Systemverilog（綠皮書）第九章——功能覆蓋率（三）數據採樣

covergroup CovPort;
    options.auto_bin_max = 8;    //所有的coverpoint auto_bin數量是8
    coverpoint tr.port
        {    option.auto_bin_max = 2}    //特定的covepoint auto_bin數量2
    endgroup

covergroup CovKind;
    coverpoint tr.kind{
        bins zero = {0};    //1個倉代表kind==0
        bins lo = {[1:3] , 5};    //1個倉代表1:3和5
        bins hi[] = {[8:$]};      //8個獨立的倉代表8：15
        bins misc = default;      //1個倉代表剩餘所有值
}        //沒有分號
endgroup

注意coverpoint定義使用{ }而不是begin...end大括號結尾沒帶分號，和end一樣。 

covergroup CoverPort;
    coverpoint port iff
        (!bus_if.reset);    //滿足條件纔可以採樣
    endgroup

initial begin
    CovPort ck = new();
    #1ns;
    ck.stop();                //關掉，任何採樣都不起作用
    bus_if.reset = 1;
    #100ns bus_if.reset = 0;
    ck.reset();
    ...
end

針對任何一個covergoup實例，都可以進行使能採樣。 不同的coverpoint可以設置if的條件。

covergroup CoverPort;
    coverpoint port{
        (bins t1 = (0 => 1),(0 => 2),(0 => 3));
}
endgroup

bit [2:0] port;
covergroup CoverPort;
    coverpoint port{
        wildcsrd bins even = {3'b??0};
        wildcsrd bins odd= {3'b??1};        
}
endgroup

bit [2:0] low_ports_0_5;    //只使用數值0-5
covergroup CoverPort;
    coverpoint low_ports_0_5{
        ignore_bins hi = {[6:7]};    //忽略數值6-7
}
endgroup

bit [2:0] low_ports_0_5;    //只是用數值0-5
covergroup CoverPort;
    coverpoint low_ports_0_5{
        illegal_bins hi    {[6:7]};    //如果出現6-7便會報錯
}
endgroup

class Transaction;
    rand bit [3:0] kind;
    rand bit [2:0] port;
endclass
Transaction tr;
covergroup CovPort;
    kind: coverpoint tr.kind;
    kind: coverpoint tr.port;
    cross kind, port;
endgroup

covergroup Covport;
    port: coverpoint tr.port
        {bins port[] = {[0:$]};    //0-8個bin
}
    kind:coverpoint tr.kind {    //kind11個bin
        bins zero = {0};
        bins lo = {[1:3]}；
        bins hi[] = {[8:$]};
        bins misc = default;
}

cross kind, port{
    ignore_bins hi = binsof(port) intersect{7};    對於port來說爲7時和kind所有組合都排除
    ignore_bins md = binsof(port) intersect{0} && binsof(port) intersect{9:11}; 
    ignore_bins lo = binsof(kind.lo) ;    
}
endgroup

class Transaction;
    rand bit a,b;
endclass

covergroup CrossBinName;
    a: coverpoint tr.a
        {bins a0 = {0};
         bins a1 = {1};
         option.weight = 0;}        //不計算覆蓋率
    b: coverpoint t.b
        { bins b0 = {0};
          bins b1 = {1};
          option.weight = 0;}        //不計算覆蓋率
    ab: cross a,b
{ bins a0b0 = binsof(a.a0) && binsof(b.b0);    //指定一個狀態
    binsof(b.b0);
    bins a1b0 = binsif(a.a1) && binsof(b.b0);
    bina b1 = binsof(b.b1);}
endgroup