From afd6ec94da33896b0b6626cf5595c2631c07bcfc Mon Sep 17 00:00:00 2001
From: Marcus Holland-Moritz <github@mhxnet.de>
Date: Wed, 6 Aug 2025 14:14:16 +0200
Subject: [PATCH] fix(fits_categorizer): support `get_unused_lsb_count` for
 big-endian

---
 src/writer/categorizer/fits_categorizer.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/writer/categorizer/fits_categorizer.cpp b/src/writer/categorizer/fits_categorizer.cpp
index 332e2b75..0d52c125 100644
--- a/src/writer/categorizer/fits_categorizer.cpp
+++ b/src/writer/categorizer/fits_categorizer.cpp
@@ -124,7 +124,10 @@ T fold_left_bit_or(std::span<uint8_t const> data) {
 
 template <>
 unsigned get_unused_lsb_count<uint16_t>(std::span<uint8_t const> imagedata) {
-  static constexpr uint64_t const kLsbMask{UINT64_C(0x0100010001000100)};
+  static constexpr uint64_t const kLsbMask{std::endian::native ==
+                                                   std::endian::little
+                                               ? UINT64_C(0x0100010001000100)
+                                               : UINT64_C(0x0001000100010001)};
   static constexpr size_t const kAlignment{64}; // for AVX512
 
   uint16_t b16{0};