SONLastTime

  SONLASTTIME returns information about the last entry on a channel
  before a specified time

  Implemented through SONLastTime.dll

 [time, data, markers, markerflag]=...
                        SONGETADCDATA(fh, chan, eTime, sTime{, FilterMask})

    INPUTS: FH SON File Handle
            CHAN Channel number (1 to SONMaxChannels)
            STIME Searches back from this time
            ETIME stops search at this time (eTime must be less than sTime)
            FILTERMASK, if present, a filter mask

    OUTPUTS: TIME The time of the last data point between ETIME and STIME
                    or a negative error code
             DATA Value at TIME for an ADC or Real channel.
                    For an EventBoth channel the InitLow value
             MARKERS the marker codes for the event at TIME for
                    a marker channel
             MARKERFLAG Set to 1 if CHAN is a marker channel, 0 otherwise

  Author:Malcolm Lidierth
  Matlab SON library:
  Copyright © The Author & King's College London 2005-2006