add vterm

lisp/vterm/utf8.h

@@ -0,0 +1,12 @@
+#ifndef UTF8_H
+#define UTF8_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+size_t codepoint_to_utf8(const uint32_t codepoint, unsigned char buffer[4]);
+bool utf8_to_codepoint(const unsigned char buffer[4], const size_t len,
+                       uint32_t *codepoint);
+
+#endif /* UTF8_H */