/EM></TT><BR /></DIV><P>Returns the MAC (<EM>digest</EM>) computed by <EM>hmac</EM> thus far.
The internal state of <EM>hmac</EM> is not modified; this feature makes it
possible to compute a "rolling MAC" of a document.  The length of <EM>digest</EM> is determined by the <A HREF="#digest-length" STYLE="symbol">digest-length</A> of <EM>digest-name</EM>
passed to <A HREF="#make-hmac" STYLE="symbol">make-hmac</A> when <EM>hmac</EM> was constructed.</P><P>If <EM>buffer</EM> is provided, the computed MAC will be