Systemverilog（绿皮书）第九章——功能覆盖率（三）数据采样

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

covergroup CovKind;
    coverpoint tr.kind{
        bins zero = {0};    //1个仓代表kind==0
        bins lo = {[1:3] , 5};    //1个仓代表1:3和5
        bins hi[] = {[8:$]};      //8个独立的仓代表8：15
        bins misc = default;      //1个仓代表剩余所有值
}        //没有分号
endgroup

注意coverpoint定义使用{ }而不是begin...end大括号结尾没带分号，和end一样。 

covergroup CoverPort;
    coverpoint port iff
        (!bus_if.reset);    //满足条件才可以采样
    endgroup

initial begin
    CovPort ck = new();
    #1ns;
    ck.stop();                //关掉，任何采样都不起作用
    bus_if.reset = 1;
    #100ns bus_if.reset = 0;
    ck.reset();
    ...
end

针对任何一个covergoup实例，都可以进行使能采样。 不同的coverpoint可以设置if的条件。

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;    //只使用数值0-5
covergroup CoverPort;
    coverpoint low_ports_0_5{
        ignore_bins hi = {[6:7]};    //忽略数值6-7
}
endgroup

bit [2:0] low_ports_0_5;    //只是用数值0-5
covergroup CoverPort;
    coverpoint low_ports_0_5{
        illegal_bins hi    {[6:7]};    //如果出现6-7便会报错
}
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:$]};    //0-8个bin
}
    kind:coverpoint tr.kind {    //kind11个bin
        bins zero = {0};
        bins lo = {[1:3]}；
        bins hi[] = {[8:$]};
        bins misc = default;
}

cross kind, port{
    ignore_bins hi = binsof(port) intersect{7};    对于port来说为7时和kind所有组合都排除
    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;}        //不计算覆盖率
    b: coverpoint t.b
        { bins b0 = {0};
          bins b1 = {1};
          option.weight = 0;}        //不计算覆盖率
    ab: cross a,b
{ bins a0b0 = binsof(a.a0) && binsof(b.b0);    //指定一个状态
    binsof(b.b0);
    bins a1b0 = binsif(a.a1) && binsof(b.b0);
    bina b1 = binsof(b.b1);}
endgroup