Programming from the Ground Up
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Programming from the Ground Up Jonathan Bartlett Edited by Dominick Bruno, Jr. Programming from the Ground Up by Jonathan Bartlett Edited by Dominick Bruno, Jr. Copyright © 2003 by Jonathan Bartlett Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in Appendix H. In addition, you are granted full rights to use the code examples for any purpose without even having to credit the authors. All trademarks are property of their respective owners. This book can be purchased at http://www.bartlettpublishing.com/ This book is not a reference book, it is an introductory book. It is therefore not suitable by itself to learn how to professionally program in x86 assembly language, as some details have been left out to make the learning process smoother. The point of the book is to help the student understand how assembly language and computer programming works, not to be a reference to the subject. Reference information about a particular processor can be obtained by contacting the company which makes it. To receive a copy of this book in electronic form, please visit the website http://savannah.nongnu.org/projects/pgubook/ This site contains the instructions for downloading a transparent copy of this book as defined by the GNU Free Documentation License. Table of Contents 1. Introduction........................................................................................................1 Welcome to Programming ...............................................................................1 Your Tools........................................................................................................3 2. Computer Architecture .....................................................................................7 Structure of Computer Memory.......................................................................7 The CPU...........................................................................................................9 Some Terms ...................................................................................................11 Interpreting Memory......................................................................................13 Data Accessing Methods................................................................................14 Review ...........................................................................................................16 3. Your First Programs ........................................................................................19 Entering in the Program.................................................................................19 Outline of an Assembly Language Program..................................................22 Planning the Program.....................................................................................28 Finding a Maximum Value.............................................................................31 Addressing Modes .........................................................................................41 Review ...........................................................................................................45 4. All About Functions.........................................................................................49 Dealing with Complexity...............................................................................49 How Functions Work .....................................................................................50 Assembly-Language Functions using the C Calling Convention ..................52 A Function Example ......................................................................................59 Recursive Functions.......................................................................................64 Review ...........................................................................................................71 5. Dealing with Files.............................................................................................75 The UNIX File Concept.................................................................................75 Buffers and .bss ...........................................................................................76 Standard and Special Files.............................................................................78 Using Files in a Program................................................................................79 iii Review ...........................................................................................................93 6. Reading and Writing Simple Records ...........................................................95 Writing Records...........................................................................................100 Reading Records ..........................................................................................104 Modifying the Records ................................................................................111 Review .........................................................................................................114 7. Developing Robust Programs........................................................................117 Where Does the Time Go?...........................................................................117 Some Tips for Developing Robust Programs...............................................118 Handling Errors Effectively .........................................................................121 Making Our Program More Robust .............................................................123 Review .........................................................................................................126 8. Sharing Functions with Code Libraries.......................................................129 Using a Shared Library ................................................................................130 How Shared Libraries Work ........................................................................133 Finding Information about Libraries............................................................134 Useful Functions ..........................................................................................140 Building a Shared Library............................................................................141 Review .........................................................................................................143 9. Intermediate Memory Topics........................................................................147 How a Computer Views Memory ................................................................147 The Memory Layout of a Linux Program....................................................149 Every Memory Address is a Lie ..................................................................151 Getting More Memory .................................................................................155 A Simple Memory Manager ........................................................................157 Using our Allocator......................................................................................174 More Information.........................................................................................177 Review .........................................................................................................178 iv 10. Counting Like a Computer .........................................................................181 Counting.......................................................................................................181 Truth, Falsehood, and Binary Numbers .......................................................186 The Program Status Register .......................................................................195 Other Numbering Systems...........................................................................196 Octal and Hexadecimal Numbers ................................................................199 Order of Bytes in a Word .............................................................................201 Converting Numbers for Display.................................................................204 Review .........................................................................................................210 11. High-Level Languages .................................................................................213 Compiled and Interpreted Languages ..........................................................213 Your First C Program...................................................................................215 Perl ...............................................................................................................218 Python ..........................................................................................................219 Review .........................................................................................................220 12. Optimization.................................................................................................223 When to Optimize........................................................................................223 Where to Optimize.......................................................................................224 Local Optimizations.....................................................................................225