pppchar.c

在ARM7和UC/OSII的平台上实现了GPS自动报站的功能,涉及GPS模块LEA_4S的驱动,位置速寻算法,语音芯片ISD4004的录放音驱动,LED页面管理等等.从启动代码到操作系统的移植以及到业

      if (pkt->nb_plen < (PPP_HDRLEN + PPP_FCS_LEN)) 
      {
         if(pkt->nb_plen)
         {
          //  ConPrintf("ppp_inchar: ppp:%p short pkt (%d)\n", mppp, pkt->nb_plen);
            mppp->io_errors++;
            pkt->nb_plen = 0;
         }
         return;
      }
      /* Fall to here if we have received a complete error free packet.
       * unlink packet for inpkt and pass to packet input routine 
       */
      pkt = mppp->inpkt;
      mppp->inpkt = NULL;     /* clear inpkt */
      /* reset prot pointer to the beginning of the received data after
       * the two AC bytes 
       */
      pkt->nb_prot = pkt->nb_buff + MaxLnh + 2;    /* 2 is for A/C bytes */
      pkt->nb_plen -= 4;      /* ALL_STATIONS + UI + ??? */
      pkt->net = mppp->ifp;

#ifdef PPP_MULTILINK
      pkt->link = mppp;    /* save received link */
#endif

#ifdef LB_XOVER
      putq(&ppp_rcvdq, (qp)pkt);	/* put pkt in input queue */
      SignalPPPDemux();			/* wake demuxer */
#else /* not LB_XOVER */
      ppp_inpkt(mppp, pkt);
#endif
      return;
   }

   if (mppp->sc_flags & SC_FLUSH)
   {
      flushed++;
      return;
   }

   if (c == PPP_ESCAPE)
   {   
      mppp->sc_flags |= SC_ESCAPED;
      return;
   }

   /* If this character value should be escaped (per our asyncmap) then 
    * assume we have received a control code and punt it.
    */
   if ((c < 0x20) && (mppp->my_asyncmap & (1L << c)))
      return;

   if (mppp->sc_flags & SC_ESCAPED) 
   {   
      mppp->sc_flags &= ~SC_ESCAPED;
      c ^= PPP_TRANS;
   }

   /*
    * Initialize buffer on first octet received.
    * First octet could be address, or protocol when compressing
    * address/control bytes away.
    * Second octet is control.
    * Third octet is first or second (when compressing protocol)
    * octet of protocol.
    * Fourth octet is second octet of protocol.
    */
   if(pkt->nb_plen == 0)
   {
      mppp->sc_fcs = PPP_INITFCS;
      if (c != PPP_ALLSTATIONS) 
      {
         if (mppp->sc_flags & SC_REJ_COMP_AC) 
         {
            //ConPrintf("ppp %p: missing ALLSTATIONS, got 0x%x; flags %x\n",
               //mppp, c, mppp->sc_flags);
            goto flush;
         }
         /* Stuff the missing compressed bytes into the inbuf */
         *(u_char*)pkt->nb_prot++ = PPP_ALLSTATIONS;
         *pkt->nb_prot++ = PPP_UI;
         pkt->nb_plen = 2;
      }
   }

   if ((pkt->nb_plen == 1) && (c != PPP_UI))
   {
      //ConPrintf("ppp %p: missing UI, got 0x%x\n", mppp, c);
      goto flush;
   }

   if ((pkt->nb_plen == 2) && ((c & 1) == 1) )
   {
      /* RFC1331 says we have to accept a compressed protocol */
      *pkt->nb_prot++ = (u_char)0;  /* insert the zero that was compressed out */
      pkt->nb_plen++;
      /* code below will put the lower protocol byte after it */
   }

   *pkt->nb_prot++ = (u_char)c;
   pkt->nb_plen++;
   mppp->sc_fcs = PPP_FCS(mppp->sc_fcs, c);
   return;

flush:
   mppp->io_errors++;
   mppp->sc_flags |= SC_FLUSH;
   /* drop any partially filled data packets. */
   if(mppp->inpkt && (mppp->inpkt->nb_plen > 0))
   {
      LOCK_NET_RESOURCE(FREEQ_RESID);
      pk_free(mppp->inpkt);
      UNLOCK_NET_RESOURCE(FREEQ_RESID);
      mppp->inpkt = NULL;
   }
   return;
}

/* FUNCTION: ppp_sendchars()
 * 
 * Send all the bytes in a packet. This includes HDLC stuffing and PPP header
 * compression. (Note - not VJ compression).
 *
 * PARAM1: M_PPP mppp
 * PARAM2: PACKET pkt
 *
 * RETURNS: 
 */

int
ppp_sendchars(M_PPP mppp, PACKET pkt)
{
   int      i;
   int      err;
   u_char   c;
   u_short  protocol;
   u_short  fcs;
   u_short  testfcs;
   u_char   hdlc_hdr[4];
   int      hdlc_len;


   /* first 16 bits of data should be PPP protocl (LCP, IPCP, etc.) Get 
    * This value so we can make compression decisions. 
    */
   protocol = ppp_getshort((u_char*)pkt->nb_prot);	      

   /* bump pkt past protocol field */
   pkt->nb_prot += 2;
   pkt->nb_plen -= 2;

   fcs = PPP_INITFCS;
   /* Send addess/control (AC). See if we can "compress" it. */
   if((!mppp->lcp_gotoptions.neg_accompression) ||
      (protocol == PPP_LCP))
   {
      /* Can't compress AC away; put A/C bytes in hdr buf. */
      hdlc_hdr[0] = PPP_ALLSTATIONS;   
      hdlc_hdr[1] = PPP_UI;
      hdlc_len = 2;
   }
   else
      hdlc_len = 0;     /* compressed AC bytes away */

   if((!mppp->lcp_gotoptions.neg_pcompression) ||
      (protocol >= 0x100))
   {
      /* Can't compress protocol to one byte; need to send high byte too. */
      hdlc_hdr[hdlc_len++] =  (u_char)(protocol >> 8);
   }

   /* load low byte of protocol */
   hdlc_hdr[hdlc_len++] =  (u_char)(protocol  & 0xFF);

   /* hdlc header is now prepared, prepend it to pkt data */
   pkt->nb_prot -= hdlc_len;
   pkt->nb_plen += hdlc_len;
#ifdef NPDEBUG
   if(pkt->nb_prot < pkt->nb_buff)
      panic("pppchar prepend");
#endif
   MEMCPY(pkt->nb_prot, hdlc_hdr, hdlc_len);

   /* send a PPP flag byte to "reset" the other guy's line state. We test 
    * The result of each ln_putc call and return if error. 
    */
   err = mppp->line.ln_putc(&mppp->line, PPP_FLAG);
   if(err)
   {
      //ConPrintf("ppp: ln_putc error %d on link %p\n", err, mppp);
      goto ppp_putc_err;
   }

   /* loop through the chars in the packet buffer, encoding and sending
    * as we go.
    */
   for(i = 0; i < (int)pkt->nb_plen; i++)
   {
      c = (u_char)*(pkt->nb_prot + i);
      fcs = PPP_FCS(fcs, c);     /* Update FCS for each byte */

      if (ESCAPE_P(c))
      {
         mppp->line.ln_putc(&mppp->line, PPP_ESCAPE);
         err = mppp->line.ln_putc(&mppp->line, (u_char)(c ^ PPP_TRANS));
      } 
      else     /* no escape needed, just send & test */
      {
         err = mppp->line.ln_putc(&mppp->line, c);
      }
      if (err)
      {
         mppp->io_errors++;
         goto ppp_putc_err;
      }
   }

   /* End of sending pkt data, Send FCS value. We have to "escape" encode 
    * these bytes too. 
    */
   
   c = (u_char)(~fcs & 0xFF);
   if (ESCAPE_P(c)) 
   {
      err = mppp->line.ln_putc(&mppp->line, PPP_ESCAPE);
      err = mppp->line.ln_putc(&mppp->line, (c ^ PPP_TRANS));
   } 
   else 
   {
      err = mppp->line.ln_putc(&mppp->line, c);
   }
   testfcs = PPP_FCS(fcs, c);


   c = (u_char)((~fcs >> 8) & 0xFF);
   if (ESCAPE_P(c)) 
   {
      err = mppp->line.ln_putc(&mppp->line, PPP_ESCAPE);
      err = mppp->line.ln_putc(&mppp->line, (c ^ PPP_TRANS));
   }
   else 
   {
      err = mppp->line.ln_putc(&mppp->line, c);
   }
   testfcs = PPP_FCS(testfcs, c);
#ifdef NPDEBUG    /* sanity check our FCS logic */
   if (testfcs !=  PPP_GOODFCS)
      ;//ConPrintf("fcs not ok ??\n");
#endif

   /* send a final PPP flag for end of packet */
   mppp->line.ln_putc(&mppp->line, PPP_FLAG);

ppp_putc_err:
   
   LOCK_NET_RESOURCE(FREEQ_RESID);
   pk_free(pkt);
   UNLOCK_NET_RESOURCE(FREEQ_RESID);
   return err;
}

#endif   /* PPP_CHARIO - whole file can be ifdeffed out */
#endif   /* USE_PPP - whole file can be ifdeffed out */