Book Image

Mastering Assembly Programming

By : Alexey Lyashko
3 (1)
Book Image

Mastering Assembly Programming

3 (1)
By: Alexey Lyashko

Overview of this book

The Assembly language is the lowest level human readable programming language on any platform. Knowing the way things are on the Assembly level will help developers design their code in a much more elegant and efficient way. It may be produced by compiling source code from a high-level programming language (such as C/C++) but can also be written from scratch. Assembly code can be converted to machine code using an assembler. The first section of the book starts with setting up the development environment on Windows and Linux, mentioning most common toolchains. The reader is led through the basic structure of CPU and memory, and is presented the most important Assembly instructions through examples for both Windows and Linux, 32 and 64 bits. Then the reader would understand how high level languages are translated into Assembly and then compiled into object code. Finally we will cover patching existing code, either legacy code without sources or a running code in same or remote process.
Table of Contents (12 chapters)
Free Chapter
1
Intel Architecture

Data types and their definitions

Before we start working with Assembly instructions, we have to know how to define data, or, to be more precise, how to tell the assembler which type of data we are using.

The Flat Assembler supports six built-in types of data and allows us to either define or declare variables. The difference between a definition and a declaration in this case is that when we define a variable we also assign a certain value to it, but when we declare, we simply reserve space for a certain type of data:

Variable definition format: [label] definition_directive value(s)

  • label: This is optional, but addressing an unnamed variable is harder

Variable declaration format: [label] declaration_directive count

  • label: This is optional, but addressing an unnamed variable is harder
  • count: This tells the assembler how many entries of the type specified in declaration_directive...