ABSTRACT
This is a long chapter, but for good reasons. Arithmetic operations are probably one of the more common types of instructions you will use, especially if the software being written involves manipulating large amounts of data, such as an incoming audio signal. Graphics algorithms, speech processing algorithms, digital controllers, and audio processing all involve a great deal of arithmetic work, so it’s important to understand the types of data that you have and how to perform the operation needed in the shortest amount of time and/or space. We begin with a discussion of flags, examine the basic arithmetic instructions for both the ARM7TDMI and the Cortex-M4, quickly examine some of the new DSP extensions in the Cortex-M4, and then wrap up with an overview of fractional arithmetic. Once you gain a good understanding of the concepts behind integer arithmetic, you should then be able to tackle floating-point arithmetic in Chapters 9, 10, and 11, and even go on to more advanced functions, such as trigonometric functions, exponentials, and square roots.
