[CU]时钟1-可变时钟

资料来源:

(1) 《UVM实战》

1.不同测试用例时钟频率不同,同一测试用例时钟频率保持不变;

//my_case0.sv
function void my_case0::build_phase(uvm_phase phase);
    ...
    uvm_config_db#(real)::set(this,"","clk_half_period",200.0);
    ...
endfunction

//top_tb.sv
initial begin 
    static real clk_half_period=100.0;
    clk=0;
    #1;
    if(uvm_config_db#(real)::get(uvm_root::get(),"uvm_test_top","clk_half_period",clk_half_period))
        `uvm_info("top_tb",$sformatf("clk_half_period is %0f",clk_half_period),UVM_MEDIUM)

    forever begin
        #(clk_half_period*1.0ns) clk=~clk;
  end
end

2.同一测试用例中存在时钟频率变换的情况,但是不关心过渡期时间段的时钟频率,而只关心过渡期前和过渡期后的时钟频率;

//my_case0.sv
task my_case0::main_phase(uvm_phase phase);
    #100000;
    uvm_config_db#(real)::set(this,"","clk_half_period",200.0);
    #100000;
    uvm_config_db#(real)::set(this,"","clk_half_period",150.0);
endtask

//top_tb.sv
initial begin 
    static real clk_half_period=100.0;
    clk=0;
  fork
        //thread1
        forever begin
            uvm_config_db#(real)::wait_modified(uvm_root::get(),"uvm_test_top","clk_half_period");
            void'(uvm_config_db#(real)::get(uvm_root::get(),"uvm_test_top","clk_half_period",clk_half_period));
            `uvm_info("top_tb",$sformatf("clk_half_period is %0f",clk_half_period),UVM_MEDIUM)
        end
        //thread2
        forever begin
          #(clk_half_period*1.0ns) clk=~clk;
        end
end

3.同一测试用例中存在时钟频率变换的情况,但是既关心过渡期前和过渡期后的时钟频率,也关心过渡期时间段的时钟频率;