Descriptions:
   The LIRS algorithm is described in the wiki page:
   http://en.wikipedia.org/wiki/LIRS_caching_algorithm.
   In the wiki page, there is a graph illustrating the operations
   of LIRS on two stacks (Stack S and Stack Q)

   ./trace/{2_pools, cs, cpp, gli, ps, sprite, multi1,
   multi2, multi3}.trc are the trace files. As these traces have long
   reference sequences, if you just want to run partial of them(from the
   very beginning to a certain point rather than the very end), you can
   simply insert a breakpoint "*" after a certain line, indicating that the stack
   information needs to be printed into files right after the
   reference before the "*" is processed. By default, there is a
   breakpoint at the end of trace file.

   For example, there are two "*" in ./traces/cs.trc, indicating that
   the HIR/LIR stack information as well as eviction sequence should be
   printed for the following three access sequences:
   {0..14}, {0..22} and {0..file-end}. The output file name format is:
   TRACENAME-output-{LIR, HIR, EVICTED}-CHECKPOINTNUM.log. In the names,
   "LIR" means the contents of the LIRS stack (Stack S in the wiki
   page), "HIR" means the contents of the LIRS queue (Stack Q in the
   wiki page), and "EVICTED" means the sequence of pages that are
   evicted. Please see the sample files under ./traces for details.

   In the output file of LIR stack,
   "R" refers as "resident"; "NR" refers as "non-resident";
   "H" refers as "HIR block"; "L" refers as "LIR block";

   For other details, please read the source codes.

How to run the program:
  ./lirs ./traces/TRACE_NAME
  For example, "./lirs ./traces/cs" will run the LIRS simulation
  on the trace "cs.trc" and the information of HIR/LIR, as well as
  the eviction sequence will be printed out into the files respectively.