_CONTROLCHR OFF



test$ = "abc"

a$ = B256to128$(test$)

b$ = B128to256$(a$)

PRINT test$, a$, b$

PRINT LEN(test$), LEN(a$), LEN(b$)



SLEEP



FOR i = 0 TO 255

    t$ = CHR$(i)

    PRINT i, t$,

    a$ = B256to128(t$)

    PRINT a$,

    b$ = B128to256(a$)

    PRINT b$

    IF t$ <> b$ THEN

        PRINT "DON'T MATCH!!"

        END

    END IF

NEXT



PRINT

PRINT "All characters match before and after encoding and decoding."







FUNCTION B256to128$ (text$)

    FOR i = 1 TO LEN(text$)

        a = ASC(text$, i) '                      get the ASCII value of our character

        b$ = RIGHT$("00000000" + _BIN$(a), 8) '  convert it to binary

        temp$ = temp$ + b$ '                      add the binary to a single long string

    NEXT

    padding$ = STRING$(7 - LEN(temp$) MOD 7, "0")

    temp$ = temp$ + padding$ '                    add necessay padding to make it suitable for base-128 encoding

    FOR i = 1 TO LEN(temp$) STEP 7

        c$ = MID$(temp$, i, 7) '                  get 7 characters from our 8 byte represention

        c = VAL("&B" + c$) '                      that's the character value of our base 128-character

        temp1$ = temp1$ + CHR$(c + 65) '              add that to our new string

    NEXT

    B256to128$ = temp1$

END FUNCTION



FUNCTION B128to256$ (text$)

    FOR i = 1 TO LEN(text$)

        a = ASC(text$, i) - 65

        b$ = RIGHT$("0000000" + _BIN$(a), 7)

        temp$ = temp$ + b$

    NEXT

    temp$ = LEFT$(temp$, 8 * INT(LEN(temp$) / 8)) 'remove padding

    FOR i = 1 TO LEN(temp$) STEP 8

        b$ = "&B" + MID$(temp$, i, 8)

        temp1$ = temp1$ + CHR$(VAL(b$))

    NEXT

    B128to256$ = temp1$

END FUNCTION