x86 assembly

This course is about one architecture, x86-64, and about writing programs for it.

If you have never written assembly before, read Assembly basics first. It goes through registers, memory, branching and the stack once and quickly. This course takes all of that for granted and covers the same ground again in far more depth, in NASM syntax, with every program running as a real Linux process.

Getting started with x86

The 16 registers and their halves

Memory, little endian and sizes

Bytes, words, dwords and qwords

The x86 instruction set

Effective addresses

The flags register

Sections, directives and labels

cmp and the conditional jumps

Arithmetic, logic and bits

Arrays, strings and the string instructions

The stack, push and pop

call, ret and the System V convention

Floating point and the x87 stack

SSE2 scalar and packed arithmetic

syscall and the Linux x86-64 ABI

Ports, memory-mapped devices, and kernel access

Interrupts, exceptions and signals

Moving values around

Variables in memory and constants

The bigger of two numbers

Fill an array with the numbers from 1 to 10

Sum of an array

The largest element

Length of a string

Reverse a string in place

Multiply and divide, with the remainder

Even or odd, count the set bits, multiply by shifting

A subroutine with its arguments in registers

Stack arguments and a stack frame

Recursion: factorial and Fibonacci

Print a number in any base without help