From 080ac7bd97edf0f9266360bce21c37c4eeb943ed Mon Sep 17 00:00:00 2001
From: Timo Kreuzer <timo.kreuzer@reactos.org>
Date: Mon, 4 Aug 2025 17:40:27 +0300
Subject: [PATCH] [LIBCNTPR] Implement NT version of towupper

---
 sdk/lib/crt/string/ctype.c       |  2 ++
 sdk/lib/crt/string/string.cmake  |  1 +
 sdk/lib/crt/string/towupper_nt.c | 20 ++++++++++++++++++++
 3 files changed, 23 insertions(+)
 create mode 100644 sdk/lib/crt/string/towupper_nt.c

diff --git a/sdk/lib/crt/string/ctype.c b/sdk/lib/crt/string/ctype.c
index 053bce17a03..7da531f7901 100644
--- a/sdk/lib/crt/string/ctype.c
+++ b/sdk/lib/crt/string/ctype.c
@@ -895,6 +895,7 @@ wint_t __cdecl towlower(wint_t c)
    return(c);
 }
 
+#ifndef _LIBCNT_
 /*
  * @implemented
  */
@@ -904,5 +905,6 @@ wint_t __cdecl towupper(wint_t c)
       return (c + upalpha);
    return(c);
 }
+#endif /* _LIBCNT_ */
 
 /* EOF */
diff --git a/sdk/lib/crt/string/string.cmake b/sdk/lib/crt/string/string.cmake
index e7e95c8a1b6..3a80ab7938d 100644
--- a/sdk/lib/crt/string/string.cmake
+++ b/sdk/lib/crt/string/string.cmake
@@ -112,6 +112,7 @@ list(APPEND CRT_STRING_ASM_SOURCE
 
 list(APPEND LIBCNTPR_STRING_SOURCE
     string/mbstowcs_nt.c
+    string/towupper_nt.c
     string/wcstombs_nt.c
 )
 
diff --git a/sdk/lib/crt/string/towupper_nt.c b/sdk/lib/crt/string/towupper_nt.c
new file mode 100644
index 00000000000..4b85e7a01fc
--- /dev/null
+++ b/sdk/lib/crt/string/towupper_nt.c
@@ -0,0 +1,20 @@
+/*
+ * PROJECT:     ReactOS NT CRT library
+ * LICENSE:     MIT (https://spdx.org/licenses/MIT)
+ * PURPOSE:     Implementation of towupper
+ * COPYRIGHT:   Copyright 2025 Timo Kreuzer <timo.kreuzer@reactos.org>
+ */
+
+#define WIN32_NO_STATUS
+#include <windef.h>
+#include <ndk/rtlfuncs.h>
+
+_Check_return_
+_CRTIMP
+wint_t
+__cdecl
+towupper(
+    _In_ wint_t _C)
+{
+    return RtlUpcaseUnicodeChar((WCHAR)_C);
+}