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Controlling generation

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Hello, I have a query in generation. Suppose if i need to generate a field based on other field, For example class gen; rand rw_wr; rand data; endclass in the above code i want to generate data only when rw_wr = 1 if rw_wr = '0' data should not be generated. For the above scenario how to write the generation constraint. Sundar


Originally posted in cdnusers.org by sundar_80
Parents

  • Sundar,

    See the example below.

    module randData;

    class inData;

    rand bit rw_wr;
    rand int data;

    constraint order_mode { solve rw_wr before data ;}

    constraint dataConstraint {
    rw_wr == 0 -> data == 0;
    rw_wr == 1 -> data inside {[0:100]};
    }
    endclass

    inData iData = new(); // Create an object iData of class inData with
    // seedequal to 100.

    task generateRandomvalues;
    int success;
    success = iData.randomize();

    if (success == 1)
    $display("Randomized the class members");
    else
    $display("Randomization failed");
    endtask

    task displayVal;
    $display("Rd_Wr is %b",iData.rw_wr);
    $display("Data is %d",iData.data);
    endtask

    initial begin
    #10;
    generateRandomvalues;
    displayVal;
    #10;
    generateRandomvalues;
    displayVal;
    #10;
    generateRandomvalues;
    displayVal;
    #10;
    generateRandomvalues;
    displayVal;
    #10;
    generateRandomvalues;
    displayVal;
    #10;
    generateRandomvalues;
    displayVal;
    end
    endmodule

    Here's how the output looks like

    ncsim> run
    SVSEED default: 1
    Randomized the class members
    Rd_Wr is 0
    Data is 0
    Randomized the class members
    Rd_Wr is 0
    Data is 0
    Randomized the class members
    Rd_Wr is 1
    Data is 91
    Randomized the class members
    Rd_Wr is 1
    Data is 37
    Randomized the class members
    Rd_Wr is 1
    Data is 54
    Randomized the class members
    Rd_Wr is 1
    Data is 14
    ncsim: *W,RNQUIE: Simulation is complete.


    -Vivek.


    Originally posted in cdnusers.org by prasad_vc
Reply

  • Sundar,

    See the example below.

    module randData;

    class inData;

    rand bit rw_wr;
    rand int data;

    constraint order_mode { solve rw_wr before data ;}

    constraint dataConstraint {
    rw_wr == 0 -> data == 0;
    rw_wr == 1 -> data inside {[0:100]};
    }
    endclass

    inData iData = new(); // Create an object iData of class inData with
    // seedequal to 100.

    task generateRandomvalues;
    int success;
    success = iData.randomize();

    if (success == 1)
    $display("Randomized the class members");
    else
    $display("Randomization failed");
    endtask

    task displayVal;
    $display("Rd_Wr is %b",iData.rw_wr);
    $display("Data is %d",iData.data);
    endtask

    initial begin
    #10;
    generateRandomvalues;
    displayVal;
    #10;
    generateRandomvalues;
    displayVal;
    #10;
    generateRandomvalues;
    displayVal;
    #10;
    generateRandomvalues;
    displayVal;
    #10;
    generateRandomvalues;
    displayVal;
    #10;
    generateRandomvalues;
    displayVal;
    end
    endmodule

    Here's how the output looks like

    ncsim> run
    SVSEED default: 1
    Randomized the class members
    Rd_Wr is 0
    Data is 0
    Randomized the class members
    Rd_Wr is 0
    Data is 0
    Randomized the class members
    Rd_Wr is 1
    Data is 91
    Randomized the class members
    Rd_Wr is 1
    Data is 37
    Randomized the class members
    Rd_Wr is 1
    Data is 54
    Randomized the class members
    Rd_Wr is 1
    Data is 14
    ncsim: *W,RNQUIE: Simulation is complete.


    -Vivek.


    Originally posted in cdnusers.org by prasad_vc
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