GLOBAL_SIM_BASE_CLK clk reset a
0 0 1 0X0 
0 1 1 0X0 
0 0 0 0X0 
0 1 0 0X0 
0 0 0 0X1 
0 1 0 0X1 
0 0 0 0X2 
0 1 0 0X2 
0 0 0 0X3 
0 1 0 0X3  