Libasm

This project involves rewriting a set of standard C library functions in x86_64 Assembly using the Intel syntax. The result is a static library, libasm.a, which can be linked to C programs to perform low-level memory and string operations.

Overview

The library is built using NASM (Netwide Assembler) and is designed for Linux environments (ELF64). It interacts directly with the kernel using system calls for I/O operations and adheres to the calling conventions required for C function interop.

Implemented Functions

The following functions have been implemented in assembly:

Function	Description	Source File
ft_strlen	Calculates the length of a string.	ft_strlen.s
ft_strcpy	Copies a string from a source buffer to a destination buffer.	ft_strcpy.s
ft_strcmp	Compares two strings lexicographically.	ft_strcmp.s
ft_write	Writes to a file descriptor (wrapper for the write system call).	ft_write.s
ft_read	Reads from a file descriptor (wrapper for the read system call).	ft_read.s
ft_strdup	Duplicates a string by allocating memory using malloc and copying data.	ft_strdup.s

Requirements

• OS: Linux (Debian-based recommended for compatibility with the provided configuration)
• Assembler: NASM
• Compiler: GCC
• Build Tool: Make

Usage

Building the Library

Use the provided Makefile to compile the sources and generate the archive file.

make

This will produce libasm.a.

Cleaning

To remove object files:

make clean

To remove object files and the library:

make fclean

To rebuild the project from scratch:

make re

Testing

A main.c file is provided to verify the functionality of the assembly routines against standard C library behavior. To compile and run the tests:

make test
./test

Docker Environment

To ensure a consistent development and testing environment, a Docker configuration is provided. This environment runs Debian Bullseye and includes all necessary build tools (NASM, GDB, GCC).

Using the Builder Script

A helper script is available to build the image and start the container with the current directory mounted to /app:

./builder.sh

Manual Docker Commands

Alternatively, you can build and run the container manually:

docker build -t libasm .
docker run -it -v $(pwd):/app libasm