--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/zint/backend/gs1.h	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,50 @@
+/* gs1.h - Verifies GS1 data */
+/*
+    libzint - the open source barcode library
+    Copyright (C) 2009-2022 Robin Stuart <rstuart114@gmail.com>
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions
+    are met:
+
+    1. Redistributions of source code must retain the above copyright
+       notice, this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright
+       notice, this list of conditions and the following disclaimer in the
+       documentation and/or other materials provided with the distribution.
+    3. Neither the name of the project nor the names of its contributors
+       may be used to endorse or promote products derived from this software
+       without specific prior written permission.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+    ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+    ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
+    FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+    DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+    OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+    HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+    OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+    SUCH DAMAGE.
+ */
+/* SPDX-License-Identifier: BSD-3-Clause */
+
+#ifndef Z_GS1_H
+#define Z_GS1_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+INTERNAL int gs1_verify(struct zint_symbol *symbol, const unsigned char source[], const int src_len,
+                unsigned char reduced[]);
+INTERNAL char gs1_check_digit(const unsigned char source[], const int src_len);
+INTERNAL int gs1_iso3166_alpha2(const unsigned char *cc);
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+/* vim: set ts=4 sw=4 et : */
+#endif /* Z_GS1_H */