In this experiment I aim to develop from the ground up a working compiler, assembler, linker and library, for a C-like language. I start with a minimal program capable of generating itself from its source and gradually develop higher level tools and abstractions, as follows.
This programs produced in this project are 32-bit ELF executables which run on a Linux kernel running on an Intel x86 processor. They run fine on modern 64-bit systems.
The starting point of the experiment is a tiny program for packing hexadecimal octets into binary.
This stage adds a tool to wrap a text section into a minimal ELF executable,
as well as further developing the unhex program to support labels,
references to earlier labels, and a freer input format that allows comments.
Here we introduce a light-weight assembler, written in machine code using no
forward jumps. It generates a text section that can be wrapped with the stage
1 elfify program to produce an executable.
The assembler is rewritten in assembler language and is joined by a linker, which together allow for separate compilation units.
The project's first compiler is added at this stage. Its input language is a
typeless subset of C similar to B, and it emits assembler language. We also
build a startup file (crt0.o) and the start of a simple C library.
The compiler is rewritten in its source language, and a type system added. We
use it to implement a fairly standards-compliant C preprocessor, and a
compiler driver (cc) that spawns the cpp, ccx (the compiler proper),
as and ld. Finally, cmp is a POSIX compliant utility to compare two
files, which is used in a preproccesor test suite.
The code in this project is copyright (C) Richard Smith, 2009–2021, and
is licensed for use under version 3 or later of the GNU General Public
License, a copy of which can be found in the file LICENCE.txt.
The documentation in these README files is licensed under the
Creative Commons BY-NC-SA licence,
version 4.