(
    ; Create a table of strings
    (sym TXT r7)
    (def T_HELLO 0)
    (def T_UNK 1)
    (mkbf TXT)
    (mkbfv r0 "*** Type ascii to uppercase. Press q to quit. ***\n")
    (bfins @TXT T_HELLO r0)
    (mkbfv r0 "🐈")
    (bfins @TXT T_UNK r0)

    ; Print string from the table
    (bfrd r0 @TXT T_HELLO)
    (call print r0)

    (proc print str
        ; Print string from a buffer
        (sym ch r1) (sym pos r2)
        (ld pos 0)
        (:next)
            (bfrd ch @str pos)
            (ret.ov)
            (ld @stdout ch)
            (inc pos)
        (j :next)
    )

    (:loop)
        (ld r0 @stdin)

        (cmp r0 'q'
            (eq? (ld @stdout '\n')
                 (halt)))

        ; uppercase ASCII
        (cmp r0 'a' (<? (j :badchar)))
        (cmp r0 'z' (>? (j :badchar)))
        (sub r0 ' ')
        (ld @stdout r0)
    (j :loop)

    (:badchar)
        (ld @stdout r0)
        (bfrd r0 @TXT T_UNK)
        (call print r0)
    (j :loop)
)