unicode_to_gbk
n = unicode_to_gbk(unidx, gbkcode, *outbuf, *outbytesleft, &uconv_num_internal);
n = unicode_to_gbk(unidx, gbkcode, *outbuf, *outbytesleft, &uconv_num_internal);
int unicode_to_gbk(int unidx, unsigned long gbkcode, char* buf, size_t buflen, int *uconv_num);