SKILL Language User Guide

1 SKILL Language User GuideProduct Version 2007 1990-2007 Cadence Design Systems, Inc. All rights in the United States of Design Systems, Inc., 555 River Oaks Parkway, San Jose, CA 95134, USAT rademarks:Trademarks and service marks of Cadence Design Systems, Inc. (Cadence) contained inthis document are attributed to Cadence with the appropriate symbol. For queries regarding Cadence strademarks, contact the corporate legal department at the address shown above or call other trademarks are the property of their respective Print Permission:This publication is protected by copyright and any unauthorized use of thispublication may violate copyright, trademark, and other laws.

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4 Cadence does not warrant that use of such information will not infringe any third partyrights, nor does Cadence assume any liability for damages or costs of any kind that may result from use ofsuch Rights:Use, duplication, or disclosure by the Government is subject to restrictions as set forthin and et seq. or its Language User GuideJanuary 20073 Product Version .. 19 About the SKILL Language .. 20 Quick Look at All the Chapters .. 21 What s New .. 23 SKILL Development Helpful Hints .. 23 SKILL API Documentation .. 24 Document Conventions .. 24 Syntax Conventions.

5 24 Data Types .. 251 Getting Started.. 27 SKILL s Relationship to Lisp .. 28 Programming Notation .. 28 Data Manipulation .. 28 Characters .. 29 Cadence SKILL Language at a Glance .. 29 Terms and Definitions .. 30 Invoking a SKILL Function .. 31 Return Value of a Function .. 32 Simplest SKILL Data .. 32 Calling a Function .. 32 Operators Are SKILL Functions .. 33 Using Variables .. 33 Alternative Ways to Invoke a Function .. 34 Solving Some Common Problems .. 34 SKILL Lists .. 35 Building Lists .. 36 Accessing Lists.

6 38 Modifying Lists .. 39 File Input/Output ..40 ContentsSKILL Language User GuideJanuary 20074 Product Version Data .. 41 Writing Data to a File .. 42 Reading Data from a File .. 43 Flow of Control .. 45 Relational Operators .. 45 Logical Operators .. 46 The if Function .. 47 The when and unless Functions .. 48 The case Function .. 48 The for Function .. 49 The foreach Function .. 50 Developing a SKILL Function .. 51 Grouping SKILL Statements .. 51 Declaring a SKILL Function .. 52 Defining Function Parameters .. 52 Selecting Prefixes for Your Functions.

7 52 Maintaining SKILL Source Code .. 53 Loading Your SKILL Source Code .. 53 Redefining a SKILL Function .. 542 Language Characteristics .. 57 Naming Conventions .. 58 Names of Functions .. 58 Cadence-Private Functions .. 59 Names of Variables .. 59 Function Calls ..61 SKILL Syntax ..61 Special Characters .. 61 Comments .. 63 White Space .. 63 White Space Characters .. 64 Parentheses .. 64 Super Right Bracket .. 65 Backquote, Comma, and Comma-At .. 65 SKILL Language User GuideJanuary 20075 Product Version Continuation.

8 66 Length of Input Lists .. 66 Data Characteristics .. 66 Data Types .. 67 Numbers .. 68 Strings .. 70 Atoms .. 71 Escape Sequences .. 71 Symbols .. 72 Characters .. 723 Creating Functions in SKILL .. 75 Terms and Definitions .. 76 Kinds of Functions .. 77 Syntax Functions for Defining Functions .. 77procedure .. 77lambda .. 78nprocedure .. 78defmacro .. 78mprocedures .. 79 Summary of Syntax Functions .. 79 Defining Parameters .. 80@rest Option .. 80@optional Option .. 81@key Option .. 81 Combining Arguments.

9 82 Type Checking .. 82 Local Variables .. 83 Defining Local Variables Using the let Function .. 83 Defining Local Variables Using the prog Function .. 84 Initializing Local Variables to Non-nil Values .. 84 Global Variables .. 84 Testing Global Variables .. 85 Avoiding Name Clashes .. 85 SKILL Language User GuideJanuary 20076 Product Version Scheme .. 86 Reducing the Number of Global Variables .. 86 Redefining Existing Functions .. 86 Physical Limits for Functions .. 874 Data Structures .. 89 Access Operators .. 90 Symbols .. 90 Creating Symbols.

10 91 The Print Name of a Symbol .. 91 The Value of a Symbol .. 92 The Function Binding of a Symbol .. 93 The Property List of a Symbol .. 93 Important Symbol Property List Considerations .. 95 Disembodied Property Lists .. 95 Important Considerations .. 97 Additional Property List Functions .. 97 Strings .. 99 Concatenating Strings .. 99 Comparing Strings .. 100 Getting Character Information in Strings .. 101 Indexing with Character Pointers .. 101 Creating Substrings .. 102 Converting Case .. 103 Pattern Matching of Regular Expressions.