ns_GetEventData

 ns_GetEventData   Retrieves event data by index

    Usage:
       [ns_RESULT, TimeStamp, Data, DataSize] = 
                                    ns_GetEventData(hFile, EntityID, Index)

    Description:
        Returns the data values from the file referenced by hFile and the
        Event Entity EntityID.  The Event data entry specified by Index
        is written to Data and the timestamp of the entry is returned to
        TimeStamp.  Upon return of the function, the value at DataSize
        contains the number of bytes actually written to Data.

    Parameters:
        hFile           Handle/Indentification number to an open file.
        EntityID        Identification number of the entity in the data
                        file.
        Index           The index number of the requested Event data item.

    Return Values:
        TimeStamp       Variable that receives the timestamp of the Event
                        data item.
        Data            Variable that receives the data for the Event entry.
                        The format of Event data is specified by the member
                        EventType in ns_EVENTINFO.
        DataSize        Variable that receives the actual number of bytes
                        of data retrieved in the data buffer.
        ns_RESULT   This function returns ns_OK if the file is successfully
                    opened. Otherwise one of the following error codes is 
                    generated:

                        ns_BADFILE      Invalid file handle passed to 
                                        function
                        ns_BADENTITY    Invalid or inappropriate entity 
                                        identifier specified
                        ns_BADINDEX     Invalid entity index specified
                        ns_FILEERROR    File access or read error

    Copyright (C) 2003 Neuroshare Project
    Author: Almut Branner
    Last modification: 8/11/2003