Non-synthesizable constructs

Definition

Non-synthesizable constructs are elements within hardware description languages, like Verilog, that cannot be translated into actual physical hardware. These constructs are often used for modeling and simulation purposes rather than for synthesis, meaning they help in testing and verifying designs without being part of the final implemented circuit.

5 Must Know Facts For Your Next Test

1. Non-synthesizable constructs include features like initial blocks, delays, and certain types of procedural assignments that are useful for simulation but not for real hardware.
2. Using non-synthesizable constructs can help engineers quickly prototype and validate complex designs before committing to hardware implementation.
3. Common examples of non-synthesizable constructs in Verilog include 'always' blocks with delay statements or using the 'fork' keyword for concurrent execution.
4. When writing code in Verilog, it’s important to distinguish between synthesizable and non-synthesizable constructs to ensure the intended functionality translates correctly into hardware.
5. Non-synthesizable constructs can lead to confusion if designers are not careful, as they may think their code will synthesize when it won't, potentially resulting in costly design errors.

Review Questions

• How do non-synthesizable constructs differ from synthesizable ones in terms of usage in design verification?
  • Non-synthesizable constructs are primarily used for simulation and modeling purposes, allowing designers to test and verify their hardware designs before synthesis. In contrast, synthesizable constructs are those that can be directly translated into physical hardware. This distinction is crucial for engineers who want to ensure their designs work correctly in a simulated environment before implementing them on an actual chip.
• What are some common non-synthesizable constructs in Verilog, and why are they important for simulation?
  • Common non-synthesizable constructs in Verilog include initial blocks, delay statements, and procedural assignments that do not map directly to physical hardware components. These constructs are important for simulation because they allow designers to model behaviors such as timing, initialization sequences, or complex control flows that are essential for testing but cannot be realized in actual hardware. By using these constructs effectively, designers can identify issues early in the development process.
• Evaluate the implications of using non-synthesizable constructs in a design project and how it affects the verification process.
  • Using non-synthesizable constructs can significantly enhance the verification process by allowing engineers to create detailed simulations that capture intricate behaviors of the design. However, if these constructs are mistakenly believed to be synthesizable, it can lead to miscommunication within teams and costly errors during implementation. A clear understanding of when and where to use these constructs is essential for a successful design project, ensuring that the final hardware behaves as intended while avoiding pitfalls associated with non-functional code.

Related terms

Simulation: The process of mimicking the operation of a design using a model to predict its behavior without physically implementing it.

Synthesis: The process of converting a high-level hardware description language into a low-level representation suitable for physical implementation on hardware.

Testbench: A special type of code written to test and validate the functionality of a design by applying inputs and checking outputs in a simulated environment.