Portfolio – Alexander Payne


Here are some faded aspects of my hobby. Other than my F/LOSS work, these largely have not been touched since 2016.

Cosmonaut

Cosmonaut wass a long-term, extremely incomplete, personal project on which I worked, inspired by things I encounter at my day job. It began as an educational project for me to learn how to write a parser, and then aimed to provide a complement to the COSMOS project by Ball Aerospace.

It was able to parse COSMOS definition files and create a dictionary in Rust whose members can be used to serialize a record into the bitstream that the COSMOS text defines. I wrote the bitvec crate specifically to address the fact that COSMOS definitions of wire protocols permit, and we use at work, fields that are a combination of:

  • not an even multiple of bytes in width
  • not guaranteed to start or end on a byte boundary
  • able to cross a byte boundary

These constraints are impossible to cleanly service in standard Rust, and the other bit-vector libraries I encountered did not support such manipulation. Furthermore, because I work in esoteric hardware, the endianness of bits in an element matters to the network layer, so I need to bring both bitvec and endian_trait into play in order to match the bitstream that actually transfers over the wire.

Rust Crates

These are described in detail in their own section

This Website

My talents and education lie primarily in architecture and engineering. I firmly believe in the importance of a broad skill set and mastery of new topics. I designed this website myself to understand design and UI concepts. I also improved my understanding of systems administration and networking by hosting it myself.

The code governing this site is available on GitHub, as are the pages themselves.

Senior Design

My Senior Design project is the largest and most complex project I have completed to date. The code itself is available on my GitHub profile. Our team also created a YouTube video summary of the completed vehicle. I can provide other documents such as our design specifications, presentations, and reports upon request.

I designed a robust Real-Time Operating System capable of using both scheduled and interrupt-driven tasks to drive an autonomous vehicle. I also wrote the hardware drivers for my peripherals – GPS, compass, ultrasonic sensors, and motors – and the RTOS modules which consumed them.

My software design received high marks from my professors, and the system interfaced flawlessly with the hardware. Our public demonstration was a complete success, and we were able to navigate our route fully without colliding with pedestrians or straying off of the sidewalk.

The software I engineered demonstrates my excellent grasp of the software design patterns and engineering principles requisite in any complex project.

MIPS CPU

For my Logic and Computer Design class, I implemented a 32-bit pipelined MIPS CPU in Verilog. I am not able to showcase the code from that class due to some licensing constraints. My design included features such as:

  • Five-stage pipeline with operand forwarding and stall detection
  • 32-element register file with half-cycle latency
  • ALU with replaceable arithmetic logic
    • Ripple-carry addition at first
    • Look-ahead-carry addition
    • Finally, Kogge-Stone addition
  • RAM access (we also designed the RAM banks and controllers)
  • von Neumann architecture: I was able to load and execute basic MIPS object code with my project, and support self-modifying program execution.
  • Access to peripheral devices using drivers I wrote

Hermaeus

Hermaeus (homepage, source code, Gem page) is a scripted reddit client designed to archive posts. It operates by processing index pages and retrieving the content they reference. Hermaeus is capable of reformatting the downloaded text and storing it to disk; future goals include storing texts in SQL and NoSQL databases, and powering a website for public browsing of the archive it manages.

One of my design goals with Hermaeus is to have it be usable by non-technical people, namely, the moderators of a reddit community I frequent and for whom it was designed. Hermaeus achieves this goal with an easy-to-use launcher script.

Computer Assembly and System Administration

I built my server and desktop. Both are currently out of service, as they are eight and six years old and badly worn. When they lived, they ran Windows and Arch Linux.

/r/teslore CSS

I architected the stylesheet for /r/teslore. The source code for the current sheet is here; it is several years old and showing it. I am rebuilding the sheet in my spare time, but unfortunately am not at liberty to publicize any part of the code yet.