/*
   *==========================================================================
   *
   *      xyzModem.c
   *
   *      RedBoot stream handler for xyzModem protocol
   *
   *==========================================================================

   * SPDX-License-Identifier:	eCos-2.0

   *==========================================================================
   *#####DESCRIPTIONBEGIN####
   *
   * Author(s):    gthomas
   * Contributors: gthomas, tsmith, Yoshinori Sato
   * Date:         2000-07-14
   * Purpose:
   * Description:
   *
   * This code is part of RedBoot (tm).
   *
   *####DESCRIPTIONEND####
   *
   *==========================================================================
   */

  #include <common.h>
  #include <xyzModem.h>
  #include <stdarg.h>
  #include <crc.h>

  /* Assumption - run xyzModem protocol over the console port */

  /* Values magic to the protocol */

  #define SOH 0x01
  #define STX 0x02
  #define EOT 0x04
  #define ACK 0x06
  #define BSP 0x08
  #define NAK 0x15
  #define CAN 0x18

  #define EOF 0x1A		/* ^Z for DOS officionados */

  /* Data & state local to the protocol */

  static struct
  {

    int *__chan;

    unsigned char pkt[1024], *bufp;
    unsigned char blk, cblk, crc1, crc2;
    unsigned char next_blk;	/* Expected block */
    int len, mode, total_retries;
    int total_SOH, total_STX, total_CAN;
    bool crc_mode, at_eof, tx_ack;

    unsigned long file_length, read_length;

  } xyz;

  #define xyzModem_CHAR_TIMEOUT            2000	/* 2 seconds */

  #define xyzModem_MAX_RETRIES             20
  #define xyzModem_MAX_RETRIES_WITH_CRC    10

  #define xyzModem_CAN_COUNT                3	/* Wait for 3 CAN before quitting */

  typedef int cyg_int32;

  static int

  CYGACC_COMM_IF_GETC_TIMEOUT (char chan, char *c)
  {

  
    ulong now = get_timer(0);
    while (!tstc ())

      {

        if (get_timer(now) > xyzModem_CHAR_TIMEOUT)
          break;

      }
    if (tstc ())
      {
        *c = getc ();
        return 1;
      }
    return 0;

  }

  static void

  CYGACC_COMM_IF_PUTC (char x, char y)
  {
    putc (y);

  }

  /* Validate a hex character */

  __inline__ static bool

  _is_hex (char c)

  {

    return (((c >= '0') && (c <= '9')) ||
  	  ((c >= 'A') && (c <= 'F')) || ((c >= 'a') && (c <= 'f')));

  }

  /* Convert a single hex nibble */

  __inline__ static int

  _from_hex (char c)

  {

    int ret = 0;
  
    if ((c >= '0') && (c <= '9'))
      {
        ret = (c - '0');
      }
    else if ((c >= 'a') && (c <= 'f'))
      {
        ret = (c - 'a' + 0x0a);

      }

    else if ((c >= 'A') && (c <= 'F'))
      {
        ret = (c - 'A' + 0x0A);
      }
    return ret;

  }

  /* Convert a character to lower case */

  __inline__ static char

  _tolower (char c)

  {

    if ((c >= 'A') && (c <= 'Z'))
      {
        c = (c - 'A') + 'a';

      }

    return c;

  }

  /* Parse (scan) a number */

  static bool

  parse_num (char *s, unsigned long *val, char **es, char *delim)

  {

    bool first = true;
    int radix = 10;
    char c;
    unsigned long result = 0;
    int digit;
  
    while (*s == ' ')
      s++;
    while (*s)
      {
        if (first && (s[0] == '0') && (_tolower (s[1]) == 'x'))
  	{
  	  radix = 16;
  	  s += 2;
  	}
        first = false;
        c = *s++;
        if (_is_hex (c) && ((digit = _from_hex (c)) < radix))
  	{
  	  /* Valid digit */

  	  result = (result * radix) + digit;

  	}
        else
  	{
  	  if (delim != (char *) 0)
  	    {
  	      /* See if this character is one of the delimiters */
  	      char *dp = delim;
  	      while (*dp && (c != *dp))
  		dp++;
  	      if (*dp)
  		break;		/* Found a good delimiter */
  	    }
  	  return false;		/* Malformatted number */
  	}

      }

    *val = result;
    if (es != (char **) 0)
      {
        *es = s;

      }

    return true;

  }

  #ifdef DEBUG

  /*
   * Note: this debug setup works by storing the strings in a fixed buffer
   */

  static char zm_debug_buf[8192];
  static char *zm_out = zm_debug_buf;
  static char *zm_out_start = zm_debug_buf;

  static int

  zm_dprintf (char *fmt, ...)

  {

    int len;
    va_list args;

    va_start (args, fmt);
    len = diag_vsprintf (zm_out, fmt, args);
    zm_out += len;
    return len;

  }
  
  static void

  zm_flush (void)

  {

    zm_out = zm_out_start;

  }

  
  static void

  zm_dump_buf (void *buf, int len)

  {

  }
  
  static unsigned char zm_buf[2048];
  static unsigned char *zm_bp;
  
  static void

  zm_new (void)

  {

    zm_bp = zm_buf;

  }
  
  static void

  zm_save (unsigned char c)

  {

    *zm_bp++ = c;

  }
  
  static void

  zm_dump (int line)

  {

    zm_dprintf ("Packet at line: %d
  ", line);
    zm_dump_buf (zm_buf, zm_bp - zm_buf);

  }
  
  #define ZM_DEBUG(x) x
  #else
  #define ZM_DEBUG(x)
  #endif

  /* Wait for the line to go idle */

  static void

  xyzModem_flush (void)

  {

    int res;
    char c;
    while (true)
      {
        res = CYGACC_COMM_IF_GETC_TIMEOUT (*xyz.__chan, &c);
        if (!res)
  	return;

      }
  }
  
  static int

  xyzModem_get_hdr (void)

  {

    char c;
    int res;
    bool hdr_found = false;
    int i, can_total, hdr_chars;
    unsigned short cksum;
  
    ZM_DEBUG (zm_new ());
    /* Find the start of a header */
    can_total = 0;
    hdr_chars = 0;
  
    if (xyz.tx_ack)
      {
        CYGACC_COMM_IF_PUTC (*xyz.__chan, ACK);
        xyz.tx_ack = false;

      }

    while (!hdr_found)
      {
        res = CYGACC_COMM_IF_GETC_TIMEOUT (*xyz.__chan, &c);
        ZM_DEBUG (zm_save (c));
        if (res)
  	{
  	  hdr_chars++;
  	  switch (c)
  	    {
  	    case SOH:
  	      xyz.total_SOH++;
  	    case STX:
  	      if (c == STX)
  		xyz.total_STX++;
  	      hdr_found = true;
  	      break;
  	    case CAN:
  	      xyz.total_CAN++;
  	      ZM_DEBUG (zm_dump (__LINE__));
  	      if (++can_total == xyzModem_CAN_COUNT)
  		{
  		  return xyzModem_cancel;
  		}
  	      else
  		{
  		  /* Wait for multiple CAN to avoid early quits */
  		  break;
  		}
  	    case EOT:
  	      /* EOT only supported if no noise */
  	      if (hdr_chars == 1)
  		{
  		  CYGACC_COMM_IF_PUTC (*xyz.__chan, ACK);
  		  ZM_DEBUG (zm_dprintf ("ACK on EOT #%d
  ", __LINE__));
  		  ZM_DEBUG (zm_dump (__LINE__));
  		  return xyzModem_eof;
  		}
  	    default:
  	      /* Ignore, waiting for start of header */
  	      ;
  	    }
  	}
        else
  	{
  	  /* Data stream timed out */
  	  xyzModem_flush ();	/* Toss any current input */
  	  ZM_DEBUG (zm_dump (__LINE__));
  	  CYGACC_CALL_IF_DELAY_US ((cyg_int32) 250000);
  	  return xyzModem_timeout;
  	}

      }

    /* Header found, now read the data */
    res = CYGACC_COMM_IF_GETC_TIMEOUT (*xyz.__chan, (char *) &xyz.blk);
    ZM_DEBUG (zm_save (xyz.blk));
    if (!res)
      {
        ZM_DEBUG (zm_dump (__LINE__));
        return xyzModem_timeout;

      }

    res = CYGACC_COMM_IF_GETC_TIMEOUT (*xyz.__chan, (char *) &xyz.cblk);
    ZM_DEBUG (zm_save (xyz.cblk));
    if (!res)
      {
        ZM_DEBUG (zm_dump (__LINE__));
        return xyzModem_timeout;

      }

    xyz.len = (c == SOH) ? 128 : 1024;
    xyz.bufp = xyz.pkt;
    for (i = 0; i < xyz.len; i++)
      {
        res = CYGACC_COMM_IF_GETC_TIMEOUT (*xyz.__chan, &c);
        ZM_DEBUG (zm_save (c));
        if (res)
  	{
  	  xyz.pkt[i] = c;
  	}
        else
  	{
  	  ZM_DEBUG (zm_dump (__LINE__));
  	  return xyzModem_timeout;
  	}

      }

    res = CYGACC_COMM_IF_GETC_TIMEOUT (*xyz.__chan, (char *) &xyz.crc1);
    ZM_DEBUG (zm_save (xyz.crc1));
    if (!res)
      {
        ZM_DEBUG (zm_dump (__LINE__));
        return xyzModem_timeout;

      }

    if (xyz.crc_mode)
      {
        res = CYGACC_COMM_IF_GETC_TIMEOUT (*xyz.__chan, (char *) &xyz.crc2);
        ZM_DEBUG (zm_save (xyz.crc2));
        if (!res)
  	{
  	  ZM_DEBUG (zm_dump (__LINE__));
  	  return xyzModem_timeout;
  	}

      }

    ZM_DEBUG (zm_dump (__LINE__));
    /* Validate the message */
    if ((xyz.blk ^ xyz.cblk) != (unsigned char) 0xFF)
      {
        ZM_DEBUG (zm_dprintf
  		("Framing error - blk: %x/%x/%x
  ", xyz.blk, xyz.cblk,
  		 (xyz.blk ^ xyz.cblk)));
        ZM_DEBUG (zm_dump_buf (xyz.pkt, xyz.len));
        xyzModem_flush ();
        return xyzModem_frame;

      }

    /* Verify checksum/CRC */
    if (xyz.crc_mode)
      {

        cksum = crc16_ccitt(0, xyz.pkt, xyz.len);

        if (cksum != ((xyz.crc1 << 8) | xyz.crc2))
  	{
  	  ZM_DEBUG (zm_dprintf ("CRC error - recvd: %02x%02x, computed: %x
  ",
  				xyz.crc1, xyz.crc2, cksum & 0xFFFF));
  	  return xyzModem_cksum;
  	}

      }

    else
      {
        cksum = 0;
        for (i = 0; i < xyz.len; i++)
  	{
  	  cksum += xyz.pkt[i];
  	}
        if (xyz.crc1 != (cksum & 0xFF))
  	{
  	  ZM_DEBUG (zm_dprintf
  		    ("Checksum error - recvd: %x, computed: %x
  ", xyz.crc1,
  		     cksum & 0xFF));
  	  return xyzModem_cksum;
  	}
      }
    /* If we get here, the message passes [structural] muster */
    return 0;

  }

  int

  xyzModem_stream_open (connection_info_t * info, int *err)

  {

    int stat = 0;
    int retries = xyzModem_MAX_RETRIES;
    int crc_retries = xyzModem_MAX_RETRIES_WITH_CRC;

  /*    ZM_DEBUG(zm_out = zm_out_start); */

  #ifdef xyzModem_zmodem

    if (info->mode == xyzModem_zmodem)
      {
        *err = xyzModem_noZmodem;
        return -1;

      }
  #endif

  /* TODO: CHECK ! */

    int dummy = 0;

    xyz.__chan = &dummy;

    xyz.len = 0;
    xyz.crc_mode = true;
    xyz.at_eof = false;
    xyz.tx_ack = false;
    xyz.mode = info->mode;
    xyz.total_retries = 0;
    xyz.total_SOH = 0;
    xyz.total_STX = 0;
    xyz.total_CAN = 0;

    xyz.read_length = 0;
    xyz.file_length = 0;

    CYGACC_COMM_IF_PUTC (*xyz.__chan, (xyz.crc_mode ? 'C' : NAK));

    if (xyz.mode == xyzModem_xmodem)
      {
        /* X-modem doesn't have an information header - exit here */
        xyz.next_blk = 1;
        return 0;

      }

    while (retries-- > 0)
      {
        stat = xyzModem_get_hdr ();
        if (stat == 0)
  	{
  	  /* Y-modem file information header */
  	  if (xyz.blk == 0)
  	    {

  	      /* skip filename */
  	      while (*xyz.bufp++);
  	      /* get the length */
  	      parse_num ((char *) xyz.bufp, &xyz.file_length, NULL, " ");

  	      /* The rest of the file name data block quietly discarded */
  	      xyz.tx_ack = true;
  	    }
  	  xyz.next_blk = 1;
  	  xyz.len = 0;
  	  return 0;
  	}
        else if (stat == xyzModem_timeout)
  	{
  	  if (--crc_retries <= 0)
  	    xyz.crc_mode = false;
  	  CYGACC_CALL_IF_DELAY_US (5 * 100000);	/* Extra delay for startup */
  	  CYGACC_COMM_IF_PUTC (*xyz.__chan, (xyz.crc_mode ? 'C' : NAK));
  	  xyz.total_retries++;
  	  ZM_DEBUG (zm_dprintf ("NAK (%d)
  ", __LINE__));
  	}
        if (stat == xyzModem_cancel)
  	{
  	  break;
  	}

      }

    *err = stat;
    ZM_DEBUG (zm_flush ());
    return -1;

  }

  int

  xyzModem_stream_read (char *buf, int size, int *err)

  {

    int stat, total, len;
    int retries;
  
    total = 0;
    stat = xyzModem_cancel;
    /* Try and get 'size' bytes into the buffer */
    while (!xyz.at_eof && (size > 0))
      {
        if (xyz.len == 0)
  	{
  	  retries = xyzModem_MAX_RETRIES;
  	  while (retries-- > 0)
  	    {
  	      stat = xyzModem_get_hdr ();
  	      if (stat == 0)
  		{
  		  if (xyz.blk == xyz.next_blk)
  		    {
  		      xyz.tx_ack = true;
  		      ZM_DEBUG (zm_dprintf
  				("ACK block %d (%d)
  ", xyz.blk, __LINE__));
  		      xyz.next_blk = (xyz.next_blk + 1) & 0xFF;

  		      if (xyz.mode == xyzModem_xmodem || xyz.file_length == 0)
  			{

  			  /* Data blocks can be padded with ^Z (EOF) characters */
  			  /* This code tries to detect and remove them */
  			  if ((xyz.bufp[xyz.len - 1] == EOF) &&
  			      (xyz.bufp[xyz.len - 2] == EOF) &&
  			      (xyz.bufp[xyz.len - 3] == EOF))
  			    {
  			      while (xyz.len
  				     && (xyz.bufp[xyz.len - 1] == EOF))
  				{
  				  xyz.len--;
  				}
  			    }
  			}

  		      /*
  		       * See if accumulated length exceeds that of the file.
  		       * If so, reduce size (i.e., cut out pad bytes)
  		       * Only do this for Y-modem (and Z-modem should it ever
  		       * be supported since it can fall back to Y-modem mode).
  		       */
  		      if (xyz.mode != xyzModem_xmodem && 0 != xyz.file_length)
  			{
  			  xyz.read_length += xyz.len;
  			  if (xyz.read_length > xyz.file_length)
  			    {
  			      xyz.len -= (xyz.read_length - xyz.file_length);
  			    }
  			}

  		      break;
  		    }
  		  else if (xyz.blk == ((xyz.next_blk - 1) & 0xFF))
  		    {
  		      /* Just re-ACK this so sender will get on with it */
  		      CYGACC_COMM_IF_PUTC (*xyz.__chan, ACK);
  		      continue;	/* Need new header */
  		    }
  		  else
  		    {
  		      stat = xyzModem_sequence;
  		    }
  		}
  	      if (stat == xyzModem_cancel)
  		{
  		  break;
  		}
  	      if (stat == xyzModem_eof)
  		{
  		  CYGACC_COMM_IF_PUTC (*xyz.__chan, ACK);
  		  ZM_DEBUG (zm_dprintf ("ACK (%d)
  ", __LINE__));
  		  if (xyz.mode == xyzModem_ymodem)
  		    {
  		      CYGACC_COMM_IF_PUTC (*xyz.__chan,
  					   (xyz.crc_mode ? 'C' : NAK));
  		      xyz.total_retries++;
  		      ZM_DEBUG (zm_dprintf ("Reading Final Header
  "));
  		      stat = xyzModem_get_hdr ();
  		      CYGACC_COMM_IF_PUTC (*xyz.__chan, ACK);
  		      ZM_DEBUG (zm_dprintf ("FINAL ACK (%d)
  ", __LINE__));
  		    }
  		  xyz.at_eof = true;
  		  break;
  		}
  	      CYGACC_COMM_IF_PUTC (*xyz.__chan, (xyz.crc_mode ? 'C' : NAK));
  	      xyz.total_retries++;
  	      ZM_DEBUG (zm_dprintf ("NAK (%d)
  ", __LINE__));
  	    }
  	  if (stat < 0)
  	    {
  	      *err = stat;
  	      xyz.len = -1;
  	      return total;
  	    }
  	}
        /* Don't "read" data from the EOF protocol package */
        if (!xyz.at_eof)
  	{
  	  len = xyz.len;
  	  if (size < len)
  	    len = size;
  	  memcpy (buf, xyz.bufp, len);
  	  size -= len;
  	  buf += len;
  	  total += len;
  	  xyz.len -= len;
  	  xyz.bufp += len;
  	}

      }

    return total;

  }
  
  void

  xyzModem_stream_close (int *err)

  {

    diag_printf
      ("xyzModem - %s mode, %d(SOH)/%d(STX)/%d(CAN) packets, %d retries
  ",
       xyz.crc_mode ? "CRC" : "Cksum", xyz.total_SOH, xyz.total_STX,
       xyz.total_CAN, xyz.total_retries);
    ZM_DEBUG (zm_flush ());

  }

  /* Need to be able to clean out the input buffer, so have to take the */
  /* getc */

  void
  xyzModem_stream_terminate (bool abort, int (*getc) (void))

  {
    int c;

    if (abort)
      {
        ZM_DEBUG (zm_dprintf ("!!!! TRANSFER ABORT !!!!
  "));
        switch (xyz.mode)
  	{

  	case xyzModem_xmodem:
  	case xyzModem_ymodem:

  	  /* The X/YMODEM Spec seems to suggest that multiple CAN followed by an equal */
  	  /* number of Backspaces is a friendly way to get the other end to abort. */

  	  CYGACC_COMM_IF_PUTC (*xyz.__chan, CAN);
  	  CYGACC_COMM_IF_PUTC (*xyz.__chan, CAN);
  	  CYGACC_COMM_IF_PUTC (*xyz.__chan, CAN);
  	  CYGACC_COMM_IF_PUTC (*xyz.__chan, CAN);
  	  CYGACC_COMM_IF_PUTC (*xyz.__chan, BSP);
  	  CYGACC_COMM_IF_PUTC (*xyz.__chan, BSP);
  	  CYGACC_COMM_IF_PUTC (*xyz.__chan, BSP);
  	  CYGACC_COMM_IF_PUTC (*xyz.__chan, BSP);

  	  /* Now consume the rest of what's waiting on the line. */

  	  ZM_DEBUG (zm_dprintf ("Flushing serial line.
  "));
  	  xyzModem_flush ();
  	  xyz.at_eof = true;
  	  break;

  #ifdef xyzModem_zmodem
  	case xyzModem_zmodem:

  	  /* Might support it some day I suppose. */

  #endif

  	  break;
  	}
      }
    else
      {
        ZM_DEBUG (zm_dprintf ("Engaging cleanup mode...
  "));

        /*
         * Consume any trailing crap left in the inbuffer from

         * previous received blocks. Since very few files are an exact multiple

         * of the transfer block size, there will almost always be some gunk here.
         * If we don't eat it now, RedBoot will think the user typed it.
         */

        ZM_DEBUG (zm_dprintf ("Trailing gunk:
  "));

        while ((c = (*getc) ()) > -1)
          ;

        ZM_DEBUG (zm_dprintf ("
  "));

        /*
         * Make a small delay to give terminal programs like minicom
         * time to get control again after their file transfer program
         * exits.
         */

        CYGACC_CALL_IF_DELAY_US ((cyg_int32) 250000);
      }

  }
  
  char *

  xyzModem_error (int err)

  {

    switch (err)
      {

      case xyzModem_access:

        return "Can't access file";
        break;

      case xyzModem_noZmodem:

        return "Sorry, zModem not available yet";
        break;

      case xyzModem_timeout:

        return "Timed out";
        break;

      case xyzModem_eof:

        return "End of file";
        break;

      case xyzModem_cancel:

        return "Cancelled";
        break;

      case xyzModem_frame:

        return "Invalid framing";
        break;

      case xyzModem_cksum:

        return "CRC/checksum error";
        break;

      case xyzModem_sequence:

        return "Block sequence error";
        break;

      default:

        return "Unknown error";
        break;

      }
  }

  /*
   * RedBoot interface
   */