back using intbv
back use intbv instead of fixbv
using vvp and iverilog with GTKWave
vvp test_counter
VCD info: dumpfile tb_counter.vcd opened for output.
At time                    0, count_out  = xxxxx (x)
At time                 3500, count_out  = 00000 (0)
At time                 4500, count_out  = 00001 (1)
At time                 5500, count_out  = 00000 (0)
At time                 6500, count_out  = 1ffff (131071)
At time                 7500, count_out  = 00000 (0)
At time                 8500, count_out  = 00001 (1)
At time                 9500, count_out  = 00002 (2)
At time                10500, count_out  = 00003 (3)
At time                11500, count_out  = 00004 (4)
At time                12500, count_out  = 00005 (5)
At time                13500, count_out  = 00006 (6)
At time                14500, count_out  = 00007 (7)
At time                15500, count_out  = 00008 (8)
At time                16500, count_out  = 00009 (9)
** VVP Stop(0) **
** Flushing output streams.
** Current simulation time is 16700 ticks.
simulation is working