Creating Streams Based on Bitmasks

It can be useful to produce a set of streams based on different criteria. Although this can be done by creating a set of run/event text files as described in the preceeding section, that method is rather inefficient. There is a new command invoked via:

which produces a set of output d0dad files based on a text file defining the correspondance between streams and events. Three files are needed:

1. bitmask_file - This file contains a list of run/event pairs and the bitmasks defining the streams to which the event belongs. The format of each line in the list is: \

   in which bbbb is a hex bitmask. A set bit implies that the event is written to the corresponding stream. Up to 160 streams may be defined and the entries must be sorted by run/event.

2. bitmask_defn - This is a file which contains one line for each bit used. The line contains the d0dad file name. If no output file is desired for a given bit, the corresponding line must be blank. For example if bit #1 is used to create a file called BIT1.D0DADF, bit 2 is unused, bit #3 is used to create/update a file called BIT3.D0DADF and bit #4 is used to create/update file called BIT4.D0DAD, the bitmask definition text file would be:

            BIT1.D0DADF
                                             <-- Blank line in file
            BIT3.D0DADF
            BIT4.D0DADF

3. event_catalog - The event catalog defined as for the preceeding section