30 UVM Adder Testbench Example-编程知识

1 Adder Design

加法器设计在时钟的上升沿产生两个变量的加法。复位信号用于clear out信号。
注：加法器可以很容易地用组合逻辑开发。引入时钟和重置，使其具有测试台代码中时钟和重置的样子/风格。

module adder(input clk, reset, input [7:0] in1, in2, output reg [8:0] out);always@(posedge clk or posedge reset) begin if(reset) out <= 0;else out <= in1 + in2;end
endmodule

2 Testbench Code

2.1 Sequence Item

sequence item类包含必要的激励产生数据成员。

class seq_item extends uvm_sequence_item;rand bit [7:0] ip1, ip2;bit [8:0] out;function new(string name = "seq_item");super.new(name);endfunction`uvm_object_utils_begin(seq_item)`uvm_field_int(ip1,UVM_ALL_ON)`uvm_field_int(ip2,UVM_ALL_ON)`uvm_object_utils_endconstraint ip_c {ip1 < 100; ip2 < 100;}
endclass

2.2 Sequence

sequence创建激励并通过sequencer驱动到driver。

class base_seq extends uvm_sequence#(seq_item);seq_item req;`uvm_object_utils(base_seq)function new (string name = "base_seq");super.new(name);endfunctiontask body();`uvm_info(get_type_name(), "Base seq: Inside Body", UVM_LOW);`uvm_do(req);endtask
endclass

2.3 Sequencer

sequencer是在sequence和driver之间建立连接的中介。

class seqcr extends uvm_sequencer#(seq_item);`uvm_component_utils(seqcr)function new(string name = "seqcr", uvm_component parent = null);super.new(name, parent);endfunctionfunction void build_phase(uvm_phase phase);super.build_phase(phase);endfunction
endclass

2.4 Driver

driver驱动随机后的事务transactions或者sequence item给pin-level接口的DUT。

class driver extends uvm_driver#(seq_item);virtual add_if vif;`uvm_component_utils(driver)function new(string name = "driver", uvm_component parent = null);super.new(name, parent);endfunctionfunction void build_phase(uvm_phase phase);super.build_phase(phase);if(!uvm_config_db#(virtual add_if) :: get(this, "", "vif", vif))`uvm_fatal(get_type_name(), "Not set at top level");endfunctiontask run_phase (uvm_phase phase);forever begin// Driver to the DUTseq_item_port.get_next_item(req);`uvm_info(get_type_name, $sformatf("ip1 = %0d, ip2 = %0d", req.ip1, req.ip2), UVM_LOW);vif.ip1 <= req.ip1;vif.ip2 <= req.ip2;seq_item_port.item_done();endendtask

2.5 Monitor

UVM monitor是一个passive component，用于使用虚拟接口捕获DUT信号并将其转换为序列项sequence item格式。

class monitor extends uvm_monitor;virtual add_if vif;uvm_analysis_port #(seq_item) item_collect_port;seq_item mon_item;`uvm_component_utils(monitor)function new(string name = "monitor", uvm_component parent = null);super.new(name, parent);item_collect_port = new("item_collect_port", this);mon_item = new();endfunctionfunction void build_phase(uvm_phase phase);super.build_phase(phase);if(!uvm_config_db#(virtual add_if) :: get(this, "", "vif", vif))`uvm_fatal(get_type_name(), "Not set at top level");endfunctiontask run_phase (uvm_phase phase);forever beginwait(!vif.reset);@(posedge vif.clk);mon_item.ip1 = vif.ip1;mon_item.ip2 = vif.ip2;`uvm_info(get_type_name, $sformatf("ip1 = %0d, ip2 = %0d", mon_item.ip1, mon_item.ip2), UVM_HIGH);@(posedge vif.clk);mon_item.out = vif.out;item_collect_port.write(mon_item);endendtask
endclass

2.6 Agent

agent是包含并连接driver，monitor和sequencer实例的容器。

class agent extends uvm_agent;`uvm_component_utils(agent)driver drv;seqcr seqr;monitor mon;function new(string name = "agent", uvm_component parent = null);super.new(name, parent);endfunctionfunction void build_phase(uvm_phase phase);super.build_phase(phase);if(get_is_active == UVM_ACTIVE) begin drv = driver::type_id::create("drv", this);seqr = seqcr::type_id::create("seqr", this);endmon = monitor::type_id::create("mon", this);endfunctionfunction void connect_phase(uvm_phase phase);if(get_is_active == UVM_ACTIVE) begin drv.seq_item_port.connect(seqr.seq_item_export);endendfunction
endclass

2.7 Scoreboard

UVM scoreboard是检查DUT功能的组件。它使用analysis port从monitor接收事务以进行检查。

class scoreboard extends uvm_scoreboard;uvm_analysis_imp #(seq_item, scoreboard) item_collect_export;seq_item item_q[$];`uvm_component_utils(scoreboard)function new(string name = "scoreboard", uvm_component parent = null);super.new(name, parent);item_collect_export = new("item_collect_export", this);endfunctionfunction void build_phase(uvm_phase phase);super.build_phase(phase);endfunctionfunction void write(seq_item req);item_q.push_back(req);endfunctiontask run_phase (uvm_phase phase);seq_item sb_item;forever beginwait(item_q.size > 0);if(item_q.size > 0) beginsb_item = item_q.pop_front();$display("----------------------------------------------------------------------------------------------------------");if(sb_item.ip1 + sb_item.ip2 == sb_item.out) begin`uvm_info(get_type_name, $sformatf("Matched: ip1 = %0d, ip2 = %0d, out = %0d", sb_item.ip1, sb_item.ip2, sb_item.out),UVM_LOW);endelse begin`uvm_error(get_name, $sformatf("NOT matched: ip1 = %0d, ip2 = %0d, out = %0d", sb_item.ip1, sb_item.ip2, sb_item.out));end$display("----------------------------------------------------------------------------------------------------------");endendendtaskendclass

2.8 Environment

env提供了包含agent，scoreboard，和其他验证组件的容器。

class env extends uvm_env;`uvm_component_utils(env)agent agt;scoreboard sb;function new(string name = "env", uvm_component parent = null);super.new(name, parent);endfunctionfunction void build_phase(uvm_phase phase);super.build_phase(phase);agt = agent::type_id::create("agt", this);sb = scoreboard::type_id::create("sb", this);endfunctionfunction void connect_phase(uvm_phase phase);agt.mon.item_collect_port.connect(sb.item_collect_export);endfunction
endclass

2.9 Test

test位于组件层次顶部。

class base_test extends uvm_test;env env_o;base_seq bseq;`uvm_component_utils(base_test)function new(string name = "base_test", uvm_component parent = null);super.new(name, parent);endfunctionfunction void build_phase(uvm_phase phase);super.build_phase(phase);env_o = env::type_id::create("env_o", this);endfunctiontask run_phase(uvm_phase phase);phase.raise_objection(this);bseq = base_seq::type_id::create("bseq");repeat(10) begin #5; bseq.start(env_o.agt.seqr);endphase.drop_objection(this);`uvm_info(get_type_name, "End of testcase", UVM_LOW);endtask
endclass

2.10 Testbench Top

testbench是一个静态容器，实例化DUT和接口。

module tb_top;bit clk;bit reset;always #2 clk = ~clk;initial begin//clk = 0;reset = 1;#5; reset = 0;endadd_if vif(clk, reset);adder DUT(.clk(vif.clk),.reset(vif.reset),.in1(vif.ip1),.in2(vif.ip2),.out(vif.out));initial begin// set interface in config_dbuvm_config_db#(virtual add_if)::set(uvm_root::get(), "*", "vif", vif);endinitial beginrun_test("base_test");end
endmodule

2.11 Execute Complete Code

Output：

UVM_INFO base_seq.sv(10) @ 5: uvm_test_top.env_o.agt.seqr@@bseq [base_seq] Base seq: Inside Body
UVM_INFO driver.sv(20) @ 5: uvm_test_top.env_o.agt.drv [driver] ip1 = 22, ip2 = 14
----------------------------------------------------------------------------------------------------------
UVM_INFO scoreboard.sv(28) @ 10: uvm_test_top.env_o.sb [scoreboard] Matched: ip1 = 22, ip2 = 14, out = 36
----------------------------------------------------------------------------------------------------------
UVM_INFO base_seq.sv(10) @ 10: uvm_test_top.env_o.agt.seqr@@bseq [base_seq] Base seq: Inside Body
UVM_INFO driver.sv(20) @ 10: uvm_test_top.env_o.agt.drv [driver] ip1 = 92, ip2 = 70
UVM_INFO base_seq.sv(10) @ 15: uvm_test_top.env_o.agt.seqr@@bseq [base_seq] Base seq: Inside Body
UVM_INFO driver.sv(20) @ 15: uvm_test_top.env_o.agt.drv [driver] ip1 = 4, ip2 = 62
----------------------------------------------------------------------------------------------------------
UVM_INFO scoreboard.sv(28) @ 18: uvm_test_top.env_o.sb [scoreboard] Matched: ip1 = 92, ip2 = 70, out = 162
----------------------------------------------------------------------------------------------------------
UVM_INFO base_seq.sv(10) @ 20: uvm_test_top.env_o.agt.seqr@@bseq [base_seq] Base seq: Inside Body
UVM_INFO driver.sv(20) @ 20: uvm_test_top.env_o.agt.drv [driver] ip1 = 57, ip2 = 60
UVM_INFO base_seq.sv(10) @ 25: uvm_test_top.env_o.agt.seqr@@bseq [base_seq] Base seq: Inside Body
UVM_INFO driver.sv(20) @ 25: uvm_test_top.env_o.agt.drv [driver] ip1 = 47, ip2 = 1
----------------------------------------------------------------------------------------------------------
UVM_INFO scoreboard.sv(28) @ 26: uvm_test_top.env_o.sb [scoreboard] Matched: ip1 = 57, ip2 = 60, out = 117
----------------------------------------------------------------------------------------------------------
UVM_INFO base_seq.sv(10) @ 30: uvm_test_top.env_o.agt.seqr@@bseq [base_seq] Base seq: Inside Body
UVM_INFO driver.sv(20) @ 30: uvm_test_top.env_o.agt.drv [driver] ip1 = 74, ip2 = 84
----------------------------------------------------------------------------------------------------------
UVM_INFO scoreboard.sv(28) @ 34: uvm_test_top.env_o.sb [scoreboard] Matched: ip1 = 47, ip2 = 1, out = 48
----------------------------------------------------------------------------------------------------------
UVM_INFO base_seq.sv(10) @ 35: uvm_test_top.env_o.agt.seqr@@bseq [base_seq] Base seq: Inside Body
UVM_INFO driver.sv(20) @ 35: uvm_test_top.env_o.agt.drv [driver] ip1 = 42, ip2 = 70
UVM_INFO base_seq.sv(10) @ 40: uvm_test_top.env_o.agt.seqr@@bseq [base_seq] Base seq: Inside Body
UVM_INFO driver.sv(20) @ 40: uvm_test_top.env_o.agt.drv [driver] ip1 = 48, ip2 = 36
----------------------------------------------------------------------------------------------------------
UVM_INFO scoreboard.sv(28) @ 42: uvm_test_top.env_o.sb [scoreboard] Matched: ip1 = 42, ip2 = 70, out = 112
----------------------------------------------------------------------------------------------------------
UVM_INFO base_seq.sv(10) @ 45: uvm_test_top.env_o.agt.seqr@@bseq [base_seq] Base seq: Inside Body
UVM_INFO driver.sv(20) @ 45: uvm_test_top.env_o.agt.drv [driver] ip1 = 91, ip2 = 40
----------------------------------------------------------------------------------------------------------
UVM_INFO scoreboard.sv(28) @ 50: uvm_test_top.env_o.sb [scoreboard] Matched: ip1 = 91, ip2 = 40, out = 131
----------------------------------------------------------------------------------------------------------
UVM_INFO base_seq.sv(10) @ 50: uvm_test_top.env_o.agt.seqr@@bseq [base_seq] Base seq: Inside Body
UVM_INFO driver.sv(20) @ 50: uvm_test_top.env_o.agt.drv [driver] ip1 = 75, ip2 = 55
UVM_INFO base_test.sv(25) @ 50: uvm_test_top [base_test] End of testcase