1 files changed, 35 insertions, 0 deletions
diff --git a/libc/src/stdlib/wctomb.cpp b/libc/src/stdlib/wctomb.cpp
new file mode 100644
index 000000000000..0ca1a84cd923
--- /dev/null
+++ b/libc/src/stdlib/wctomb.cpp
@@ -0,0 +1,35 @@
+//===-- Implementation of wctomb ------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/stdlib/wctomb.h"
+
+#include "hdr/types/wchar_t.h"
+#include "src/__support/common.h"
+#include "src/__support/libc_errno.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/wchar/mbstate.h"
+#include "src/__support/wchar/wcrtomb.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(int, wctomb, (char *s, wchar_t wc)) {
+  static internal::mbstate internal_mbstate;
+  if (s == nullptr)
+    return 0;
+
+  auto result = internal::wcrtomb(s, wc, &internal_mbstate);
+
+  if (!result.has_value()) { // invalid wide character
+    libc_errno = EILSEQ;
+    return -1;
+  }
+
+  return static_cast<int>(result.value());
+}
+
+} // namespace LIBC_NAMESPACE_DECL