**兩隻小豬**

1.    Why Are You Interested in This Role?

I have been working in the chip industry for over ten years and have all it takes to succeed in this role. This job’s description further fits my expertise. I have also always wanted to work for your company since my internship days, and therefore, it will be an honor if given a chance to do so. 我在芯片行業工作了十多年，擁有成功擔任這個角色所需的一切。這份工作的描述更符合我的專業知識。從實習開始，我也一直想為貴公司工作，因此，如果有機會這樣做，將是一種榮幸。

2.    Mention the Difference Between a Virtual and Pure Virtual Function in System Verilog

A virtual function allows the overriding of implementation of a function in a given derived class. Therefore, the base class doesn’t need to implement the virtual function. 0n the other hand, a pure virtual function only has the declaration and lacks any implementation. Therefore, any derivative class must implement the function. 虛函數允許覆蓋給定派生類中函數的實現。因此，基類不需要實現虛函數。 0n 另一方面，純虛函數只有聲明，沒有任何實現。因此，任何派生類都必須實現該功能。

3.    What Do You Understand by Semaphores? Do You Know When They Are Used?

A semaphore is used to control access to shared resources. One can view it as a bucket with several keys during its creation. Before any process that uses a semaphore can continue to execute, it must procure a key first from this bucket. Therefore, any process without a key must wait until the ones with procured keys give them back. This mechanism is therefore used for mutual exclusion, primary synchronization, and accessing control to shared resources. 信號量用於控制對共享資源的訪問。在創建過程中可以將其視為具有多個鍵的存儲桶。在任何使用信號量的進程可以繼續執行之前，它必須首先從這個桶中獲取一個密鑰。因此，任何沒有密鑰的進程都必須等到擁有密鑰的進程將它們歸還。因此，該機制用於互斥、主同步和對共享資源的訪問控制。

4.    Have You Interacted with Mailboxes? What Are They and Some of Their Uses?

A mailbox allows the exchange of a message between two processes. Usually, data is sent to the mailbox using one process and retrieved by the other. Placing and retrieving a message in a mailbox, therefore,  takes the support of two methods. There are two different types of mailboxes: bounded and unbounded. The unbounded mailbox has no size limit, whereas the bounded mailbox has a limited size limit set during its creation. 郵箱允許在兩個進程之間交換消息。通常，數據使用一個進程發送到郵箱並由另一個進程檢索。因此，在郵箱中放置和檢索消息需要兩種方法的支持。有兩種不同類型的郵箱：有界和無界。無界郵箱沒有大小限制，而有界郵箱在創建過程中設置了有限的大小限制。

5.    What Does a Virtual Interface Mean to You? Where Is It Used?

It is a variable that leads to an actual interface. A virtual interface provides a connection point that allows access to the signals in an interface via the virtual interface pointer. 它是一個通向實際界面的變量。虛擬接口提供了一個連接點，允許通過虛擬接口指針訪問接口中的信號。

6.    Explain the Concept of Factory and Factory Pattern

A factory (in object-oriented programming) is a function used to create different objects of a prototype. This happens when the different classes are registered with the factory, enabling the factory method to create objects of any registered class type by calling the corresponding constructor. Objects can also be created instead of calling the constructor method directly in a process known as factory pattern. It engages factory objects and allows for the use of polymorphism for object creation. 工廠（在面向對象編程中）是用於創建原型的不同對象的函數。當不同的類向工廠註冊時會發生這種情況，從而使工廠方法能夠通過調用相應的構造函數來創建任何註冊類類型的對象。也可以在稱為工廠模式的過程中創建對象，而不是直接調用構造函數方法。它使用工廠對象並允許使用多態性來創建對象。

7.    What Do You Understand by Callback?

Whenever a function calls another function that takes the first one as an argument, we get a callback. It is usually called when an event happens. It comes in handy in several applications in a verification testbench. Some of these include calling back a function to inject error on transactions sent from the driver, calling a function to drain pending transactions, and calling a coverage sample function in the event of a specific occurrence. 每當一個函數調用另一個以第一個作為參數的函數時，我們都會得到一個回調。它通常在事件發生時調用。它在驗證測試台中的多個應用程序中派上用場。其中一些包括回調函數以在從驅動程序發送的事務上註入錯誤，調用函數以排出掛起的事務，以及在發生特定事件時調用覆蓋率示例函數。

8.    What Kind of Strategies and Mindset Is Needed for This Role?

Working in the chip industry comes with its fair share of requirements.  Given the sensitivity and technicality involved, I have found out that the best strategy is bringing together different minds when working on a project. Teamwork has constantly helped me in my career. As for the right mindset, one needs to be focused and result-oriented when working on different projects. 在芯片行業工作有相當多的要求。考慮到所涉及的敏感性和技術性，我發現最好的策略是在開展項目時匯集不同的思想。團隊合作在我的職業生涯中不斷幫助我。至於正確的心態，在從事不同的項目時，需要專注並以結果為導向。

9.    What Do You Understand by a DPI Call?

DPI is the short form for Direct Programming Interface, a bridge between SystemVerilog and any foreign programming language such as Python. It enables direct inter-language function calls between the languages on each side of the interface. DPI 是 Direct Programming Interface 的縮寫形式，是 SystemVerilog 和任何外國編程語言（如 Python）之間的橋樑。它支持在界面每一側的語言之間進行直接的語言間函數調用。

Through the DPI layer, both imported and exported functions implemented in the C language can be expelled. DPI, therefore, supports both functions and tasks across the boundary. Only the Verilog data types can cross the boundary between System Verilog and a foreign language both ways. 通過DPI層，C語言實現的導入導出函數都可以被驅逐。因此，DPI 支持跨邊界的功能和任務。只有 Verilog 數據類型可以雙向跨越 System Verilog 和外語之間的邊界。

10. While Still on DPI, Could You Tell Us the Difference Between DPI Import and DPI export

A DPI imported function is implemented in the C language and is usually called in the SystemVerilog code. On the other hand, a DPI exported function is implemented in the SystemVerilog and exported to the C language, from where it is called. Both functions and tasks can be imported and exported. DPI 導入函數用 C 語言實現，通常在 SystemVerilog 代碼中調用。另一方面，DPI 導出函數在 SystemVerilog 中實現並導出到 C 語言，從那裡調用它。函數和任務都可以導入和導出。

11. What Do You Understand by System Tasks and Functions? Please Give Us Some Examples of System Tasks and Functions

There are several built-in system tasks and functions for different utilities supported by SystemVerilog language. These are generally called with a given prefix to the task/ function name. This language also allows one to add user-defined system tasks and functions. SystemVerilog 語言支持的不同實用程序有幾個內置的系統任務和功能。這些通常使用給定的任務/函數名稱前綴來調用。這種語言還允許添加用戶定義的系統任務和功能。

There are different examples of system tasks and functions which are grouped based on functionality. These are simulation control tasks, conversion functions, bit vector system functions, severity tasks, assertion control tasks, and sampled value system functions. 有不同的系統任務和功能示例，它們根據功能進行分組。這些是模擬控制任務、轉換函數、位向量系統函數、嚴重性任務、斷言控制任務和採樣值系統函數。

12. Could You Please Differentiate Parameter in System Verilog and Typedef?

A parameter in system Verilog is a constant value within the module structure. It can be used to define several attributes for the module and normally characterizes the behavior and the physical representation of the module. The parameter can be overridden at instantiation time. 系統 Verilog 中的參數是模塊結構中的常數值。它可用於定義模塊的多個屬性，通常表徵模塊的行為和物理表示。該參數可以在實例化時被覆蓋。

Parameters have to be overridden in the order in which they were defined if they exist in multiples. However, if the overriding value is not specified, one can use the default parameter declaration values. 如果參數以多個形式存在，則必須按照定義它們的順序覆蓋參數。但是，如果未指定覆蓋值，則可以使用默認參數聲明值。

On the other hand, Typedef lets users craft unique names for type definitions to be frequently used in their codes. They come in handy when building technical array definitions. 另一方面，Typedef 允許用戶為在他們的代碼中經常使用的類型定義創建唯一的名稱。在構建技術數組定義時，它們會派上用場。

13. Could You Explain the Difference Between These Different Data Types: Logic, Reg, and Wire?

Wire data is used in continuous assignments or ports list and is thus treated as a wire. It cannot hold any value but can be driven and read. It is used to connect different modules. 連線數據用於連續分配或端口列表，因此被視為連線。它不能保存任何值，但可以驅動和讀取。它用於連接不同的模塊。 Reg is a data storage element in the Verilog system. Even though it is not actual hardware, it can still store values. Reg 是 Verilog 系統中的數據存儲元素。即使它不是實際的硬件，它仍然可以存儲值。 Logic is an additional datatype in system Verilog that extends the rand. It can be easily driven by a single driver, such as a module. 邏輯是系統 Verilog 中擴展 rand 的附加數據類型。它可以很容易地由單個驅動程序驅動，例如一個模塊。

14. Mention the Need of Clocking Blocks

A clocking block has several users, which system Verilog officers appreciate. It is used to specify synchronization characteristics of a design and helps in testbench driving the signals at the right time. The clocking block also offers a clean way to drive and sample designs and race-free operation in specific applications. 一個時鐘塊有幾個用戶，System Verilog 提供激勵。它用於指定設計的同步特性，並有助於測試平台在正確的時間驅動信號。時鐘模塊還提供了一種干淨的方式來驅動和採樣設計以及特定應用中的無競爭操作。

15. What Is the Use of Packages in System Verilog?

The data, task, or function within a module are only specific to the module in Verilog declaration. These cannot be shared between two modules and can only be achieved via cross-module referencing or including the files. However, these are not proper solutions. 模塊中的數據、任務或函數僅特定於 Verilog 聲明中的模塊。這些不能在兩個模塊之間共享，只能通過跨模塊引用或包含文件來實現。然而，這些都不是適當的解決方案。

Packages, therefore, come in to solve this issue. It allows global data, task, or function declaration to be used across different modules. The package also contains content that can be accessed using scope resolution operator or import. They, therefore, play an essential role in system Verilog. 因此，包進來解決這個問題。它允許跨不同模塊使用全局數據、任務或函數聲明。該包還包含可以使用範圍調節運算符或導入訪問的內容。因此，它們在系統 Verilog 中發揮著重要作用。

16. Detail the Difference Between Rand and Randc

Rand is a random variable whose same value may be arrived at before returning all the possible values. It can be compared to throwing dice. Randc, on the other hand, refers to a random cyclic variable whose same value cannot be returned unless all the possible values have been returned. It can be compared to picking a card from a group of cards without making any replacements. Rand 是一個隨機變量，在返回所有可能的值之前，它的值可能相同。可以比作擲骰子。另一方面，randc 是指一個隨機循環變量，除非所有可能的值都已返回，否則無法返回相同的值。它可以類比為從一組卡片中挑選一張卡片而不進行任何替換。

17. Could You Please Explain Pass by Ref and Pass by Value?

Pass by value is the default method by which arguments are relayed into functions and tasks. Each subroutine usually stays with a copy of the argument. This plays one significant role. If the arguments are ever changed within the subroutine declaration, the changes do not at any point affect the caller. 按值傳遞是將參數傳遞給函數和任務的默認方法。每個子例程通常保留一個參數的副本。這起著重要的作用。如果在子例程聲明中更改了參數，則更改在任何時候都不會影響調用者。

On the other hand, functions and tasks directly access the set out variables passed as arguments in the pass by reference. It can be accurately termed as the passing pointer of the variable. 另一方面，函數和任務直接訪問在按引用傳遞中作為參數傳遞的設定變量。它可以準確地稱為變量的傳遞指針。

18. What Do You Understand by Program Block and Module? What are The Differences, If Any?

A program block is a new addition to system Verilog, which has its purposes. It separates the testbench from DUT, ensures that the testbench does not have any race condition with DUT, offers an entry point for testbench execution, and offers syntactic context for scheduling in the reactive regions. 程序塊是 Verilog 系統的新增功能，有其用途。它將測試平台與 DUT 分離，確保測試平台與 DUT 沒有任何競爭條件，為測試平台執行提供入口點，並為反應區域中的調度提供語法上下文。

There are several differences between the module and program blocks. Modules can always have blocks inside them, which is not possible for modules. Modules can also have UDP, which program blocks do not have. 模塊和程序塊之間有幾個不同之處。模塊內部總是可以有塊，這對於模塊是不可能的。模塊也可以有 UDP，而程序塊沒有。

Their execution regions also differ. Whereas program blocks are executed in the reactive region of the scheduling queue, module blocks are executed in the active region. Lastly, a program can call a task in modules, which a module cannot do. 它們的執行區域也不同。程序塊在調度隊列的反應區域中執行，模塊塊在活動區域中執行。最後，程序可以調用模塊中的任務，這是模塊無法做到的。

19. Why Do You Need an Alias in System Verilog?

A system Verilog has an alias statement that offers bidirectional and short circuit connection. Generally, the Verilog has only a one-way assign statement, which may also have delay and strength change for unidirectional assignment.  系統 Verilog 具有提供雙向和短路連接的別名語句。一般Verilog只有單向賦值語句，單向賦值也可能有延遲和強度變化。

20. Could You Please Tell Us the Difference Between Initial and Final Blocks?

The primary difference between these two types of blocks is that the first one is executed at the beginning of the simulation, whereas the final block at the end. The final block must also be executed promptly, whereas initial blocks have no execution restriction. They can delay and wait. 這兩種類型的塊之間的主要區別在於第一個在模擬開始時執行，而最後一個塊在結束時執行。最終塊也必須迅速執行，而初始塊沒有執行限制。他們可以延遲和等待。

The final blocks can also be used to display statistical information on the status of the execution. 最後的塊還可用於顯示有關執行狀態的統計信息。

21. How Do You Check Whether a Handle is Holding Objects or Not?

Checking whether a handle is holding objects or not ascertains whether the object t is initialized. All the uninitialized object handles in SystemVerilog have a null value and can be checked by comparing the object handle to null. 查句柄是否持有對象可以確定對象 t 是否已初始化。 SystemVerilog 中所有未初始化的對象句柄都有一個空值，可以通過將對象句柄與空值進行比較來檢查。

22. What Do You Understand by Bi-Directional Constraints?

Constraints are by default bi-directional. The constraint solver does not, therefore, follow the specified sequence of constraints. All the variables are therefore looked at simultaneously. This also applies to procedural-looking constraints such as if else and -> constraints. 約束默認是雙向的。因此，約束求解器不遵循指定的約束序列。因此，同時查看所有變量。這也適用於程序化約束，例如 if else 和 -> 約束。

23. Do You Know The Difference Between Always_comb and Always@(*)?

The first one (mention it in your speech) is executed once at a time, whereas the second one delays until a change occur on a signal. The statement in the always_comb cannot have any blocking timing, fork-join statement, or event control, whereas the latter does not have any of that restriction. 第一個（在你的演講中提到它）一次執行一次，而第二個延遲直到信號發生變化。 always_comb 中的語句不能有任何阻塞時間、fork-join 語句或事件控制，而後者沒有任何限制。

The former is change-sensitive, especially within a function, whereas the latter is only sensitive to changes to the function arguments. 前者對變化敏感，尤其是在函數內，而後者只對函數參數的變化敏感。

24. Please Tell Us What a Queue Is

A queue is a variable-size and ordered collection of uniform elements. It can be compared to a dimensional unpacked array which automatically grows and reduces in size. Queues are generally used to model a last-in, first-out buffer, and a last-in. 隊列是統一元素的可變大小和有序集合。它可以與自動增長和減小大小的維度解包數組進行比較。隊列通常用於對後進先出緩衝區和後進進行建模。

25. Mention Some of The Ways of Avoiding Race Conditioning Between Testbench and RTL

Avoiding race conditioning between testbench and RTL suing system Verilog can be done through program block, clocking block, and use of non-block assignments. 可以通過程序塊、時鐘塊和使用非塊分配來避免測試台和 RTL 起訴系統 Verilog 之間的競爭條件。

Conclusion

We have exhausted some of the most common system Verilog interview questions and answers. These should help you land your desired system Verilog role.