The Verilog(r) Hardware Description Language

ISBN-13: 9781461367840 / Angielski / Miękka / 2012 / 223 str.

Donald E. Thomas; Philip R. Moorby

Opis

The Verilog language is a hardware description language which provides a means of specifying a digital system at a wide range of levels of abstraction. The language supports the early conceptual stages of design with its behavioral level of abstraction, and the later implementation stages with its structural level of abstraction. The language provides hierarchical constructs, allowing the designer to control the complexity of a description. Verilog was originally designed in the winter of 1983/84 as a proprietary verification/simulation product. Since then, several other proprietary analysis tools have been developed around the language, including a fault simulator and a timing analyzer; the language being instrumental in providing consistency across these tools. Now, the language is openly available for any tool to read and write. This book introduces the language. It is sometimes difficult to separate the language from the simulator tool because the dynamic aspects of the language are defined by the way the simulator works. Where possible, we have stayed away from simulator-specific details and concentrated on design specification, but have included enough information to be able to have working executable models. The book takes a tutorial approach to presenting the language.

Spis treści

1. Verilog — A Tutorial Introduction.- 1.1 Describing Digital Systems.- 1.2 Getting Started.- 1.2.1 A Structural Description.- 1.2.2 Simulating the NAND Latch.- 1.3 Module Hierarchy.- 1.3.1 The Counter.- 1.3.2 Components of the Counter.- 1.3.3 A Clock for the System.- 1.3.4 Tying the Whole Circuit Together.- 1.4 Behavioral Modeling.- 1.4.1 A Behavioral Model of the m16 Counter.- 1.4.2 Mixing Structure and Behavior.- 1.4.3 Assignment Statements.- 1.4.4 Mixing Behavioral and Structural Descriptions.- 1.5 Summary.- 1.6 Exercises.- 2. Behavioral Modeling Constructs.- 2.1 Process Model.- 2.2 If-Then-Else.- 2.2.1 Where Does The ELSE Belong?.- 2.2.2 The Conditional Operator.- 2.3 Loops.- 2.3.1 Four Basic Loop Statements.- 2.3.2 Exiting Loops on Exceptional Conditions.- 2.4 Multi-way branching.- 2.4.1 If-Else-If.- 2.4.2 Case.- 2.4.3 Comparison of Case and If-Else-If.- 2.4.4 CaseZ and CaseX.- 2.5 Functions and Tasks.- 2.5.1 Tasks.- 2.5.2 Functions.- 2.5.3 A Structural View.- 2.6 Summary.- 2.7 Exercises.- 3. Concurrent Process Statements.- 3.1 Concurrent Processes.- 3.2 Events.- 3.2.1 Event Control Statement.- 3.2.2 Named Events.- 3.2.3 An Example of Hierarchical Names.- 3.3 The Wait Statement.- 3.3.1 A Complete Producer-Consumer Handshake.- 3.3.2 Comparison of the Wait and While Statements.- 3.3.3 Comparison of Wait and Event Control Statements.- 3.4 Disabling Named Blocks.- 3.5 Quasi-continuous assignment.- 3.6 Sequential and Parallel Blocks.- 3.7 Exercises.- 4. Logic Level Modeling.- 4.1 Introduction.- 4.2 Logic Gates and Nets.- 4.2.1 Modeling Using Primitive Logic Gates.- 4.2.2 Four-Level Logic Values.- 4.2.3 Nets.- 4.2.4 Module Port Specifications.- 4.3 Continuous Assignment.- 4.3.1 Behavioral Modeling of Combinational Circuits.- 4.3.2 Net and Continuous Assign Declarations.- 4.4 Parameterized Definitions.- 4.5 Logic Delay Modeling.- 4.5.1 A Gate Level Modeling Example.- 4.5.2 Gate and Net Delays.- 4.5.3 Minimum, Typical, and Maximum Delays.- 4.6 Delay Paths Across a Module.- 4.7 Summary.- 4.8 Exercises.- 5. Defining Gate Level Primitives.- 5.1 Combinational Primitives.- 5.1.1 Basic Features of User-Defined Primitives.- 5.1.2 Describing Combinational Logic Circuits.- 5.2 Level- and Edge-Sensitive Sequential Primitives.- 5.2.1 Level-Sensitive Primitives.- 5.2.2 Edge-Sensitive Primitives.- 5.3 Shorthand Notation.- 5.4 Mixed Level- and Edge-Sensitive Primitives.- 5.5 Summary.- 5.6 Exercises.- 6. Switch Level Modeling.- 6.1 A Dynamic MOS Shift Register Example.- 6.2 Switch Level Modeling.- 6.2.1 Strength Modeling.- 6.2.2 Strength Definitions.- 6.2.3 An Example Using Strengths.- 6.2.4 Resistive MOS Gates.- 6.3 Ambiguous Strengths.- 6.3.1 Illustrations of Ambiguous Strengths.- 6.3.2 The Underlying Calculations.- 6.4 Summary.- 6.5 Exercises.- 7. Two Large Examples.- 7.1 The miniSim Example.- 7.1.1 Overview.- 7.1.2 The miniSim Source.- 7.1.3 Simulation Results.- 7.2 The 8251A Example.- 7.2.1 Overview.- 7.2.2 The 8251A Source.- 7.3 Exercises.- Appendix A. Lexical Conventions.- A.1 White Space and Comments.- A.2 Operators.- A.3 Numbers.- A.4 Strings.- A.5 Identifiers, System Names, and Keywords.- Appendix B. Verilog Operators.- B.1 Table of Operators.- B.2 Operator Precedence.- B.3 Operator Truth Tables.- B.3.1 Bitwise AND.- B.3.2 Bitwise OR.- B.3.3 Bitwise XOR.- B.3.4 Bitwise XNOR.- B.4 Expression Bit Lengths.- Appendix C. Verilog Gate Types.- C.1 Logic Gates.- C.2 BUF and NOT Gates.- C.3 BUFIF and NOTIF Gates.- C.4 MOS Gates.- C.5 Bidirectional Gates.- C.6 CMOS Gates.- C.7 Pullup and Pulldown Gates.- Appendix D. Registers, Memories, Integers, and Time.- D.1 Registers.- D.2 Memories.- D.3 Integers and Times.- Appendix E. System Tasks and Functions.- E.1 Display and Write Tasks.- E.2 Continuous Monitoring.- E.3 Strobed Monitoring.- E.4 File Output.- E.5 Simulation Time.- E.6 Stop and Finish.- E.7 Random.- Appendix F. Formal Syntax Definition.- F.1 Source Text.- F.2 Declarations.- F.3 Primitive Instances.- F.4 Module Instantiations.- F.5 Behavioral Statements.- F.6 Specify Section.- F.7 Expressions.- F.8 General.