In-browser LC-3 toolchain and queue management for symbolic testing

Abstract

In early computer systems education, making the testing and debugging environment easily accessible is critical for enabling students to gain skill and confidence in programming. Real-time feedback on assignments and guidance during the development process is also beneficial in helping them to identify bugs in their code. Unfortunately, many of the tools and techniques in use today rely on schools’ IT support to be set up, or on attention from course staff to provide feedback to students. In this thesis, we investigate the possibility of translating an existing C implementation of LC-3 assembler and simulator into JavaScript using WebAssembly. By doing that, the LC-3 toolchain can be ported to a browser-based environment and grant students an easily accessible place for their programming and debugging. To further aid students on their code verification and give them timely feedback on limited computing resources, we also designed and built a queuing system and a related scheduling policy for running symbolic testing on programs submitted through students’ Git repositories. In the Fall 2020 semester, we deployed the whole coding, debugging and testing pipeline and introduced our system to over 100 ECE 220 students at the ZJU-UIUC Institute. Discussion about students’ usage behavior and submission statistics is also presented.