class BBDecData: public THaApparatus

 BBDecData
  Originally THaDecData... adapted for use with BigBiteLib
  by Bryan Moffit, March 2008.

 Hall A miscellaneous decoder data, which typically does not
 belong to a detector class.
 Provides global data to analyzer, and
 a place to rapidly add new channels.

 Normally the user should have a file "decdata.map" in their pwd
 to define the locations of raw data for this class (only).
 But if this file is not found, we define a default mapping, which
 was valid at least at one point in history.

 The scheme is as follows:

    1. In Init() we define a list of global variables which are tied
       to the variables of this class.  E.g. "timeroc2".

    2. Next we build a list of "BBdataLoc" objects which store information
       about where the data are located.  These data are either directly
       related to the variables of this class (e.g. timeroc2 is a raw
       data word) or one must analyze them to obtain a variable.

    3. The BBdataLoc objects may be defined by decdata.map which has an
       obvious notation (see ~/examples/decdata.map).  The entries are either
       locations in crates or locations relative to a unique header.
       If decdata.map is not in the pwd where you run analyzer, then this
       class uses its own internal DefaultMap().

    4. The BBdataLoc objects pertain to one data channel (e.g. a fastbus
       channel) and and may be multihit.

    5. To add a new variable, if it is on a single-hit channel, you may
       imitate 'synchadc1' if you know the (crate,slot,chan), and
       imitate 'timeroc2' if you know the (crate,header,no-to-skip).
       If your variable is more complicated and relies on several
       channels, imitate the way 'bits' leads to 'evtypebits'.

 R. Michaels, March 2002

 OR  (NEW as of April 2004:  R.J. Feuerbach)
       If you are simply interested in the readout of a channel, create
       a name for it and give the location in the map file and a
       global variable will be automatically created to monitor that channel.
     Unfortunately, this leads to a limitation of using arrays as opposed
     to variable-sized vector for the readout. Currently limited to 16 hits
     per channel per event.