【课后习题答案】SystemVerilog for Verification 3rd Edition第五章（绿皮书第三版）

1 解答class MemTrans; // a. 8位logic类型的data_in logic [7:0] data_in; // b. 4位logic类型的address logic [3:0] address; // c. 打印data_in和address的void函数 function void print(); $display(data_in 0x%h, address 0x%h, data_in, address); endfunction // 默认无参构造函数 function new(); endfunction endclass // 测试逻辑 program automatic test_MemTrans; initial begin MemTrans mt new(); // 构造时自动初始化为0 mt.print(); // 输出data_in 0x00, address 0x0 end endprogram说明定义MemTrans类包含指定成员与print方法通过program中的initial块完成对象实例化、赋值与方法调用。2 解答class MemTrans; logic [7:0] data_in; logic [3:0] address; function void print(); $display(data_in 0x%h, address 0x%h, data_in, address); endfunction // 自定义构造函数初始化data_in和address为0 function new(); data_in 8h0; address 4h0; endfunction endclass program automatic test_MemTrans; initial begin MemTrans mt new(); // 构造时自动初始化为0 mt.print(); // 输出data_in 0x00, address 0x0 end endprogram说明在new构造函数中显式初始化成员变量对象实例化时自动完成零值初始化。3 解答class MemTrans; logic [7:0] data_in; logic [3:0] address; function void print(); $display(data_in 0x%h, address 0x%h, data_in, address); endfunction // 带默认参数的构造函数 function new(input logic [7:0] data_in 8h0, input logic [3:0] address 4h0); this.data_in data_in; this.address address; endfunction endclass program automatic test_MemTrans; initial begin // a. 创建两个对象 // b. 第一个对象按名传参address2 MemTrans mt1 new(.address(4h2)); // c. 第二个对象按名传参data_in3、address4 MemTrans mt2 new(.data_in(8h3), .address(4h4)); // 打印验证 $display(mt1:); mt1.print(); // 输出data_in 0x00, address 0x2 $display(mt2:); mt2.print(); // 输出data_in 0x03, address 0x4 end endprogram说明构造函数参数添加默认值实例化时通过.参数名(值)语法实现灵活传参初始化。4 解答class MemTrans; logic [7:0] data_in; logic [3:0] address; function void print(); $display(data_in 0x%h, address 0x%h, data_in, address); endfunction function new(input logic [7:0] data_in 8h0, input logic [3:0] address 4h0); this.data_in data_in; this.address address; endfunction endclass program automatic test_MemTrans; initial begin MemTrans mt1 new(.address(4h2)); MemTrans mt2 new(.data_in(8h3), .address(4h4)); // a. 构造后修改mt1的address为4hF mt1.address 4hF; // b. 打印两个对象信息 $display(mt1 after modification:); mt1.print(); // 输出data_in 0x00, address 0xF $display(mt2:); mt2.print(); // 输出data_in 0x03, address 0x4 // c. 显式释放mt2 delete mt2; $display(mt2 has been deallocated.); end endprogram说明构造后直接赋值修改成员变量通过delete关键字显式释放对象句柄。5 解答class MemTrans; logic [7:0] data_in; logic [3:0] address; // 静态变量保存最近创建对象的address初始值 static logic [3:0] last_address; function void print(); $display(data_in 0x%h, address 0x%h, data_in, address); endfunction function new(input logic [7:0] data_in 8h0, input logic [3:0] address 4h0); this.data_in data_in; this.address address; // 构造时更新静态变量静态变量属于类需用“类名.变量名”访问 MemTrans.last_address this.address; endfunction endclass program automatic test_MemTrans; initial begin MemTrans mt1 new(.address(4h2)); MemTrans mt2 new(.data_in(8h3), .address(4h4)); mt1.address 4hF; // 打印最近创建对象的address初始值 $display(Current last_address 0x%h, MemTrans.last_address); // 输出0x4 end endprogram说明static变量属于类非对象每次实例化对象时构造函数会更新其值通过 “类名。静态变量” 访问。6 解答class MemTrans; logic [7:0] data_in; logic [3:0] address; static logic [3:0] last_address; function void print(); $display(data_in 0x%h, address 0x%h, data_in, address); endfunction function new(input logic [7:0] data_in 8h0, input logic [3:0] address 4h0); this.data_in data_in; this.address address; MemTrans.last_address this.address; endfunction // 静态方法打印静态变量last_address静态方法属于类无需实例化即可调用 static function void print_last_address(); $display(last_address 0x%h, MemTrans.last_address); endfunction endclass program automatic test_MemTrans; initial begin MemTrans mt1 new(.address(4h2)); MemTrans mt2 new(.data_in(8h3), .address(4h4)); mt1.address 4hF; // 调用静态方法直接通过类名调用 MemTrans.print_last_address(); // 输出last_address 0x4 end endprogram说明static方法属于类无需实例化对象直接通过 “类名。方法名” 调用内部可访问类的静态成员。7 解答class PrintUtilities; // 打印4位数据的方法 function void print_4(input string name, input [3:0] val_4bits); $display(%t: %s %h, $time, name, val_4bits); endfunction // 打印8位数据的方法 function void print_8(input string name, input [7:0] val_8bits); $display(%t: %s %h, $time, name, val_8bits); endfunction endclass class MemTrans; bit [7:0] data_in; bit [3:0] address; PrintUtilities print_utils; // 组合PrintUtilities类的句柄 // 构造函数实例化PrintUtilities对象 function new(); print_utils new(); endfunction // 补全print_all调用PrintUtilities的方法打印成员 function void print_all(); print_utils.print_8(data_in, this.data_in); // 打印8位data_in print_utils.print_4(address, this.address); // 打印4位address endfunction endclass说明MemTrans通过组合PrintUtilities对象复用其打印方法print_all方法封装了成员变量的打印逻辑。8 解答package automatic my_package; // 定义Transaction类面向对象的事务类 class Transaction; function new(); $display(Transaction object created.); endfunction endclass endpackage program automatic test; import my_package::*; // 导入包中的Transaction类 initial begin // 声明5个Transaction句柄的数组 Transaction tr_array[5]; // 调用generator任务创建对象 generator(tr_array); end // 补全任务头接收Transaction数组的引用 task generator(ref Transaction tr_array[]); foreach(tr_array[i]) begin // 为每个数组元素实例化Transaction对象 tr_array[i] new(); // 调用transmit任务传递对象 transmit(tr_array[i]); end endtask // 处理Transaction对象的transmit任务 task transmit(Transaction tr); $display(Transmitting Transaction object.); endtask : transmit endprogram说明通过数组管理多个Transaction对象generator任务负责对象实例化transmit任务负责对象的传递与处理。9 解答package automatic my_package; // 假设的Statistics类深拷贝 class Statistics; int cnt; // 统计计数器 function new(); cnt 0; endfunction // Statistics的copy方法 function Statistics copy(); copy new(); copy.cnt this.cnt; endfunction endclass class MemTrans; bit [7:0] data_in; bit [3:0] address; Statistics stats; // 组合Statistics类的句柄 // 构造函数初始化成员 function new(); data_in 3; address 5; stats new(); endfunction // 补全MemTrans的copy方法实现深拷贝 function MemTrans copy(); copy new(); // 创建新的MemTrans对象 // 复制基本类型成员 copy.data_in this.data_in; copy.address this.address; // 调用Statistics的copy方法复制stats深拷贝避免资源共享 copy.stats this.stats.copy(); endfunction endclass endpackage // 演示copy方法的测试逻辑 program automatic test_copy; import my_package::*; initial begin // 创建原对象并修改stats成员 MemTrans orig new(); orig.stats.cnt 10; // 调用copy方法生成新对象 MemTrans copy_obj orig.copy(); // 验证拷贝结果 $display(Original: data_in0x%h, address0x%h, stats.cnt%0d, orig.data_in, orig.address, orig.stats.cnt); $display(Copied: data_in0x%h, address0x%h, stats.cnt%0d, copy_obj.data_in, copy_obj.address, copy_obj.stats.cnt); // 输出 // Original: data_in0x03, address0x5, stats.cnt10 // Copied: data_in0x03, address0x5, stats.cnt10 end endprogram说明copy方法需区分 “基本类型”直接赋值与 “类对象”调用其copy方法实现深拷贝避免浅拷贝导致的成员共享问题。