serdpcpl.c

一个C语言写的读入位置跟踪器数据的源程序

                if ((outputmode != STREAM) || (rxchar == RXTIMEOUT))
                {
                    clear_rx();
                    return(RXERRORS);
                }

                /*
                   If an Error occured and we are in STREAM mode, resynch
                */
                if (outputmode == STREAM)
                {
                    /*
                       Resynch
                       ...and keep track of the phase error
                    */
                    phaseerror_count++;
                    resynch = TRUE;
                    continue;
                }
            }

            /*
                Check to make sure the the phase bit is a '1'
                If not, then if STREAM mode, resynch
                else, return with error
            */
            if (!(rxchar & 0x80))
            {
                if (outputmode == STREAM)
                {
                    /*
                       Resynch
                       ...and keep track of the phase error
                    */
                    phaseerror_count++;
                    resynch = TRUE;
                    continue;
                }
                else
                {
                     clear_rx();
                     return(RXPHASEERROR);
                }
            }
        }
        else    /* rxcount > 0 */
        {
            /*
                Get remainder of Block of data from the serial port, recsize characters
                and store them in rxbuf
            */
            if ((rxchar = waitforchar()) >= 0)  /* no errors */
            {
                /*
                   Check Phase bit
                */
                if (rxchar & 0x80)              /* check to see that phase bit = '0' */
                {
                    if (outputmode == STREAM)
                    {
                        phaseerror_count++;     /* keep track of phase errors */
                        resynch = TRUE;         /* loop again flag */
                        continue;
                    }
                    else
                    {
                        clear_rx();
                        return(RXPHASEERROR);       /* return phase error */
                    }
                }
            }
            else
            {
                if (outputmode == STREAM)
                {
                    phaseerror_count++;     /* keep track of phase errors */
                    resynch = TRUE;         /* loop again flag */
                    continue;
                }
                else
                {              
                    clear_rx();
                    return(RXERRORS);
                }
            }
        }
        /*
           Store the received character
        */
        *rxbufptr++ = rxchar;   /* store and adjust pointer */
        rxcount++;              /* increment */
    }
    while ((resynch) || (rxcount < recsize));

    /*
        Return the number of characters received
    */
    return(rxcount);
}

/*
    send_serial_cmd     -    Send Serial Command to the Bird port

    Prototype in:       serial.h

    Parameters Passed:  cmd         -   string to send to the serial point
                        cmdsize     -   size of the cmd string (cmd is NOT
                                        NULL terminated, since the data can
                                        be NULL)
    Return Value:       number of characters transmitted

    Remarks:            Routine will send a string of characters to the serial
                        port.  The string is pointed to by cmd and all
                        characters will be sent upto but NOT including
                        the NULL
*/
int send_serial_cmd(cmd,cmdsize)
unsigned char * cmd;
short cmdsize;
{
	short txcount = 0;
    unsigned char rs232tofbbcmd;

    /*
        Send the RS232 to FBB Prefice Character if non-zero
    */
    if (rs232tofbbaddr > 0)
    {
        if (rs232tofbbaddr <= 15)
            /* pass through command 0-15 */
            rs232tofbbcmd = (unsigned char)(0xF0 | rs232tofbbaddr);
        else
            /* pass through command 16-31 */
            rs232tofbbcmd = (unsigned char)(0xE0 | rs232tofbbaddr-16);

        while (send_serial_char(rs232tofbbcmd) == TXNOTEMPTY);
    }

    while (txcount < cmdsize)
    {
        /*
            Wait until the character goes out OK
        */
        while ((send_serial_char(*cmd)) == TXNOTEMPTY);

        /*
            point to the next character
        */
        cmd++;
        txcount++;
    }
    return(txcount++);
}

/*
    get_serial_char -   Get 1 Character from the serial port if one is available

    Prototype in:       serial.h

    Parameters Passed:  void

    Return Value:       returns the

    Remarks:            returns the receive character if successful,
                        RXERRORS if recieve errors
                        NODATAAVAIL if no characer available
*/
int get_serial_char()
{
	short linestatus;

    /*
        Get line status and check if character is available
            else return
    */
    if ((linestatus = INPORTB(com_base + LINESTATUS)) & DATARDY)
    {
        /*
            check for errors and return
        */
        if ((rxerrors = (linestatus & RXERRORMSK)) != 0)
            return(RXERRORS);

        /*
            Send back the RX data
        */
        return(INPORTB(com_base + RXBUF));
    }
    else
    {
        /*
            check for errors and return
        */
        if ((rxerrors = (linestatus & RXERRORMSK)) != 0)
            return(RXERRORS);

        return(NODATAAVAIL);
    }
}
/*
    send_serial_char    -   Send one serial char to the serial port

    Prototype in:       serial.h

    Parameters Passed:  chr     -   character to send to the serial port

    Return Value:       returns TRUE if successful, or TXNOTEMPTY if
                        cannot send because the holding register is not
                        empty

    Remarks:
*/
int send_serial_char(chr)
unsigned char chr;
{

    /*
        Get line status and check if transmit holding register is empty
            else return TXNOTEMPTY
    */
    if (!(INPORTB(com_base + LINESTATUS) & TXHOLDEMPTY))
            return(TXNOTEMPTY);

    /*
        Else, Transmit the Character
    */
    OUTPORTB(com_base + TXBUF, (char) chr);
    return(TRUE);
}

/*
    waitforchar         -   Wait for a Character from the Serial Port

    Prototype in:       serial.h

    Parameters Passed:  void

    Return Value:       returns the receive character if successful,
                        RXERRORS if recieve errors,
                        RXTIMEOUT if a time out occurs before a
                        character is ready

    Remarks:            Routine waits for the TIMEOUTINTICKS period
                        for a character

*/
int waitforchar()
{
	short rxchar;
    long starttime;

    /*
        Get the time now in ticks
    */
    starttime = GETTICKS;

    /*          
        Wait until a character is available
        ....leave loop if errors or character available
    */
    while ((rxchar = get_serial_char()) == NODATAAVAIL)
    {
        /*
            Check to see if a timeout occured
        */
        if ((GETTICKS - starttime) > (long)((RXTIMEOUTINSECS * 1000) / TICK_MSECS))
        {
            printf("\n** ERROR ** receiver timed out\n");
            return(RXTIMEOUT);
        }
    }


    /*
        return if RX errors
    */
    if (rxchar < 0)
        return(RXERRORS);

    /*
        Everything is OK...return the character
    */
    return(rxchar);
}

/*
    waitforphase        -   Wait for a Character with phase bit set

    Prototype in:       serial.h

    Parameters Passed:  void

    Return Value:       returns the received character if successful,
                        or RXERRORS if an error occurs

    Remarks:            waits for a character to be received with the
                        most significant bit (bit 7) set to a '1'.  Characters
                        received with bit 7 = '0' are thrown away.
                        Routine waits for the TIMEOUTINTICKS period.
*/
int waitforphase()
{
	short rxchar;

    /*
        Wait until waitforchar returns a character or error
    */
    while (((rxchar = waitforchar()) & 0x80) == 0)
    {
        /*
            return if errors
        */
        if (rxchar < 0)
            return(RXERRORS);
    }

    /*
        Everything is OK...return the character
    */
    return(rxchar);
}