HR_KR_XSTRING_TO_STRING is a standard SAP function module available within R/3 SAP systems depending on your version and release level. Below are the pattern details for this FM showing its interface including any import, export parameters etc and for your convenience any standard documentation available. All this information and more can be viewed if you enter the function module name HR_KR_XSTRING_TO_STRING into the relevant SAP transaction such as SE37 or SE80.
CALL FUNCTION 'HR_KR_XSTRING_TO_STRING' "Convert encoded string to unicode string EXPORTING from_codepage = '8500' " abap_encoding Code page of source encoded string in_xstring = " xstring Source encoded string * out_len = " i Length of source encoded string IMPORTING out_string = " string Output string in unicode . " HR_KR_XSTRING_TO_STRING