Book Image

ARM® Cortex® M4 Cookbook

By : Mark Fisher, Dr. Mark Fisher
Book Image

ARM® Cortex® M4 Cookbook

By: Mark Fisher, Dr. Mark Fisher

Overview of this book

Embedded microcontrollers are at the core of many everyday electronic devices. Electronic automotive systems rely on these devices for engine management, anti-lock brakes, in car entertainment, automatic transmission, active suspension, satellite navigation, etc. The so-called internet of things drives the market for such technology, so much so that embedded cores now represent 90% of all processor’s sold. The ARM Cortex-M4 is one of the most powerful microcontrollers on the market and includes a floating point unit (FPU) which enables it to address applications. The ARM Cortex-M4 Microcontroller Cookbook provides a practical introduction to programming an embedded microcontroller architecture. This book attempts to address this through a series of recipes that develop embedded applications targeting the ARM-Cortex M4 device family. The recipes in this book have all been tested using the Keil MCBSTM32F400 board. This board includes a small graphic LCD touchscreen (320x240 pixels) that can be used to create a variety of 2D gaming applications. These motivate a younger audience and are used throughout the book to illustrate particular hardware peripherals and software concepts. C language is used predominantly throughout but one chapter is devoted to recipes involving assembly language. Programs are mostly written using ARM’s free microcontroller development kit (MDK) but for those looking for open source development environments the book also shows how to configure the ARM-GNU toolchain. Some of the recipes described in the book are the basis for laboratories and assignments undertaken by undergraduates.
Table of Contents (16 chapters)
ARM Cortex M4 Cookbook
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Implementing a jump table


Under certain circumstances, a jump table provides a very efficient way of implementing a C language switch statement block. We can define a jump table as a list of unconditional branch instructions—each referencing a different procedure or subroutine. We branch to one of the subroutines by loading the program counter with the address of the unconditional branch that is stored in the jump table. The effective addresses of items in the jump table are formed using a base + offset addressing mode. Base + offset addressing is commonly used to access data items stored in arrays, and a jump table is effectively just an array of address items.

Getting ready

To illustrate a jump table, we'll develop a recipe called asmJumpTable_c4v0. Assume that we have a function named jumpT () that accepts a val integer input argument. The function calls either proc1 (), proc2 (), or proc3 (), depending on the value of the input argument:

void jumpT ( int val ) {

  switch (val) {
    case...