Robert Dunne - Assembly Language Coding in Color: ARM and NEON

Assembly Language Coding in Color: ARM and NEON

Copyright 2017 by Robert Dunne.

All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means without the prior written permission of the copyright owner and publisher. Published in the United States of America by Gaul Communications, Downers Grove, Illinois.

Cover Design: Daniel van Loon

ISBN 978-0-970112446 (paperback)

ISBN 978-0-970112439 (digital)

This book refers to and uses the GNU software and Linux kernel. See the GNU General Public License for details which is available from the Free Software Foundation, Inc., Boston, Massachusetts.

Assembly Language Coding in Color: ARM and NEON is an independent publication and has not been authorized, sponsored, or endorsed by any of the hardware or software rights holders described herein.

The publisher makes no warranty, express or implied, with respect to the material contained herein. The program listings, examples, and other information presented in this book are distributed on an as is basis, without warranty. Although every precaution has been taken in the preparation of this book, neither the author nor Gaul Communications shall have any liability regarding its use.

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ARM and NEON

Robert Dunne

A ssembly language is the computer programming language closest to a CPUs (Central Processing Unit) machine language. Learning to program in assembly language is an excellent hands-on introduction to computer architecture. However, assembly language has a bad reputation of being difficult to learn. After having taught college courses for over ten years, presented at international conferences for over twenty years, and even taught childrens gifted education courses, Ive learned that people have many different learning styles and objectives. This book is shorter and is more colorful than than typical textbooks used in a course on assembly language or computer architecture.

Is a book in color worth twice the print production costs of one in black and white? It is for those students struggling to get a working knowledge of a subject where they need to connect concepts to implementation. Learning computer architecture through hands-on assembly language programming experience helps develop well-rounded programmers and computer engineers.

• This tutorial introduces the novice to the basics of the ARM and NEON architectures.
• Although the Raspberry Pi and BeagleBone Black computers are ideal platforms for this book, most other Linux-based ARM systems are also compatible.
• Programmers learn by example and develop their skills by examining and modifying working programs. The sample programs in this book, ranging from five to over one hundred lines of code, are available for download through GitHub.
• Many assembly language books present CPU instructions in catalog form along with snippets of coding examples. In this book, CPU instructions are introduced as needed to achieve programming goals as the projects in each chapter progress to the next.
• Over fifty color illustrations are included to explain programming techniques as well as ARM and NEON instructions.
• Programming examples and flow diagrams are color coded to help connect concepts to implementation.
• Topics like binary and hexadecimal are introduced through programming examples as well as appearing in appendices.
• The examples in this book have been classroom tested with students having very little, if any, previous programming experience. The information is complete, allowing it to be used as an independent study.

The goal of this book is to assist students and computer enthusiasts to get on a solid path to understanding computer architecture. It is for those who may have struggled trying to learn assembly language using books that are basically black and white catalogs of computer hardware instructions. The intended audience is the following:

• Anyone wanting to learn assembly language, especially individuals interested in the Raspberry Pi, the BeagleBone Black, the ARM CPU, and NEON coprocessor architectures in particular.
• Someone who already has assembly language experience, but now wants to become familiar with the ARM CPU and NEON vector coprocessor.
• Students looking for a different approach to become comfortable with CPU architectural concepts and assembly language programming.

Expected prerequisites for someone reading this book to learn assembly language:

• Access to an ARM-based Linux system: Students should be able to get their computers into Linux command line mode. I have included an appendix using the Raspberry Pi as an example that should be adequate for many people needing some assistance.
• No programming experience necessary: Some of my electronics students have limited experience with Basic, C++, Python, or Java, but most have no programming experience.

Preliminary versions of this book have been field tested in the classroom by my electronics students. I have specifically targeted this book at those who wanted a different approach to learn computer architecture and assembly language, so it does not contain the following:

• All ARM and NEON instructions: The focus of this book is to get students programming and understanding the architecture as quickly as possible using the most common instructions. Individuals interested in more depth and covering subjects like floating point, software development, and the use of the debugger should consider my other book: Assembly Language Using the Raspberry Pi: A Hardware Software Bridge.
• Examples with assembly language with C: Although almost all of the embedded systems I have developed for production in the real world are a combination of assembly language with a higher level language like C, I decided to only cover that subject briefly in an appendix.
• Electronics interfacing examples: As you might expect in electronics classes, I always have lab exercises that either drive motors or read very sensitive, even micro-volt data. Again, I felt I couldnt properly cover that material in a professional way without almost doubling the size of this book.
• Linux applications development: I use only enough Linux service calls to demonstrate the programming techniques and examples. File I/O, as well as task and thread management, are not included.
• All program code in multiple colors: Color is used to highlight the particular set of instructions and programming techniques being presented at the time. Besides, a full-color 100-line program just looks like too much of a good thing,

The objective is to use hands-on programming examples to reinforce computer architecture concepts.

• The first chapter introduces the concepts and structure of CPU machine code through examples modeled as a calculator.
• A program named model is begun in Chapter 2 to demonstrate the work flow of using an editor, assembler, and linker to build and then test an assembly language program. Although it starts as a 5-line program, it will be modified in subsequent chapters until it becomes a 188-line program in Chapter 7.
• Chapter 3 enhances the model program with a read/write user interface and includes programming techniques such as nested loops.