Axiom

A self-contained AArch64/ELF toolchain built from the ground up.

Axiom is a hobbyist systems programming project focused on implementing the core components of a compilation and linking pipeline. It is written in pure C with zero dependencies beyond libc and the standard elf.h headers.

Project Structure

The project is divided into four primary components:

Component	Description	Status
libax/	The "heart" of the project. Contains shared logic, custom vector implementations, ELF object manipulation, and common utilities.	Stable
axas/	A custom assembler that transforms assembly source into ELF object files. Supports a subset of AArch64 instructions and standard directives.	Functional
axld/	A minimalist linker. Currently capable of taking a single Axiom-generated object file and producing a valid executable.	WIP (Single Object)
axcc/	The planned C compiler for the Axiom ecosystem.	Planned

Getting Started

Prerequisites

• A C compiler (GCC or Clang)
• GNU Make
• A Linux environment (for ELF support and AArch64 testing)

Building

The project uses a top-level Makefile to orchestrate the build of all sub-components:

git clone https://github.com/wk1093/axiom
cd axiom
make

Binaries for the assembler and linker will be generated in their respective bin/ or build/ directories.

Usage

Assembling

To transform an assembly file into an ELF object:

./axas/bin/axas input.s -o output.o

Linking

To create an executable from your object file:

./axld/bin/axld output.o -o my_program

Current Limitations

Axiom is a work-in-progress and currently operates under the following constraints:

• axas: Only supports a specific subset of the AArch64 instruction set.
• axld: Supports linking only a single object file. It does not currently support static (.a) or dynamic (.so) libraries.
• Architecture: Primarily focused on AArch64 (ARM64) systems.

Philosophy

• Zero Dependencies: No third-party libraries. If I need a data structure, I build it.
• Transparency: Code is written to be readable and to serve as a reference for how ELF files are structured and manipulated.
• Low-Level Control: Direct manipulation of section headers, symbol tables, and relocation entries.

New Instructions

New instructions can be added by only modifying two different places:

• libax/include/ax_instr_def.h: X-macros containing main information about an instruction.
• libax/src/axas_assembler.c: If the instruction has any special rules about how it is assembled.

TODO

• AXLIBC: Add support for arguments (stdlib stuff)
• AXAS: Add more instructions to assembler
• AXAS/AXLD: Add support for all sections (.rodata, .bss, etc.)
• AXLD: Add support for multiple object files
• AXLD: Add supprt for .a library files (statically linked)
• AXLD: HARD: Add support for dynamically linking
• AXCC: HARD: Write C compiler