原创 XModem C语言

 return 0;

}

static void flushinput(void)

{

 //while
(port_inbyte(((DLY_1S)*3)>>1)
>= 0)

  ;

}

int xmodemReceive(unsigned char *dest, int destsz)

{

 unsigned char xbuff[1030];

 unsigned char *p;

 int bufsz, crc = 0;

 unsigned char trychar = 'C';

 unsigned char packetno = 1;

 int i, c, len = 0;

 int retry, retrans = MAXRETRANS;

 for(;;)

 {

  for( retry = 0; retry
< 16; ++retry)

  {

   if
(trychar)

    port_outbyte(trychar);


   c =
port_inbyte((DLY_1S)<<1);

   if
(last_error == 0)

   {

    switch
(c)

    {


     case
SOH:

      bufsz
= 128;

      goto
start_recv;

     case
STX:

      bufsz
= 1024;

      goto
start_recv;

     case
EOT:

      flushinput();


      port_outbyte(ACK);


      return
len;

     case
CAN:

      c
= port_inbyte(DLY_1S);

      if
(c == CAN)

      {


       flushinput();


       port_outbyte(ACK);


       return
-1;

      }


      break;


     default:


      break;


    }


   }

  }

  if (trychar == 'C')

  {

   trychar =
NAK;

   continue;


  }

  flushinput();

  port_outbyte(CAN);

  port_outbyte(CAN);

  port_outbyte(CAN);

  return -2;

 start_recv:

  if (trychar == 'C') crc =
1;

  trychar = 0;

  p = xbuff;

  *p++ = c;

  for (i = 0;  i
< (bufsz+(crc?1:0)+3); ++i)

  {

   c =
port_inbyte(DLY_1S);

   if
(last_error != 0)

    goto
reject;

   *p++ =
c;

  }

  if (xbuff[1] == (unsigned
char)(~xbuff[2]) &&

   (xbuff[1] ==
packetno || xbuff[1] == (unsigned char)packetno-1)
&&

   check(crc,
&xbuff[3], bufsz))

  {

   if (xbuff[1]
== packetno) 

   {

    int
count = destsz - len;

    if
(count > bufsz)

     count
= bufsz;

    if
(count > 0)

    {


     memcpy
(&dest[len], &xbuff[3],
count);

     len
+= count;

    }


    ++packetno;


    retrans
= MAXRETRANS+1;

   }

   if (--retrans
<= 0)

   {

    flushinput();


    port_outbyte(CAN);


    port_outbyte(CAN);


    port_outbyte(CAN);


    return
-3;

   }

   port_outbyte(ACK);


   continue;


  }

 reject:

  flushinput();

  port_outbyte(NAK);

 }

}

int xmodemTransmit(unsigned char *src, int srcsz)

{

 unsigned char xbuff[1030];

 int bufsz, crc = -1;

 unsigned char packetno = 1;

 int i, c, len = 0;

 int retry;

 for(;;) {

  for( retry = 0; retry
< 16; ++retry)

  {

   c =
port_inbyte((DLY_1S)<<1);

   if
(last_error == 0)

   {

    switch
(c)

    {


     case
'C':

      crc
= 1;

      goto
start_trans;

     case
NAK:

      crc
= 0;

      goto
start_trans;

     case
CAN:

      c
= port_inbyte(DLY_1S);

      if
(c == CAN)

      {


       port_outbyte(ACK);


       flushinput();


       return
-1;

      }


      break;


     default:


      break;


    }


   }

  }

  port_outbyte(CAN);

  port_outbyte(CAN);

  port_outbyte(CAN);

  flushinput();

  return -2;

 for(;;)

  {

  start_trans:

   xbuff[0] =
SOH; bufsz = 128;

   xbuff[1] =
packetno;

   xbuff[2] =
~packetno;

   c = srcsz -
len;

   if (c
> bufsz) c = bufsz;

   if (c
>= 0)

   {

    memset
(&xbuff[3], 0, bufsz);

    if
(c == 0)

    {


     xbuff[3]
= CTRLZ;

    }


    else


    {


     memcpy
(&xbuff[3], &src[len], c);

     if
(c < bufsz) xbuff[3+c] = CTRLZ;

    }


    if
(crc)

    {


     unsigned
short ccrc = crc16_ccitt(&xbuff[3], bufsz);

     xbuff[bufsz+3]
= (ccrc>>8) &
0xFF;

     xbuff[bufsz+4]
= ccrc & 0xFF;

    }


    else


    {


     unsigned
char ccks = 0;

     for
(i = 3; i < bufsz+3; ++i)

     {


      ccks
+= xbuff;

     }


     xbuff[bufsz+3]
= ccks;

    }


    for
(retry = 0; retry < MAXRETRANS; ++retry)

    {


     for
(i = 0; i < bufsz+4+(crc?1:0); ++i)

     {


      port_outbyte(xbuff);


     }


     c
= port_inbyte(DLY_1S);

     if
(last_error == 0 )

     {


      switch
(c)

      {


       case
ACK:

        ++packetno;


        len
+= bufsz;

        goto
start_trans;

       case
CAN:

        c
= port_inbyte(DLY_1S);

        if
( c == CAN)