This book is supposed to teach you methods of numerical computing that are practical, efficient, and (insofar as possible) elegant. We presume throughout this book that you, the reader, have particular tasks that you want to get done. We view our job as educating you on how to proceed. Occasionally we may try to reroute you briefly onto a particularly beautiful side road; but by and large, we will guide you along main highways that lead to practical destinations.
The book begins by briefly noting theARMprocessor design philosophy and discussing how
and why it differs from the traditional RISC philosophy. The first chapter also introduces a
simple embedded system based on the ARM processor.
Chapter 2 digs more deeply into the hardware, focusing on the ARM processor core and
presenting an overview of the ARM cores currently in the marketplace.
The ARM and Thumb instruction sets are the focus of Chapters 3 and 4, respectively,
and form the fundamental basis for the rest of the book. Explanations of key instructions
include complete examples, so these chapters also serve as a tutorial on the instruction sets.
Chapters 5 and 6 demonstrate how to write efficient code with scores of example that we
have developed while working with ARM customers. Chapter 5 teaches proven techniquesand rules for writing C code that will compile efficiently on the ARM architecture, and it
helps determine which code should be optimized. Chapter 6 details best practices for writing
and optimizing ARM assembly code—critical for improving performance by reducing
system power consumption and clock speed.
Because primitives are basic operations used in a wide range of algorithms, it’s worthwhile
to learn how they can be optimized. Chapter 7 discusses how to optimize primitives
for specific ARM processors. It presents optimized reference implementations of common
primitives as well as of more complicated mathematical operations for those who
wish to take a quick reference approach. We have also included the theory behind each
implementation for those who wish to dig deeper.
Audio and video embedded systems applications are increasingly in demand. They
require digital signal processing (DSP) capability that until recently would have been provided
by a separate DSP processor. Now, however, the ARM architecture offers higher
memory bandwidths and faster multiply accumulate operations, permitting a single ARM
core design to support these applications. Chapter 8 examines how to maximize the performance
of the ARM for digital processing applications and how to implement DSP
algorithms.
At the heart of an embedded system lie the exception handlers. Efficient handlers
can dramatically improve system performance. Chapter 9 covers the theory and practice
of handling exceptions and interrupts on the ARM processor through a set of detailed
examples.
Firmware, an important part of any embedded system, is described in Chapter 10 by
means of a simple firmware package we designed, called Sandstone. The chapter also reviews
popular industry firmware packages that are available for the ARM.
Chapter 11 demonstrates the implementation of embedded operating systems through
an example operating system we designed, called Simple Little Operating System.
Chapters 12, 13, and 14 focus on memory issues. Chapter 12 examines the various
cache technologies that surround the ARM cores, demonstrating routines for controlling
the cache on specific cache-enabled ARM processors. Chapter 13 discusses the memory
protection unit, and Chapter 14 discusses the memory management unit.
Finally, in Chapter 15, we consider the future of the ARM architecture, highlighting
new directions in the instruction set and new technologies that ARM is implementing in
the next few years.
The appendices provide detailed references on the instruction sets, cycle timing, and
specific ARM products.
