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https://github.com/kavicastelo/assembly_basics
This guide is designed to help you learn assembly language from the ground up, focusing on the 64-bit Windows architecture. We'll cover everything from setting up your environment to understanding registers and writing basic programs.
https://github.com/kavicastelo/assembly_basics
asmx86 assembly basics gcc-complier low-level mingw-w64 nasm
Last synced: about 9 hours ago
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This guide is designed to help you learn assembly language from the ground up, focusing on the 64-bit Windows architecture. We'll cover everything from setting up your environment to understanding registers and writing basic programs.
- Host: GitHub
- URL: https://github.com/kavicastelo/assembly_basics
- Owner: kavicastelo
- Created: 2024-07-25T18:18:36.000Z (2 months ago)
- Default Branch: master
- Last Pushed: 2024-07-30T19:05:26.000Z (about 2 months ago)
- Last Synced: 2024-09-24T22:51:52.266Z (about 14 hours ago)
- Topics: asmx86, assembly, basics, gcc-complier, low-level, mingw-w64, nasm
- Language: Assembly
- Homepage: https://kavicastelo.github.io/assembly_basics/
- Size: 50.8 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
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README
# Assembly Language Guide for Windows 64-bit
## Introduction
This guide is designed to help you learn assembly language from the ground up, focusing on the 64-bit Windows
architecture. We'll cover everything from setting up your environment to understanding registers and writing basic
programs. High-level programming language comparisons are included to make concepts more understandable.
## Table of Contents
1. [Setting Up the Environment](#setting-up-the-environment)
2. [Basic Syntax and Structure](#basic-syntax-and-structure)
3. [Registers](#registers)
4. [Simple Input and Output](#simple-input-and-output)
5. [Arithmetic Operations](#arithmetic-operations)
6. [Control Flow](#control-flow)
7. [Functions and Calling Conventions](#functions-and-calling-conventions)
8. [Learning Strategies](#learning-strategies)
## Setting Up the Environment
1. **Install NASM:** Download and install NASM from the [official site](https://www.nasm.us).
2. **Install MinGW or GCC:** Download and install MinGW or GCC for Windows.
3. **Set up IntelliJ IDEA:** Use IntelliJ IDEA with the necessary plugins to support assembly language.
## Basic Syntax and Structure
An assembly program is divided into sections:
- **.data:** Contains initialized data
- **.text:** Contains executable code
- **.bss:** Contains uninitialized data
### Example
```asm
section .data
hello db 'Hello, world!', 0
section .text
global _start
_start:
; Your code here
```
## Registers
Registers are limited storage locations in the CPU, each with specific purposes.
### General-Purpose Registers
- **RAX, RBX, RCX, RDX:** Arithmetic operations, loop counters, function returns.
- **RSP, RBP, RSI, RDI:** Stack pointer, base pointer, source index, destination index.
- **R8, R9, R10, R11, R12, R13, R14, R15:** Reserved for future use.
- **RIP:** Points to the next instruction to execute.
- **RFLAGS:** CPU flags.
### Segment Registers
- **CS, SS, DS, ES, FS, GS:** Segment selectors.
### Example
C Code:
```c
int main() {
int a = 5;
int b = 10;
int sum = a + b;
return sum;
}
```
Assembly Code:
```asm
section .text
global _start
_start:
mov rax, 5 ; a = 5
mov rbx, 10 ; b = 10
add rax, rbx ; sum = a + b
mov rdi, rax ; return sum
call ExitProcess
```
## Simple Input and Output
### Printing a String
C Code:
```c
#include
int main() {
printf("Hello, World!");
return 0;
}
```
Assembly Code:
```asm
section .data
hello db 'Hello, World!', 0
section .text
global _start
extern GetStdHandle
extern WriteConsoleA
extern ExitProcess
_start:
mov rcx, -11 ; STD_OUTPUT_HANDLE
call GetStdHandle
mov rcx, rax ; handle to stdout
mov rdx, hello ; pointer to string
mov r8, 13 ; string length
lea r9, [rsp+8] ; dummy variable
call WriteConsoleA
xor rcx, rcx ; exit code 0
call ExitProcess
```
## Arithmetic Operations
### Addition Example
C Code:
```c
int add(int a, int b) {
return a + b;
}
```
Assembly Code:
```asm
section .text
global _start
_start:
mov rax, 5 ; a = 5
mov rbx, 10 ; b = 10
add rax, rbx ; result = a + b
call ExitProcess
```
## Control Flow
### Loop Example
C Code:
```c
int sum_n(int n) {
int sum = 0;
for (int i = 1; i <= n; i++) {
sum += i;
}
return sum;
}
```
Assembly Code:
```asm
section .text
global _start
_start:
mov rcx, 10 ; n = 10
mov rax, 0 ; sum = 0
mov rbx, 1 ; i = 1
loop_start:
add rax, rbx ; sum += i
inc rbx ; i++
cmp rbx, rcx
jle loop_start ; if i <= n, repeat
call ExitProcess
```
## Functions and Calling Conventions
### Function Example
C Code:
```c
int multiply(int a, int b) {
return a * b;
}
int main() {
int result = multiply(5, 10);
return result;
}
```
Assembly Code:
```asm
section .text
global _start
extern multiply
_start:
mov rcx, 5 ; a = 5
mov rdx, 10 ; b = 10
call multiply
; result is in rax
call ExitProcess
multiply:
imul rax, rcx, rdx
ret
```
## Learning Strategies
- **Start Small:** Begin with simple programs and gradually increase complexity.
- **Use Debuggers:** Tools like `gdb` can help you step through your code and understand what's happening.
- **Read Documentation:** Manuals and tutorials specific to x86-64 assembly can be very helpful.
- **Practice Regularly:** Writing and experimenting with code is the best way to learn.