SSFC_BASE64_ENCODE 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 SSFC_BASE64_ENCODE into the relevant SAP transaction such as SE37 or SE80.
CALL FUNCTION 'SSFC_BASE64_ENCODE' " EXPORTING bindata = " xstring Binary Data * binleng = " i IMPORTING b64data = " string EXCEPTIONS SSF_KRN_ERROR = 1 " SSF_KRN_NOOP = 2 " SSF_KRN_NOMEMORY = 3 " Main Memory Not Sufficient SSF_KRN_OPINV = 4 " SSF_KRN_INPUT_DATA_ERROR = 5 " SSF_KRN_INVALID_PAR = 6 " An SSF Parameter is Erroneous SSF_KRN_INVALID_PARLEN = 7 " Length of an SSF Parameter is Erroneous . " SSFC_BASE64_ENCODE