bool cmd_pending (void)
{
    static uint8_t xdata len = 0;
    static uint8_t xdata cb[ CMD_BUFF_SIZE + 2 ];       // Leave room for a couple of LineFeeds.
    static uint8_t xdata * idata cp = cb;
	bool Ok;

    uint8_t idata c, i;

    if (!len)
    {
       if (!(len = Serial_CRx (port, cb, CMD_BUFF_SIZE)))
          return (Ok = FALSE);

       if (echo)
       {
          cp = cb;
          c = len;

          for (i = 0; i < c; i++)
          {
             if (CRET == *cp || LF == *cp)
             {                                   
                *cp++ = CRET;           // Insert <CR>.
                memcpy_xx (cp + 1, cp, len - i - 1);
                *cp = LF;            // Insert <LF>.
                len++;             
             }

             cp++;
          }      

          Serial_Tx (port, cb, len);       
       }
       cp = cb;
    }

    while (len)
    {                                   // Got some bytes.
       len--;
       c = *cp++;

       if (c >= ' ' )
       {
          if ((CLI_BASE == cli_index) && (',' == c))
          {
             while (cli_buff[ cli_index ] && cli_index < CLI_BUFF_SIZE)
                cli_index++;            // Find end of command.
          
             if (cli_index < CLI_BUFF_SIZE)
             {                          // Found old command.
                Serial_Tx (port, cli_buff, cli_index);       
                send_crlf ();
             }
             else
                *cli_buff = '\0';       // Null command, just echo prompt.

             cli_index   = CLI_BASE;    // Reset index to begining of command buffer.

             return (Ok = TRUE);
          }
          else
             put_char (&c);             // Just save it.
       }

       if ((CRET == c) || (LF == c))        
       {                                // Carriage Return or LineFeed.
          cli_buff[ cli_index ] = '\0'; // Stuff command terminator into buff.

          if (!echo)
          {
             Serial_Tx (port, cli_buff, cli_index);       
             send_crlf ();
          }
          else if (echo)
          {
             cp++;                      // Skip inserted CRET or LF.
             len--;
          }

          cli_index   = CLI_BASE;       // Reset index to begining of command buffer.
          return (Ok = TRUE);
       }
       else if (BS == c)
       {                                // Backspace.
          if (CLI_BASE != cli_index)
             cli_index--;
       }
       else if (CTRL_X == c)
          cli_index = CLI_BASE;         // Cancel, reset index CLI_BASE.
    }

    return (Ok = FALSE);
}

void put_char (uint8_t idata *c)
{
    if (cli_index < CLI_BUFF_SIZE - 1)
       cli_buff[ cli_index++ ] = *c;    // Just save it.
    else
       *c = CRET;                       // Force termination.
}

uint8_t htoc (uint8_t c)
{
    if (c > 9)
       c += 'A' - 10;
    else
       c += '0';
    
    return (c);
}

#pragma save
#pragma NOAREGS
static void io_timer(void) small reentrant
{
    io_timeout = 1;
}
#pragma restore

// character input
uint8_t getc (void)
{
    uint8_t xdata b;
    uint16_t len;
    uint16x_t *pstm;

    pstm = stm_start(milliseconds(30000),0,io_timer);

    do
    {
        len = Serial_CRx (port, &b, 1);
        if (!len)
           main_background ();
        if (io_timeout)
            return 0;
    }
    while (len == 0);

    stm_stop(pstm);
    io_timeout = 0;

    return b;
}

// Get next hexadecimal digit.
#undef CASE_
#define CASE_   0x20
static uint8_t rcv_digit (void)                     
{
    uint8_t c;

    do {
        c = getc ();
        if (io_timeout)
            return 0;
    } while (!isxdigit(c));

    c -= '0';              // '0' mapped to  0;

    if (c >= 10)
    {
        c &= ~CASE_;
        c -= 'A' - '0' - 10;            // 'A' mapped to 10.
    }

    return (c);
}

uint8_t rcv_hex (void)    // Convert ascii hexdecimal byte to binary 
{
    return ((rcv_digit () << 4) | rcv_digit ());
}

/***************************************************************************
 * History:
 * $Log: io.c,v $
 * Revision 1.29  2006/10/13 00:46:20  tvander
 * Removed compile options for 6530, 6515; renamed 6511 and 6513 to trace11 and trace13; Binary verified unchanged from previous version.
 *
 * Revision 1.28  2006/09/09 01:08:23  gmikef
 * *** empty log message ***
 *
 * Revision 1.27  2006/07/31 18:02:41  tvander
 * Fixed CLC timeout logic's integration with the CLI
 *
 * Revision 1.26  2006/07/25 17:21:11  tvander
 * Added io_timeout boolean.
 *
 * Revision 1.25  2006/07/25 00:26:34  tvander
 * *** empty log message ***
 *
 * Revision 1.24  2006/06/24 05:27:04  tvander
 * Clean build
 *
 * Revision 1.23  2006/06/23 20:46:04  tvander
 * Removed wait-for-io; it slowed response in brownout mode, and caused
 * hangs. The cure was definitely worse than the disease: a few clobbered characters after certain commands.
 *
 * Revision 1.22  2006/06/20 20:38:03  tvander
 * Fixed hang in wait for data to be sent.
 *
 * Revision 1.21  2006/06/15 19:56:04  tvander
 * Fixed misc. serial errors.
 *
 * Revision 1.20  2006/06/06 03:53:51  tvander
 * Added calibration count to access.c
 * Added to help files, at least, they compile for a 6513.
 * io.c support the calibration loader.
 * ser0cli.c and ser1cli.c were allocating too many timers.  Fixed.
 *
 * Revision 1.19  2006/05/30 17:16:19  tvander
 * Integrated new code to support the calibration loader
 *
 * Revision 1.18  2006/05/25 03:25:58  tvander
 * Some untested adjustments for calibration loader.
 * Added automatic enabling of UART2 and switching to pulse output on DIO2
 *
 * Revision 1.17  2006/04/06 20:57:10  tvander
 * I command is the same as I0 now.
 *
 * Revision 1.16  2006/03/07 23:57:08  tvander
 * Revised help system for accuracy.
 * Revised help system for compile flags.
 * Clean build
 *
 * Revision 1.15  2006/03/06 03:28:33  Michael T. Fischer
 * More 6530 prep.
 *
 * Revision 1.14  2006/03/03 11:24:47  Michael T. Fischer
 * Prep for 6530 LCD, etc.
 *
 * Revision 1.13  2006/01/16 20:11:20  tvander
 * Clean Keil build, all versions
 *
 * Revision 1.12  2006/01/10 03:54:33  gmikef
 * Added PDATA support for CE Outputs.
 *
 * Revision 1.10  2005/12/21 01:23:12  tvander
 * 13 and 11 are different. apparently
 *
 * Revision 1.9  2005/11/10 22:51:31  tvander
 * 6520 has battery mode commands.
 * Brownout always has decimal point 7.
 * LCD Mode always has decimal points 7 and 6.
 * Sag detection is disabled.
 *
 * Revision 1.8  2005/11/05 02:23:26  gmikef
 * Fixed bug in XON/XOFF protocol.
 * Detect and notify of out of range download data.
 *
 * Revision 1.7  2005/11/02 03:06:46  gmikef
 * Xon/Xoff flow control working.
 *
 * Revision 1.6  2005/10/18 02:17:08  tvander
 * Access CLI in brownout by pressing reset.
 * Debugged serial 1 usage from CLI.
 * Implemented scrolling display as M17
 *
 * Revision 1.5  2005/10/08 04:41:17  tvander
 * Fixed priority inversion.
 * Rewrote watchdog to work in brownout, but of course it doesn't work.
 * Watchdog can now be defeated by clearing watchdog option to 0.
 * Reorganized watt hour modules (at last!).
 * Disabled reading of STATUS in 6521_cli because the CE's status is always SAG.
 * Tested with 6521_CLI; measurements seem to work.
 * Fixed other builds.
 *
 * Revision 1.4  2005/09/22 23:44:54  tvander
 * Clean build all models and unit tests, updated copyright to be fore Teridian
 *
 * Revision 1.3  2005/09/12 07:47:28  tvander
 * Power measurement is stable, with no creep.
 * VARh measurement is stable, with no creep.
 * Pulse sources work.
 * Full access to MPU variables.
 * Rolled date.
 * Clock software works.
 *
 * Revision 1.2  2005/08/30 01:56:50  gmikef
 * *** empty log message ***
 *
 * Revision 1.1  2005/08/28 02:23:57  gmikef
 * *** empty log message ***
 *
 * Revision 1.3  2005/08/20 01:32:44  gmikef
 * *** empty log message ***
 *
 * Revision 1.2  2005/08/19 01:04:37  gmikef
 * *** empty log message ***
 *
 * Revision 1.1  2005/08/18 02:56:07  gmikef
 * *** empty log message ***
 *
 *

 * 2005 AUGUST 17; First Version. 
 * Copyright (C) 2005 Teridian Semiconductor Corp. All Rights Reserved.	   *
 * this program is fully protected by the United States copyright          *
 * laws and is the property of Teridian Semiconductor Corporation.         *
 ***************************************************************************/
#endif