MySQL 5.7 Release Notes
If you want to add support for a new character set named
MYSET that includes multibyte
characters, you must use multibyte character functions in the
ctype-
source file in the MYSET.cstrings directory.
The existing character sets provide the best documentation and
examples to show how these functions are implemented. Look at
the ctype-*.c files in the
strings directory, such as the files for
the euc_kr, gb2312,
gbk, sjis, and
ujis character sets. Take a look at the
MY_CHARSET_HANDLER structures to see how they
are used. See also the CHARSET_INFO.txt
file in the strings directory for
additional information.