ns_GetSegmentData

 ns_GetSegmentData   Retrieves segment data by index

    Usage:
       [ns_RESULT, TimeStamp, Data, SampleCount, UnitID] = 
                                ns_GetSegmentData(hFile, EntityID, Index)

    Description:
        Returns the Segment data values in entry Index of the entity
        EntityID from the file referenced by hFile. The data values are
        returned in Data. The timestamp of the entry id returned in
        TimeStamp. The number of samples written to Data is returned in
        SampleCount. 
        The data variable should be accessed as a 2-dimensional array for
        samples and sources.  

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

    Remarks:
        A zero unit ID is unclassified, then follow unit 1, 2, 3, etc. Unit
        255 is noise.

    Return Values:
        TimeStamp   Time stamp of the requested Segment data item.
        Data        Variable to receive the requested data.
        SampleCount Number of samples returned in the data variable.
        UnitID      Unit classification code for the Segment Entity.
        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: 10/24/2003