CodecFijNest::fij_to_nest(f, i, j, k_);