This is example C scaffolding and toolchain setup guidance for following jmeiners' LC-3 VM tutorial, set up in a way that I think is easier to follow. The original tutorial puts a lot of setup code near the end, so it can be hard to check your progress partway through.
The tutorial's enums, setup code, and memory management are provided so you don't have to copypasta everything in from the tutorial. Just instruction set implementations are left as an exercise for the reader. However, I still recommend going through all the scaffolding code line by line to get the educational benefits.
About LC-3 (Little Computer 3)
LC-3 is an educational 16-bit computer architecture with 16 opcodes and 8 general-purpose registers. However, R7 is usually reserved for return addresses. Data is stored in two's complement representation. Some I/O operations are provided through TRAP instructions.
Install gcc. You will use gcc to compile your C file into an executable.
- MacOS:
brew install gcc - Unix:
sudo apt-get install gcc
If you want to be able to write any of your own intermediate test cases in Assembly, set up the LC-3 tools.
Follow their setup instructions. You should then be able to run the assembler on an assembly file, like so:
lc3as roms/hello.asm
Assembly files and assembled roms live in roms/.
To run a rom on the VM, pass the .obj file path to the VM executable.
./lc3-vm roms/hello.obj
If you have not implemented anything yet, you should see an error message about an op not being implemented.
If you installed the LC-3 tools, you can use my Make targets as shorthand to
assemble new roms. For example, to reassemble and run roms/hello.asm, do
make run rom=roms/hello.
When you make changes to the LC-3 implementation, you'll want to recompile the C code to an executable.
You can use make compile as shorthand. To see what it does, read Makefile.