/*
 * Tclwinserial.c --
 *
 *  This file implements the Windows-specific serial port functions,
 *  and the "serial" channel driver.
 *
 * Copyright (c) 1999 by Scriptics Corp.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 * Changes by Rolf.Schroedter@dlr.de June 25-27, 1999
 *
 * RCS: @(#) $Id: tclWinSerial.c,v 1.9 1999/11/24 20:55:17 hobbs Exp $
 */

#include "tclWinInt.h"

#include <dos.h>
#include <fcntl.h>
#include <io.h>

                 * one time after write operation */

/*
 * Default time to block between checking status on the serial port.
 */
#define SERIAL_DEFAULT_BLOCKTIME    10  /* 10 msec */

/*
 * Define Win32 read/write error masks returned by ClearCommError()
 */
#define SERIAL_READ_ERRORS	( CE_RXOVER | CE_OVERRUN | CE_RXPARITY \
				| CE_FRAME  | CE_BREAK )
#define SERIAL_WRITE_ERRORS	( CE_TXFULL )

/*
 * This structure describes per-instance data for a serial based channel.
 */

typedef struct SerialInfo {
    HANDLE handle;
    struct SerialInfo *nextPtr; /* Pointer to next registered serial. */
    Tcl_Channel channel;        /* Pointer to channel structure. */
    int validMask;              /* OR'ed combination of TCL_READABLE,
                                 * TCL_WRITABLE, or TCL_EXCEPTION: indicates
                                 * which operations are valid on the file. */
    int watchMask;              /* OR'ed combination of TCL_READABLE,
                                 * TCL_WRITABLE, or TCL_EXCEPTION: indicates
                                 * which events should be reported. */
    int flags;                  /* State flags, see above for a list. */
    int writable;               /* flag that the channel is readable */
    int readable;               /* flag that the channel is readable */
    int blockTime;              /* max. blocktime in msec */
    DWORD error;		/* pending error code returned by 
				 * ClearCommError() */
    DWORD lastError;		/* last error code, can be fetched with 
				 * fconfigure chan -lasterror */
} SerialInfo;

typedef struct ThreadSpecificData {
    /*
     * The following pointer refers to the head of the list of serials
     * that are being watched for file events.
     */

    ClientData data,    /* Not used. */
    int flags)          /* Event flags as passed to Tcl_DoOneEvent. */
{
    SerialInfo *infoPtr;
    SerialEvent *evPtr;
    int needEvent;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    COMSTAT cStat;

    if (!(flags & TCL_FILE_EVENTS)) {
        return;
    }

    /*

        /*
         * If any READABLE or WRITABLE watch mask is set
         * call ClearCommError to poll cbInQue,cbOutQue
         * Window errors are ignored here
         */

        if( infoPtr->watchMask & (TCL_WRITABLE | TCL_READABLE) ) {
            if( ClearCommError( infoPtr->handle, &infoPtr->error, &cStat ) ) {
		/*
		 * Look for empty output buffer.  If empty, poll.
		 */

                if( infoPtr->watchMask & TCL_WRITABLE ) {
		    /*
		     * force fileevent after serial write error
		     */
		    if (((infoPtr->flags & SERIAL_WRITE) != 0) &&
			    ((cStat.cbOutQue == 0) ||
				    (infoPtr->error & SERIAL_WRITE_ERRORS))) {
                        /*
			 * allow only one fileevent after each callback
			 */

                        infoPtr->flags &= ~SERIAL_WRITE;
                        infoPtr->writable = 1;
                        needEvent = 1;
                    }
                }
		
                /*
                 * Look for characters already pending in windows queue.
		 * If they are, poll.
                 */

                if( infoPtr->watchMask & TCL_READABLE ) {
		    /*
		     * force fileevent after serial read error
		     */
                    if( (cStat.cbInQue > 0) || 
			    (infoPtr->error & SERIAL_READ_ERRORS) ) {
                        infoPtr->readable = 1;
                        needEvent = 1;
                    }
                }
            }
        }

    int bufSize,                /* How much space is available
                                 * in the buffer? */
    int *errorCode)             /* Where to store error code. */
{
    SerialInfo *infoPtr = (SerialInfo *) instanceData;
    DWORD bytesRead = 0;
    DWORD err;

    COMSTAT cStat;

    *errorCode = 0;

    /* 
     * Check if there is a CommError pending from SerialCheckProc
     */
    if( infoPtr->error & SERIAL_READ_ERRORS ){
	goto commError;
    }

    /*
     * Look for characters already pending in windows queue.
     * This is the mainly restored good old code from Tcl8.0
     */

    if( ClearCommError( infoPtr->handle, &infoPtr->error, &cStat ) ) {
        /*
	 * Check for errors here, but not in the evSetup/Check procedures
	 */

        if( infoPtr->error & SERIAL_READ_ERRORS ) {
	    goto commError;

        }
        if( infoPtr->flags & SERIAL_ASYNC ) {
	    /*
	     * NON_BLOCKING mode:
	     * Avoid blocking by reading more bytes than available
	     * in input buffer
	     */

        err = GetLastError();
        if (err != ERROR_IO_PENDING) {
            goto error;
        }
    }
    return bytesRead;

    error:
    TclWinConvertError(GetLastError());
    *errorCode = errno;
    return -1;

    commError:
    infoPtr->lastError = infoPtr->error;  /* save last error code */
    infoPtr->error = 0;			  /* reset error code */
    *errorCode = EIO;			  /* to return read-error only once */
    return -1;
}

/*
 *----------------------------------------------------------------------
 *
 * SerialOutputProc --
 *

    int toWrite,                /* How many bytes to write? */
    int *errorCode)             /* Where to store error code. */
{
    SerialInfo *infoPtr = (SerialInfo *) instanceData;
    DWORD bytesWritten, err;

    *errorCode = 0;

    /*
     * Check if there is a CommError pending from SerialCheckProc
     */
    if( infoPtr->error & SERIAL_WRITE_ERRORS ){
	infoPtr->lastError = infoPtr->error;  /* save last error code */
	infoPtr->error = 0;		      /* reset error code */
	*errorCode = EIO;		/* to return read-error only once */
	return -1;
    }

    /*
     * Check for a background error on the last write.
     * Allow one write-fileevent after each callback
     */

    if( toWrite ) {

    infoPtr->channel = Tcl_CreateChannel(&serialChannelType, channelName,
            (ClientData) infoPtr, permissions);


    infoPtr->readable = infoPtr->writable = 0;
    infoPtr->blockTime = SERIAL_DEFAULT_BLOCKTIME;
    infoPtr->lastError = infoPtr->error = 0;

    /*
     * Files have default translation of AUTO and ^Z eof char, which
     * means that a ^Z will be accepted as EOF when reading.
     */

    Tcl_SetChannelOption(NULL, infoPtr->channel, "-translation", "auto");
    Tcl_SetChannelOption(NULL, infoPtr->channel, "-eofchar", "\032 {}");

    return infoPtr->channel;
}

/*
 *----------------------------------------------------------------------
 *
 * SerialErrorStr --
 *
 *  Converts a Win32 serial error code to a list of readable errors
 *
 *----------------------------------------------------------------------
 */
static void
SerialErrorStr(error, dsPtr)
    DWORD error;           /* Win32 serial error code */
    Tcl_DString *dsPtr;    /* Where to store string */
{
    if( (error & CE_RXOVER) != 0) {
	Tcl_DStringAppendElement(dsPtr, "RXOVER");
    }
    if( (error & CE_OVERRUN) != 0) {
	Tcl_DStringAppendElement(dsPtr, "OVERRUN");
    }
    if( (error & CE_RXPARITY) != 0) {
	Tcl_DStringAppendElement(dsPtr, "RXPARITY");
    }
    if( (error & CE_FRAME) != 0) {
	Tcl_DStringAppendElement(dsPtr, "FRAME");
    }
    if( (error & CE_BREAK) != 0) {
	Tcl_DStringAppendElement(dsPtr, "BREAK");
    }
    if( (error & CE_TXFULL) != 0) {
	Tcl_DStringAppendElement(dsPtr, "TXFULL");
    }
    if( (error & ~(SERIAL_READ_ERRORS | SERIAL_WRITE_ERRORS)) != 0) {
	char buf[TCL_INTEGER_SPACE + 1];
	wsprintfA(buf, "%d", error);
	Tcl_DStringAppendElement(dsPtr, buf);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * SerialSetOptionProc --
 *
 *  Sets an option on a channel.

        ((len > 1) && (strncmp(optionName, "-pollinterval", len) == 0))) {
        char buf[TCL_INTEGER_SPACE + 1];

        valid = 1;
        wsprintfA(buf, "%d", infoPtr->blockTime);
        Tcl_DStringAppendElement(dsPtr, buf);
    }

    /*
     * get option -lasterror
     * option is readonly and returned by [fconfigure chan -lasterror]
     * but not returned by unnamed [fconfigure chan]
     */

    if ( (len > 1) && (strncmp(optionName, "-lasterror", len) == 0) ) {
	valid = 1;
	SerialErrorStr(infoPtr->lastError, dsPtr);
    }

    if (valid) {
        return TCL_OK;
    } else {
        return Tcl_BadChannelOption(interp, optionName,
		"mode pollinterval lasterror");
    }
}