RkCvtZen - convert ASCII characters and single-width katakana to double-width characters
int RkCvtZen(dst, maxdst, src, srclen)
unsigned char *dst;
unsigned char *src;
RkCvtZen converts the srclen bytes of ASCII character and single-width katakana data to double-width character, starting at the area src. A null character in src is not interpreted as the end of the string. The conversion result is stored in the area dst. Characters that are not subject to conversion are copied as they area. The conversion result is truncated to adjust to character boundaries in the EUC code when its byte length exceeds maxdst -1. dst is padded with null characters at the end if possible. EUC code is used to represent both src and dst.
NULL can be specified in dst. NULL overrides the entire conversion result.
This function returns the byte length of the conversion result, or returns 0 if the value of maxdst is invalid.