Professional Assembly Language

Chapter 8. Basic Math Functions

Now that you have the different numeric data types under your belt, you can start using them in mathematical operations. This chapter dives into the basic integer math functions that are available in assembly language.

First the chapter describes how integer arithmetic is performed on the processor, and how you can utilize it in your assembly language programs. The instructions used for unsigned and signed addition, subtraction, multiplication, and division are shown, along with examples of how they are used in programs. Next described are the shift instructions, which help you increase the performance of your multiplication and division operations. After that, decimal arithmetic is explained, along with the instructions to implement it. The chapter finishes by describing the basic Boolean logic and bit testing instructions that are available on the IA-32 platform.

Integer Arithmetic

The basic building block for performing mathematical operations in assembly language programs is integer arithmetic. You should have a full understanding of how the processor performs mathematical operations on integers before you try diving into the more complex floating-point math functions.

This section describes how integer math is performed on the processor, and how you can use integer math in your assembly language programs. This includes integer addition, subtraction, multiplication, and division.

Addition

While it would seem that adding two integers together should ...