base64 encoding

[Kamikaze47]

Was bored, so I figured i would give this a shot.

Untested, so try at your own risk

STRING_LENGTH   CON 24 ; Must be divisable by 3

in_string       VAR BYTE[STRING_LENGTH]
in_byte         VAR BYTE         
in_bit          VAR BYTE
b64_string      VAR BYTE[STRING_LENGTH*4/3]
b64_byte        VAR BYTE
b64_bit         VAR BYTE
temp            VAR BYTE

in_byte=0                                               ; Start at byte 0
in_bit=7                                                ; Most significant bit first

FOR b64_byte=0 TO (STRING_LENGTH*4/3)-1                 ; For each base64 byte:
    b64_string[b64_byte]=0                              ; Clear the byte
    FOR b64_bit=5 TO 0 STEP -1                          ; For each bit 5 thru 0:
        temp=in_string[in_byte]                         ; Get the current input byte
        temp=temp >> in_bit                             ; Shift to get the current bit as bit 0
        temp=temp & 1                                   ; Clear the other bits
        temp=temp << b64_bit                            ; Shift to the correct output bit position
        b64_string[b64_byte]=temp|b64_string[b64_byte]  ; Add the bit to the base64 byte
        in_bit=in_bit-1                                 ; Next less significant bit
        IF in_bit=255 THEN                              ; If we past bit 0:
            in_bit=7                                    ; Set to bit 7 of the next byte
            in_byte=in_byte+1
        ENDIF
    NEXT b64_bit
    SELECT CASE b64_string[b64_byte]                    ; Convert to base64 coded ASCII
        CASE IS<=25                                     ; 0-25
            b64_string[b64_byte]=b64_string[b64_byte]+65; "A"-"Z"
        CASE IS<=51                                     ; 26-51
            b64_string[b64_byte]=b64_string[b64_byte]+71; "a"-"z"
        CASE IS<=61                                     ; 52-61
            b64_string[b64_byte]=b64_string[b64_byte]-4 ; "0"-"9"
        CASE 62                                         ; 62
            b64_string[b64_byte]=43                     ; "+"
        CASE 63                                         ; 63
            b64_string[b64_byte]=47                     ; "/"
    END SELECT
NEXT b64_byte