XPSE

 {$Cleq}
Declare S$
Cls
S$="TEST THE FASTEST XPROFAN"
Print S$+"."
Print ReverseString$(S$)+"."
Waitkey
End

Proc ReverseString$

    Parameters s$

    AsmStart _rstr

        Parameters Addr(s$), Len(s$)
        mov ebx,para1
        mov ecx,para2
        mov edx,para1
        add edx,ecx
        dec edx

        .while edx > ebx

            mov al,[ebx]
            xchg al,[edx]
            mov [ebx],al
            inc ebx
            dec edx

        .endw

    AsmEnd

    Return s$

ENDPROC