This is a simple LC-3 assembler and linker written from scratch in Java (Java because CS 1331 is a prereq). Pulkit wrote most of it but then Austin lightly sabotaged it.
The purpose of releasing this assembler to students is to give you the chance to read the source of a 2-pass assembler and see how it would work. It is not intended to be perfect — much error handling is missing, for example. Same for the linker.
First, compile the utilities in this repository:
javac *.java
To assemble some LC-3 assembly into an object file (will create the object file
my_assembly.obj and the symbol table my_assembly.sym):
java LC3asm my_assembly.asm
To link object files (links object files my_assembly.obj and my_library.obj
together into linked.obj. Note you will need to assemble my_library.asm
into my_library.obj first):
java LC3link my_assembly.obj my_library.obj -o linked.obj
Finally, to convert a human-readable object file to an object file usable in
LC3Tools (will create a file named linked.lc3tools.obj you should open
in LC3Tools — click the chip symbol in the top right and then the folder symbol
on the left):
java ObjToLC3Tools linked.obj
As a bonus, you can disassemble an object file back into assembly like
this (will create linked.dis.asm. The -x optionally writes .fills in
hexadecimal rather than the default of interpreting the word as 16-bit two's
complement):
java LC3disasm -x linked.obj
Try all those commands and see what happens! Look at the generated files! And
look at the source code in all the *.java files, too! We provided
my_library.asm and my_assembly.asm in this repository for your convenience.
If you use Linux or macOS, you may find these shell aliases useful for invoking the assembler, linker, etc. outside of this repository:
lc3asmrepo=/path/to/this/repository
alias lc3as='java -cp $lc3asmrepo LC3asm'
alias lc3ld='java -cp $lc3asmrepo LC3link'
alias lc3conv='java -cp $lc3asmrepo ObjToLC3Tools'
alias lc3disas='java -cp $lc3asmrepo LC3disasm'
If you are on Windows, please see this helpful page.