uchar: Introduce C11 uchar.h

Currently this implementation only supports UTF-32

headers/posix/uchar.h

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2018 Haiku, Inc. All Right Reserved
+ * Distributed under the terms of MIT license.
+ */
+#ifndef _UCHAR_H
+#define _UCHAR_H
+
+#include <wchar.h>
+
+#ifdef __cplusplus
+extern "C" {
+#else
+typedef wchar_t char32_t; /* our wchar_t is utf32 */
+typedef wchar_t char16_t;
+#endif
+
+#define __STD_UTF_32__ 1
+
+/* We don't define __STD_UTF_16__, so the format of char16_t is unspecified */
+static __inline size_t
+c16rtomb(char *dest, char16_t wc, mbstate_t *mbState)
+{
+	return wcrtomb(dest, wc, mbState);
+}
+static __inline size_t
+mbrtoc16(char16_t *dest, const char *src, size_t srcLength, mbstate_t *mbState)
+{
+	return mbrtowc(dest, src, srcLength, mbState);
+}
+
+static __inline size_t
+c32rtomb(char *dest, char32_t wc, mbstate_t *mbState)
+{
+	return wcrtomb(dest, wc, mbState);
+}
+static __inline size_t
+mbrtoc32(char32_t *dest, const char *src, size_t srcLength, mbstate_t *mbState)
+{
+	return mbrtowc(dest, src, srcLength, mbState);
+}
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* _UCHAR_H */