APB Coverage

[mahadevaswamy05]

• Here we are exploring the APB Coverage for each signal called address, data, write, read

[mahadevaswamy05]

-The code is for the coverage uut file

• we have a coverage file in which the class name(apb_coverage) is extended from the uvm_subscriber by parametrizing the transaction class name.
• In this code only we'll write bins for each signal.
• And using the coverage name we are triggering the covergroup. for example cg.sample();

apb_coverage

```systemverilog `ifndef __APB_COVERAGE_SV__ `define __APB_COVERAGE_SV__ `include "uvm_macros.svh" `include "apb_xaction.sv" import uvm_pkg::*; class apb_coverage extends uvm_subscriber #(apb_xaction); `uvm_component_utils(apb_coverage) local apb_xaction sampled_obj; covergroup cg; addr_min_cp : coverpoint sampled_obj.addr { bins min = { 0 }; } addr_max_cp : coverpoint sampled_obj.addr { bins max = { 'hfc }; } addr_bins_cp : coverpoint sampled_obj.addr { bins b [16] = { [1:'hf8] }; } data_min_cp : coverpoint sampled_obj.data { bins min = { 0 }; } data_max_cp : coverpoint sampled_obj.data { bins max = { 'hffff_ffff }; } data_bins_cp : coverpoint sampled_obj.data { bins b [32] = { [1:'hffff_fffe] }; } kind_cp : coverpoint sampled_obj.kind; option.per_instance = 1; endgroup; function new(string name = "apb_coverage", uvm_component parent = null); super.new(name, parent); cg = new(); endfunction function void write(apb_xaction t); sampled_obj = t; cg.sample(); endfunction function uvm_sequence_item get_sampled_obj(); return sampled_obj; endfunction endclass `endif ```

[mahadevaswamy05]

2. -The code is for the coverage unit test template file

apb_coverage_unit_test

```systemverilog `include "svunit_defines.svh" `include "apb_coverage.sv" module apb_coverage_unit_test; import svunit_pkg::svunit_testcase; import svunit_uvm_mock_pkg::*; string name = "apb_coverage_ut"; svunit_testcase svunit_ut; //=================================== // This is the UUT that we're // running the Unit Tests on //=================================== apb_coverage my_apb_coverage; //=================================== // Build //=================================== function void build(); svunit_ut = new(name); my_apb_coverage = new({ name , "::my_apb_coverage" }, null); //----------------------- // deactivate by default //----------------------- svunit_deactivate_uvm_component(my_apb_coverage); endfunction //=================================== // Setup for running the Unit Tests //=================================== task setup(); svunit_ut.setup(); //---------------------- // activate for testing //---------------------- svunit_activate_uvm_component(my_apb_coverage); //--------------------- // start the component //--------------------- svunit_uvm_test_start(); endtask //=================================== // Here we deconstruct anything we // need after running the Unit Tests //=================================== task teardown(); svunit_ut.teardown(); //-------------------- // stop the component //-------------------- svunit_uvm_test_finish(); //--------------------------------------- // deactivate at the end of unit testing //--------------------------------------- svunit_deactivate_uvm_component(my_apb_coverage); endtask //=================================== // All tests are defined between the // SVUNIT_TESTS_BEGIN/END macros // // Each individual test must be // defined between `SVTEST(_NAME_) // `SVTEST_END // // i.e. // `SVTEST(mytest) // // `SVTEST_END //=================================== `SVUNIT_TESTS_BEGIN //------------------------------------- // Test: write_method /// // verify the write_method sets the // local obj to be sampled and that // the addr_min_cp and data_min_cp are // sampled correctly //------------------------------------- `SVTEST(write_method) apb_xaction a, b; a = apb_xaction::type_id::create(); void'(a.randomize() with { addr == 0; data == 0; kind == WRITE; }); my_apb_coverage.write(a); $cast(b, my_apb_coverage.get_sampled_obj()); `FAIL_IF(!a.compare(b)); //not never same `FAIL_IF(my_apb_coverage.cg.addr_min_cp.get_coverage() != 100); //100 % `FAIL_IF(my_apb_coverage.cg.data_min_cp.get_coverage() != 100); //100 `FAIL_IF(my_apb_coverage.cg.kind_cp.get_coverage() != 50); my_apb_coverage.cg.start(); `SVTEST_END //------------------------------------- // Test: addr_max_cp // // verify the bin for addr == fc //------------------------------------- `SVTEST(addr_max_cp) apb_xaction a; a = apb_xaction::type_id::create(); void'(a.randomize() with { addr == 'hfc; data == 0; kind == WRITE; }); my_apb_coverage.write(a); `FAIL_IF(my_apb_coverage.cg.addr_max_cp.get_coverage() != 100); `SVTEST_END // Test: addr_bins_cp //------------------------------------- // verify 16 bins for addr between // 1 //------------------------------------- // 1:'hf8 `SVTEST(addr_bins_cp) apb_xaction a; a = apb_xaction::type_id::create(); void'(a.randomize() with { addr == 1; data == 0; kind == WRITE; }); my_apb_coverage.write(a); `FAIL_IF($rtoi(my_apb_coverage.cg.addr_bins_cp.get_coverage()) != (100/16)); for (int i=1; i<16; i+=1) begin a.addr += 'hf8/16; my_apb_coverage.write(a); `FAIL_IF($rtoi(my_apb_coverage.cg.addr_bins_cp.get_coverage()) != ((i+1) * 100/16)); end `FAIL_IF(my_apb_coverage.cg.addr_bins_cp.get_coverage() != 100); `SVTEST_END //------------------------------------- // Test: data_max_cp // // verify the bin for data == ffff_ffff //------------------------------------- `SVTEST(data_max_cp) apb_xaction a; a = apb_xaction::type_id::create(); void'(a.randomize() with { data == 'hffff_ffff; kind == WRITE; }); my_apb_coverage.write(a); `FAIL_IF(my_apb_coverage.cg.data_max_cp.get_coverage() != 100); `SVTEST_END //------------------------------------- // Test: data_bins_cp // // verify 32 bins for data between // 1:'hffff_fffe //------------------------------------- `SVTEST(data_bins_cp) apb_xaction a; a = apb_xaction::type_id::create(); void'(a.randomize() with { data == 1; kind == WRITE; }); my_apb_coverage.write(a); `FAIL_IF($rtoi(my_apb_coverage.cg.data_bins_cp.get_coverage()) != (100/32)); for (int i=1; i<32; i+=1) begin a.data += 'hffff_fffe/32; my_apb_coverage.write(a); `FAIL_IF($rtoi(my_apb_coverage.cg.data_bins_cp.get_coverage()) != ((i+1) * 100/32)); end `FAIL_IF(my_apb_coverage.cg.data_bins_cp.get_coverage() != 100); `SVTEST_END //------------------------------------- // Test: kind_cp // // verify the kind for read and write //------------------------------------- `SVTEST(kind_cp) apb_xaction a; my_apb_coverage.cg.kind_cp.start(); a = apb_xaction::type_id::create(); void'(a.randomize() with { kind == READ; } ); my_apb_coverage.write(a); `FAIL_IF(my_apb_coverage.cg.kind_cp.get_coverage() != 100); `SVTEST_END `SVUNIT_TESTS_END endmodule ```

[mahadevaswamy05]

3 Now we are exploring each test in the apb_coverage_unit_test

• we have declared the handle for the transaction, for example, apb_xaction a, b;
• In the below code, we are writing the coverage test for the write_method in the unit_test_template file.
• we'll do the randomization using the inline constraint to pass some values as data = 0, addr = 0, kind = write.
• and we declared the handle for the coverage(uut), for example apb_coverage my_apb_coverage.
• using the coverage handle we'll call the write method logic and pass the argument as a transaction_handle, for example, my_apb_coverage.write(a);
• $cast method doing casting of the transaction handles of the b.
• and checking whether a is equal to b or not, if a is not equal to b then the test will fail. because we are using FAIL_IF(!a.compare(b)); but Here a and b are the same that's why, the test will set the status as passed.
• In the second FAIL_IF condition we are checking addr signals coverage, Here given the condition FAIL_IF(my_apb_coverage.cg.addr_min_cp.get_coverage() != 100); is False because we are checking !=100 but it's equal to 100% that's why the test will set the status as passed.
• In the Third FAIL_IF condition we are checking data signals coverage, Here given the condition FAIL_IF(my_apb_coverage.cg.data_min_cp.get_coverage() != 100); is False because we are checking !=100 but it's equal to 100% that's why the test will set the status as passed.
• In the fourth FAIL_IF condition we are checking kind signals coverage (It indicates the write happens or not) FAIL_IF(my_apb_coverage.cg.kind_cp.get_coverage() != 50); are checking !=50 but it's equal to 50% that's why the test will set the status as passed.
• At the end, we'll start the coverage using the coverage start method.

  `SVTEST(write_method)
    apb_xaction a, b;

    a = apb_xaction::type_id::create();
    void'(a.randomize() with { addr == 0;
                               data == 0;
                               kind == WRITE;
                             });

    my_apb_coverage.write(a);

    $cast(b, my_apb_coverage.get_sampled_obj());
    `FAIL_IF(!a.compare(b)); //not never same
    `FAIL_IF(my_apb_coverage.cg.addr_min_cp.get_coverage() != 100); //100 %
    `FAIL_IF(my_apb_coverage.cg.data_min_cp.get_coverage() != 100); //100
    `FAIL_IF(my_apb_coverage.cg.kind_cp.get_coverage() != 50);

    my_apb_coverage.cg.start();
  `SVTEST_END

- The below snippet for the uut file coverage code.

• In the below code we are creating one bin for the data signal and the same as the address signals also. and the kind signal will create 2 bins.

data_min_cp :
      coverpoint sampled_obj.data {
        bins min = { 0 };
      }
addr_min_cp :
      coverpoint sampled_obj.addr {
        bins min = { 0 };
      }
kind_cp :
      coverpoint sampled_obj.kind;

- Output for this test

• Using this below command we are running the particular test. runSVUnit -uvm -define CLK_PERIOD=5ns --filter apb_coverage_ut.write_method -s questa

• you can see the below test is getting passed and all values are getting covered.

[mahadevaswamy05]

4. Now we are exploring second test in the apb_coverage_unit_test

• In the below snippet for the coverage for the address signal, Here we are writing the max value to the address signal and checking whether the max value is covered or not.
• We are giving the value to the address signal by using the randomization with inline constraint and value asaddr = 'hfc , data = 0, kind = write.
• Using the coverage handle we'll call the write method logic and pass the argument as a transaction_handle, for example, my_apb_coverage.write(a);
• In the FAIL_IF condition we are checking address signals coverage, Here given the condition FAIL_IF(my_apb_coverage.cg.addr_max_cp.get_coverage() != 100); is False because we are checking !=100 but it's equal to 100% that's why the test will set the status as passed.

`SVTEST(addr_max_cp)
    apb_xaction a;

    a = apb_xaction::type_id::create();
    void'(a.randomize() with { addr == 'hfc;
                               data == 0;
                               kind == WRITE;
                             });

    my_apb_coverage.write(a);

    `FAIL_IF(my_apb_coverage.cg.addr_max_cp.get_coverage() != 100);
    `SVTEST_END

• The below snippet for the uut file coverage code
• In the below code we are creating the only one bin for the address signal and passing the value as'hfc

  
  addr_max_cp :
    coverpoint sampled_obj.addr {
      bins max = { 'hfc };
    }

**- Output for this test**
- Using this below command we are running the particular test.

`runSVUnit -uvm -define CLK_PERIOD=5ns --filter apb_coverage_ut.addr_max_cp -s questa
`
- you can see the below test output picture it's getting passed and the address signal value is getting covered.

![image](https://github.com/mbits-mirafra/axi4_avip/assets/106074838/3133445a-4217-468d-8939-e7cc10e289f9)

[mahadevaswamy05]

5. Now we are exploring the third test in the apb_coverage_unit_test

• In the below snippet for the coverage for the address signal, Here we are writing the value to the address signal and checking whether it the covered or not we are checking.
• We are giving the value to the address signal by using the randomization with inline constraint and value as addr = 1, data = 0, kind = write.
• Using the coverage handle we'll call the write method logic and pass the argument as a transaction_handle, for example, my_apb_coverage.write(a);
• $rtoi converts real values to an integer type by truncating the real value (for example,123.45 becomes 123)
• In this coverage, it will create the 16 bins then the test will get passed otherwise it will show the failed message.

• In the last FAIL_IF condition we are checking address signals coverage, Here given the condition FAIL_IF(my_apb_coverage.cg.addr_bins_cp.get_coverage() != 100); is False because we are checking !=100 but it's equal to 100% that's why the test will set the status as passed.

  `SVTEST(addr_bins_cpi)
  apb_xaction a;
  
  a = apb_xaction::type_id::create();
  void'(a.randomize() with { addr == 1;
                             data == 0;
                             kind == WRITE;
                           });
  
  my_apb_coverage.write(a);
  
  `FAIL_IF($rtoi(my_apb_coverage.cg.addr_bins_cp.get_coverage()) != (100/16));
  
  for (int i=1; i<16; i+=1) begin
    a.addr += 'hf8/16;
  
    my_apb_coverage.write(a);
  
    `FAIL_IF($rtoi(my_apb_coverage.cg.addr_bins_cp.get_coverage()) != ((i+1) * 100/16));
  end
  
  `FAIL_IF(my_apb_coverage.cg.addr_bins_cp.get_coverage() != 100);
  
  `SVTEST_END

  - The below snippet for the uut file coverage code

• In the below code we are creating the 16 bins for the address signal and passing the value range from 1 to 248.

 addr_bins_cp :
      coverpoint sampled_obj.addr {
        bins b [16] = { [1:'hf8] };
      }

• Using this below command we are running the particular test.

runSVUnit -uvm -define CLK_PERIOD=5ns --filter apb_coverage_ut.addr_bins_cpi -s questa

• You can see the test output picture it's getting passed and the address signal created all 16 bins here.

[mahadevaswamy05]

6.. Now we are exploring the fourth test in the apb_coverage_unit_test

• We have declared the handle for the transaction, for example, apb_xaction a
• In the below snippet for the coverage of the data signal, we are writing the value to the data signal and checking whether it the covered or not we are checking.
• We are giving the value to the data signal by using the randomization with inline constraint and value as data = 'hffff_ffff, kind == WRITE;
• Using the coverage handle we'll call the write method logic and pass the argument as a transaction_handle, for example, my_apb_coverage.write(a);
• In the last FAIL_IF condition we are checking data signals coverage, Here given the condition FAIL_IF(my_apb_coverage.cg.data_max_cp.get_coverage() != 100); is False because we are checking !=100 but it's equal to 100% that's why the test will set the status as passed.

 `SVTEST(data_max_cp)
    apb_xaction a;

    a = apb_xaction::type_id::create();
    void'(a.randomize() with { data == 'hffff_ffff;
                               kind == WRITE;
                             });

    my_apb_coverage.write(a);

    `FAIL_IF(my_apb_coverage.cg.data_max_cp.get_coverage() != 100);

  `SVTEST_END

- The below snippet for the uut file coverage code

• In the below code we are creating only one bin for the data signal and passing the values as ffff_ffff.

 data_max_cp :
      coverpoint sampled_obj.data {
        bins max = { 'hffff_ffff };
      }

• Using this below command we are running the particular test.

runSVUnit -uvm -define CLK_PERIOD=5ns --filter apb_coverage_ut.data_max_cp -s questa

• You can see the test output picture it's getting passed and the data signal created a bin and that bin is hit for this number 65535.

[mahadevaswamy05]

7. Now we are exploring the fifth test in the apb_coverage_unit_test it's about read.

• We have declared the handle for the transaction, for example, apb_xaction a.
• In the below snippet for the coverage of the Read, we are writing the value to the kind signal and checking whether it the covered Read or not we are checking.
• We are giving the value to the kind signal by using the randomization with inline constraint and value as kind == read.
• Using the coverage handle we'll call the read method logic and pass the argument as a transaction_handle, for example, my_apb_coverage.write(a);
• In the last FAIL_IF condition we are checking kind signals coverage, Here given the condition FAIL_IF(my_apb_coverage.cg.kind_cp.get_coverage() != 50); is False because we are checking !=50 but it's equal to 50% that's why the test will set the status as passed.

`SVTEST(kind_cp)
    apb_xaction a;

    my_apb_coverage.cg.kind_cp.start();

    a = apb_xaction::type_id::create();
    void'(a.randomize() with { kind == READ; } );

    my_apb_coverage.write(a);

    `FAIL_IF(my_apb_coverage.cg.kind_cp.get_coverage() != 50);

  `SVTEST_END

• The below snippet for the uut file coverage code
• Kind signal will create one bin for this read logic.

  kind_cp :
 coverpoint sampled_obj.kind;

- Using the below command we are running the particular test.

runSVUnit -uvm -define CLK_PERIOD=5ns --filter apb_coverage_ut.kind_cp -s questa

[mahadevaswamy05]

-8. Using the below command we are the running the all test

runSVUnit -uvm -define CLK_PERIOD=5ns -s questa