ChunkBake: A Lua 5 Assembler

Introduction

ChunkBake is a line-oriented assembler for Lua 5 virtual machine instructions. It produces a binary chunk from assembly code, which can then be loaded and run on a Lua 5 virtual machine. ChunkBake is an educational tool; you'd probably won't be writing substantial Lua applications in assembly language form (but if you are, please pass me some of the stuff you're smoking... :-)) The syntax of ChunkBake bears a resemblance to luas assembly code, with differences. The front end was written to accomodate a variety of coding styles, e.g. registers can be written as 0, R0 or $0.

ChunkBake is written in Lua so that it is portable and easy to hack. Binary chunks that are generated can be customized with different data and field sizes and number types, so if you want to produce non-standard chunks from assembly code, this is the tool for you. You can break a lot of rules as well, and do things the Lua 5 code generator won't do. If you want a smaller assembler, a lot of code can be ripped out.

ChunkBake currently works only for Lua 5.0.2 instructions. Processing speed is brisk so there shouldn't be speed issues. For pre-1.0 releases, the syntax is open for fixes or changes. If there are better ways to write some of the assembly syntax, or if there is a defacto standard for such things, the assembler syntax MAY CHANGE for pre-1.0 releases.

Download

Main links: ChunkBake project page on LuaForge | File releases

Latest version: ChunkBake-0.7.0 (90KB zip). Win32 binary (127KB zip) available as well.

What's new?

[0.7.0] Major update:

General Lua-style expressions for most values and operands.
Equate (.equ) directive, using the global symbol table.
Unified symbol namespace, added a global symbol table.
Number conversion supports positive and negative infinity.
Fixed instruction encoding bug for setupval and getupval.
Range operator changed from '..' to '...' to accommodate expressions.
Added additional warning and error messages for certain instruction patterns.

[0.6.0] Constant declaration and operands can use nil; added a few more examples;
basic reference documentation completed.
[0.5.0] This is a preliminary release. Rudimentary but complete. Many bugs have been ironed out by the test script. Quite usable.

More Stuff

If you are looking for a disassembler for Lua 5 binary chunks, you can try ChunkSpy, which complements ChunkBake and diassembles to VM instructions, or LuaDec by Hisham Muhammad, which disassembles to Lua source code.
If you want to learn more about the instruction set of the Lua 5 virtual machine, you can read "A No-Frills Introduction to Lua 5 VM Instructions."
ChunkBake is pretty usable at the moment, as it is checked using over 400 test cases in a separate automatic test script. Many bugs have been squashed.
Generated binary chunks are targeted to Lua 5.0.2, they will not work on Lua 5.1wk5. Support for Lua 5.1 is planned (ChunkSpy already supports Lua 5.1 work 5.)
A reference manual for ChunkBake is included in the download, as are several examples based on the simple test programs found in the /test directory of Lua 5.0.2.
ChunkBake now has expressions, but some functionality is still missing, like macros and include files, so you can't really do very complex programs with the assembler yet. For more on missing stuff, see the TODO file in the download.

Acknowledgements

Thanks to the LuaForge team for hosting this material. This page was written on SeaMonkey. ChunkBake was developed using the SciTE editor.