1. Chapter 17 Programming Tools The Architecture of Computer Hardware and Systems Software: An Information Technology Approach 3rd Edition, Irv Englander John Wiley and Sons  2003 Wilson Wong, Bentley College Linda Senne, Bentley College

2. Chapter 17 Programming Tools 17-2 Programming Tools Overview  Editors  Assemblers  Debuggers  Compilers  Linkers  Loaders  Interpreters Integrated Development Environments (IDEs) combine several of the above programming tools

3. Chapter 17 Programming Tools 17-3 The Program Translation Process  Terms, terms, and more terms! Source Object Executable Translator Linker Loader

4. Chapter 17 Programming Tools 17-4 Visual Basic IDE

5. Chapter 17 Programming Tools 17-5 Program Text Editors  Word processors format the appearance of the text  Text editors  Format the spacing between words for legibility  Ideal for structured languages  Text is the same font size  Examples  DOS – Edit  Windows – Notepad, Wordpad  Unix / Linux – ed, vi, emacs  IDEs  MS Visual C++, Symantec Visual Cafe

6. Chapter 17 Programming Tools 17-6 Programming Language Categories  Machine Language  Binary coded instructions  Assembly Language  Symbolic coded instructions  Procedural Languages  procedural statements or arithmetic notation  Four-generation Languages  Natural language and nonprocedural statements  Object-oriented Languages  Combination of objects and procedures

7. Chapter 17 Programming Tools 17-7 Assembly Language  When to use  When speed or size of program is critical  Hybrid approach  Hardware Drivers  Can use specialized instructions  Disadvantages  Inherently machine specific  Architectures may become obsolete  Lack of programming structure

8. Chapter 17 Programming Tools 17-8 Assemblers  Binary code = machine code  Hex code  Assembly Language  Mnemonic names  op codes  Labels  memory addresses  Comments  Symbol table  Operations table  Memory Relocation  Cross Assembler

9. Chapter 17 Programming Tools 17-9 What Does This Program Do?

10. Chapter 17 Programming Tools 17-10 LMC Program in Java  Use instructions in a more understandable language static int max (int x[]) { for (i=1; i<=3; i++) x[i] = input.getint(); max_int = x[1]; for (i=2; i<=3; i++) if (x[I] > max_int) max_int = x[I]; System.output.println(max_int); }

11. Chapter 17 Programming Tools 17-11 Procedural Languages  COBOL  Wordy but easier to maintain  FORTRAN  Scientists and engineers  BASIC  Pascal  Highly structured teaching language  C  high-level commands and low-level access to hardware

12. Chapter 17 Programming Tools 17-12 Object-Oriented Languages  SmallTalk  C++  Java  Based on C++  Platform independent

13. Chapter 17 Programming Tools 17-13 Compilers  Translates high-level language into low- level instructions  High-level language: Source code  Machine-level: Object code  Changes, including bug fixes, require recompiling

14. Chapter 17 Programming Tools 17-14 Language Components  Lexicon  All legal words in the language  Meaning and type  Syntax  grammar rules  Semantics  meaning of command

15. Chapter 17 Programming Tools 17-15 Computer Language Descriptions  Narrative  Syntax (Railroad) Diagrams  BNF  Backus-Naur Form  Context-Free Grammar

16. Chapter 17 Programming Tools 17-16 Railroad Diagram Examples

17. Chapter 17 Programming Tools 17-17 Typical BNF Rules for Java

18. Chapter 17 Programming Tools 17-18 Parsed English Sentence

19. Chapter 17 Programming Tools 17-19 The Compilation Process Checks for errors Generates CPU instructions or library calls Updates internal tables

20. Chapter 17 Programming Tools 17-20 Process of Parsing  Lexical analysis  Also known as scanning  Divides the string of input characters into single elements, tokens, based on strict computer punctuation  Syntactic analysis  Checks for errors in grammar rules  Semantic parsing  Determines the meaning of the string

21. Chapter 17 Programming Tools 17-21 Source Code Instructions  Data declarations:  Data type such as floating point, integer  Data operations  Instructions that update or compute data value (lots of moving around!)  Control Structures  Branches, Goto (yetch!), If-then-else, loops such as While-do and Repeat-until  Function, procedure, or subroutine calls  Receives control via a call instruction, receives and possibly modifies parameters, and returns control to the instruction after the call

22. Chapter 17 Programming Tools 17-22 Recursive Descent Parsing

23. Chapter 17 Programming Tools 17-23 Optimization  Compiler analyzes code in order to  Reduce amount of code  Eliminate repeated operations  Reorganize parts of of the program to execute faster and more efficiently  Use computer resources more effectively  Example  Move a calculation repeated within the body of a loop that does not use any value modified by the loop  Different compilers can produce different results!

24. Chapter 17 Programming Tools 17-24 Object file or object module Object file C library Executable file Linker Linking

25. Chapter 17 Programming Tools 17-25 Linkers  Searches program libraries to find library routines used by the program  Library: collection of pre-written functions and subroutines made available to perform commonly required activities  Determines the memory locations that code from each module will occupy and relocates instructions by adjusting absolute references  Resolves references among files

26. Chapter 17 Programming Tools 17-26 Why Link?  Construct single executable program from multiple object code files compiled at different times  Program can be subdivided into components and parceled out to different developers  Example  Main program and multiple subroutines written and compiled by different programmers at different times

27. Chapter 17 Programming Tools 17-27 Loader  Loads binary files that have been linked into main memory  Program is ready for execution

28. Chapter 17 Programming Tools 17-28 Interpreters  Translates source code instructions into machine language and executes it one statement at a time  Disadvantages  Longer to execute, particularly bad for loops  Uses more memory  Advantage  Faster testing and code modification  Examples of interpreted languages  Java, BASIC, LISP

29. Chapter 17 Programming Tools 17-29 Interpreter vs. Compiler Resources during executionInterpreterCompiler Contents in memory Interpreter/compilerYesNo Source codePartialNo Executable codeYes CPU cycles Translation operationsYesNo Library linkingYesNo Application programYes

30. Chapter 17 Programming Tools 17-30 Debuggers  Assembly language debuggers  Source code debuggers  Step through programs  Check variable values

31. Chapter 17 Programming Tools 17-31 Copyright 2003 John Wiley & Sons All rights reserved. Reproduction or translation of this work beyond that permitted in Section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the permissions Department, John Wiley & Songs, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publisher assumes no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information contained herein.”