AsmMinilibc — Minimal C library in x86_64 assembly

Educational and utility project: a collection of NASM (x86_64, System V) implementations of common C standard library functions. Designed for learning system assembly and for integration into small low-level projects.

Important note: this project originates from an Epitech assignment. Before any public reuse or redistribution, please verify rights and the school's policies; the license in this repository may be subject to constraints related to the origin of the files.

Features

• 100% assembly (NASM) implementations of common libc functions.
• Target ABI: System V AMD64 (Linux x86_64).
• Simple Makefile to assemble and produce libasm.so.

Included functions (examples)

• strlen (strlen.asm)
• strchr, strrchr, strstr
• strcmp, strncmp, strcspn, strpbrk

AsmMinilibc — Minimal C library in x86_64 assembly

AsmMinilibc is an educational collection of NASM (x86_64, System V) implementations of common C standard library routines. It was created to explore low-level programming and ABI-conformant implementations that can be linked from C programs.

Important note: this project originates from an Epitech assignment. Before any public reuse or redistribution, please verify rights and the school's policies; some files or templates may be subject to the school's guidelines.

Highlights

• 100% NASM implementations of selected libc routines.
• Target: Linux x86_64 (System V AMD64 ABI).
• Minimal Makefile to build a shared library (libasm.so) and object files.

Implemented examples

• strlen (strlen.asm)
• strchr, strrchr, strstr
• strcmp, strncmp, strcspn, strpbrk
• memset, memcpy, memmove

Repository layout

• *.asm — NASM source files (one function per file).
• Makefile — build rules to assemble and produce libasm.so.
• docs/ — design notes and benchmarking instructions.
• tests/ — small C tests and examples.

Build and run (quick) From the project root:

make        # assemble and generate libasm.so
make clean  # remove object files
make fclean # remove library and objects

If you don't have the toolchain installed (Debian/Ubuntu):

sudo apt update && sudo apt install -y nasm build-essential

Example: compile and run the provided simple test

gcc -L. -o tests/simple_test tests/simple_test.c -lasm
LD_LIBRARY_PATH=. ./tests/simple_test

This will print the length of a test string and verify a basic memcpy copy.

C usage (prototypes)

#include <stdio.h>
#include <stddef.h>

size_t strlen(const char *s);
void *memcpy(void *dest, const void *src, size_t n);

int main(void) {
    const char *s = "Hello, AsmMinilibc!";
    printf("len=%zu\n", strlen(s));
    return 0;
}

Testing

• See tests/simple_test.c for a minimal example. Add more test cases by compiling against -L. and linking -lasm.

Design & benchmarking

• See docs/design.md for design decisions, ABI conventions and implementation notes.
• See docs/benchmarks.md for simple benchmarking instructions and examples.

License

• This repository now includes a LICENSE file. The current license is MIT — see LICENSE for full text.