lace

lace is an all-in-one LC3 (Little Computer 3) assembly toolchain. lace currently supports compiling, checking, running and placing a watch on LC3 assembly files. It will support fancy convenience features like a formatter and (probably) running with a copy of the original OS. Some features are missing!

Commands

• run: assemble and run a file - all in one command.
• compile: creates a binary file with a .lc3 extension. Note that lace cannot currently run these files, so you may need a different LC3 virtual machine to test them out until that is implemented.
• check: verifies that your file is correct without outputting it or running it.
• watch: runs check for a specified file on save while you develop. Neat!
• fmt: (planned) formats your .asm file to fit my arbitrary style guide.
• clean: (planned) used to clean debug artifacts that will be implemented in the future.

Instruction set extension

LC3 is unfortunately limited in terms of functionality, with the absence of a stack being the most painful missing feature. Luckily, LC3 also comes with a spare opcode (0b1101/0xD), which I have used to implement stack-based instructions on top of the existing set. The new instructions are:

• call - call a subroutine using a label with 10 bits of precision, and push program counter to stack (usage: call label)
• rets - pop address off the stack and set program counter to its value (usage: rets after calling subroutine)
• push - push the contents of a register onto the stack (usage: push r0)
• pop - pop the top value of the stack off into a register (usage: pop r0 after pushing)

Please note that these instructions will only function when using the lace virtual machine and run command.

Traps

There are a few extra traps that should make debugging a lot nicer! Please note that they will not perform as expected when you run your binaries with other virtual machines.

• putn: print the contents of r0 to console. That's not usually very easy to do, and you should probably learn why!
• reg: print the contents of every register to console. Currently only supports u16 formatting.

Work in progress

There are several features and fixes under development:

• Showing multiple errors per compilation
• Different number formats for console output
• File formatting
• Debug symbols
• A step-through debugger (big one!)

Check the repo for updates as it is under active development.

Installation

For now, please use cargo to get set up, as there are no official releases. Check in often for the latest updates! If you are unsure what cargo is, check out this help page. Alternatively, there is a flake.nix available with a Rust development shell, if you have Nix set up.

To install, follow the steps below:

git clone https://github.com/rozukke/lace.git
cd lace
cargo install --path .

You should, as a result, have the lace binary available in your PATH.

Examples

Some examples are available under the tests/files directory for testing purposes. You can run them with LC3, e.g. lace run tests/files/hw.asm.

Contributors

A huge thank you to @dxrcy for various additions and bugfixes, including continued work on the debugger implementation!

License

Copyright (c) 2024 Artemis Rosman

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.