OCamLC-3 is an LC-3 assembler written in OCaml (as the name suggests).
The LC-3 or Little Computer 3 is a fictitious computer intended to teach undergraduates about a datapath while building up from simple circuits to understanding assembly and C. The instruction set architecture is relatively simple and easy to understand and is detailed here.
The CLI is a work-in-progress, but will act as a way to lex, parse, or completely assemble an input .asm file. Examples of asm files are in the tests/ directory.
The assembly process is relatively simple, as with any assembler. This is a regex-based assembler (unorthodox choice for lexing) that is comprised of 3 main steps: lexing, parsing, and assembling.
The lexing process takes an input file and reads line by line attempting to match the tokens by some priority. For example, before trying to match a label, it attempts to match an instruction (a label and instruction can both start with AND, hence the need for priority).
The lexer is detailed in src/lexer.ml built using a few productions that are matched with priorities. This returns a list of a list of lexed tokens (each list corresponding to each line).
The parsing process takes in a lexed file and parses it to ensure that instructions are properly informed. This is detailed in src/parser.ml, but essentially performs structural pattern matching on the line ensuring that instructions are followed by their neccesary requirements. For example, AND has to be followed with 2 registers and then either an additional register or a number (this number is bound checked to be imm5 in the final assembly).
The assembly process is the final step converting parsed instructions into a binary file and is detailed in src/assembler.ml.