SC_DC_FERROR
(ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
ppp->rstate |= SC_DC_FERROR;
ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);