Apd |IV |utf8_distance |U8 *a|U8 *b
Apd |U8* |utf8_hop |U8 *s|I32 off
ApMd |U8* |utf8_to_bytes |U8 *s|STRLEN *len
+ApMd |U8* |bytes_from_utf8|U8 *s|STRLEN *len|bool *is_utf8
ApMd |U8* |bytes_to_utf8 |U8 *s|STRLEN *len
Apd |UV |utf8_to_uv_simple|U8 *s|STRLEN* retlen
Adp |UV |utf8_to_uv |U8 *s|STRLEN curlen|STRLEN* retlen|U32 flags