method()

The proper context for calling a regular method depends on whether the method returns a value or not.If the method returns a value, it is an expression and can be called from any context where an expression is valid.

If the method does not return a value, it is an action and can be called from any context where an action is valid.

  1 <'

  2 define HIGH 100;

  3 define LOW  50;

  4 struct memory_gen {

  5      ! err_cnt : int;

  6      ! war_cnt : int;

  7     // Define a event for posedge of clock

  8     event pos_clk is rise('top.clk')@sim;

  9

 10     // Define a method to check valid address

 11     addr_valid(addr : byte ):bool is {

 12       // Check if address is between HIGH and LOW value

 13       // Wait for one cycle and drive command

 14       if ((addr < LOW) || (addr > HIGH)) {

 15         return FALSE;

 16       } else {

 17         return TRUE;

 18       };

 19     };

 20

 21     // This method prints the error and warning count

 22     print_status() is {

 23       outf("Number of Warnings : %d",war_cnt);

 24       outf("Number of Errors   : %d",err_cnt);

 25     };

 26

 27    // We use this TCM to generate commands,drive them

 28    // and call out methods

 29    mem_txgen()@pos_clk is {

 30      var addr : byte;

 31      // Repeat (NO_COMMANDS)

 32        // generate write/read commands

 33        // Check address

 34        if (addr_valid(addr)) {

 35          // Drive to DUT

 36        } else {

 37          out ("address is not valid, skipping driver");

 38        };

 39      // End repeat

 40      // Call the status method

 41      print_status();

 42      // Stop simulation

 43    };

 44 };

 45 '>

 

In some cases you may want to call a value-returning method without using the value that is returned. To do this, you can use the compute action.

 

  1 <'

  2 define HIGH 100;

  3 define LOW  50;

  4 define ERR_LIMIT 200;

  5 struct memory_gen {

  6      ! err_cnt : int;

  7      ! war_cnt : int;

  8     // Define a event for posedge of clock

  9     event pos_clk is rise('top.clk')@sim;

 10

 11     // Define a method to check valid address

 12     addr_valid(addr : byte ):bool is {

 13       // Check if address is between HIGH and LOW value

 14       // Wait for one cycle and drive command

 15       if ((addr < LOW) || (addr > HIGH)) {

 16         return FALSE;

 17       } else {

 18         return TRUE;

 19       };

 20     };

 21

 22     // This method prints the error and warning count

 23     print_status():bool is {

 24       outf("Number of Warnings : %d",war_cnt);

 25       outf("Number of Errors   : %d",err_cnt);

 26       if (err_cnt >= ERR_LIMIT) {

 27         return FALSE;

 28       } else {

 29         return TRUE;

 30       };

 31     };

 32

 33    // We use this TCM to generate commands,drive them

 34    // and call out methods

 35    mem_txgen()@pos_clk is {

 36      var addr : byte;

 37      // Repeat (NO_COMMANDS)

 38        // generate write/read commands

 39        // Check address

 40        if (addr_valid(addr)) {

 41          // Drive to DUT

 42        } else {

 43          out ("address is not valid, skipping driver");

 44        };

 45      // End repeat

 46      // Call the status method, Since it returns a value

 47      // Which is no use to us, we use 'compute'

 48      compute print_status();

 49      // Stop simulation

 50    };

 51 };

 

return

Returns immediately from the current method to the method that called it. The execution of the calling method then continues.

It is not always necessary to provide a return action. When a value returning method ends without a return action, the value of result is returned. Any actions that follow a return action in the method definition are ignored. Actions placed in a method extension are performed before the return is executed.

 

  1 <'

  2 define HIGH 100;

  3 define LOW  50;

  4 define ERR_LIMIT 200;

  5 struct memory_gen {

  6      ! err_cnt : int;

  7      ! war_cnt : int;

  8     // Define a event for posedge of clock

  9     event pos_clk is rise('top.clk')@sim;

 10

 11     // Define a method to check valid address

 12     // This method shows how to use result

 13     addr_valid(addr : byte ):bool is {

 14       // Check if address is between HIGH and LOW value

 15       // Wait for one cycle and drive command

 16       if ((addr < LOW) || (addr > HIGH)) {

 17         result =  FALSE;

 18       } else {

 19         result = TRUE;

 20       };

 21     };

 22

 23     // This method prints the error and warning count

 24     // This method shows how to use return

 25     print_status():bool is {

 26       outf("Number of Warnings : %d",war_cnt);

 27       outf("Number of Errors   : %d",err_cnt);

 28       if (err_cnt >= ERR_LIMIT) {

 29         return FALSE;

 30       } else {

 31         return TRUE;

 32       };

 33     };

 34

 35     // This method shows how to use return without a value

 36     print_parity(data:byte, addr:byte) is {

 37       if (addr_valid(addr)) {

 38         var parity : bit = data[7:7]^data[6:6]^data[5:5]^

 39                            data[4:4]^data[3:3]^data[2:2]^

 40                            data[1:1]^data[0:0];

 41         outf ("Parity of data is %b\n", parity);

 42       } else {

 43         return;

 44         // This will not be executed

 45         outf ("Address is not valid");

 46       };

 47     };

 48

 49    // We use this TCM to generate commands,drive them

 50    // and call out methods

 51    mem_txgen()@pos_clk is {

 52      var addr : byte;

 53      // Repeat (NO_COMMANDS)

 54        // generate write/read commands

 55        // Check address

 56        if (addr_valid(addr)) {

 57          // Drive to DUT

 58        } else {

 59          out ("address is not valid, skipping driver");

 60        };

 61      // End repeat

 62      // Call the status method, Since it returns a value

 63      // Which is no use to us, we use 'compute'

 64      compute print_status();

 65      // Stop simulation

 66    };

 67 };

 68 '>

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