Reverse engineer and reimplement C++ virtual file system encryption library in RustApps for iOS and macOS to unlock and manage ArmorLock encrypted NVMe SSDs via USB HID and BluetoothManufacturing test and validation tool for ArmorLock encrypted NVMe SSDsCustom USB HID device for Nordic nrf52 series SoC

Custom enhancements for Clozure Common Lisp compilerApplication development in Common LispmacOS application development

Concur is a provider of integrated travel and expense solutions, delivered using the software-as-a-service model.I was a member of a team developing new foundational services (e.g., identity management, authentication, and so forth) on which Concur's business applications are being built.These services are web services with RESTful style interfaces. Technologies used include Clojure, various SQL and NoSQL databases, GitHub, Python (for API tests), and the usual panoply of other assorted supporting tech. Services typically ran on AWS-hosted Linux servers.Additionally, I promoted the interactive and incremental style of development traditionally used by Lisp and Lisp family languages, Clojure being a Lisp descendant.

Clozure Associates is a Common Lisp consulting company, and also has supported the development of Clozure Common Lisp, an open-source Common Lisp implementation.A large part of my work was to enhance and maintain Clozure CL on the various operating systems (macOS, Linux, FreeBSD, Solaris, Windows) and processor architectures (x86, ARM, PowerPC) that it runs on.Clozure CL is mostly written in Common Lisp, but there is an important part (called the lisp kernel) that is written in C and a fair amount of processor-specific assembly language. The lisp kernel provides the run-time environment for running lisp code. It uses quite a lot of low-level functionality exposed by the operating system: address space management, signal/exception handling, thread management, and so forth.I designed and implemented the 32-bit x86 port of the Clozure CL Lisp compiler and runtime, based on the existing x86-64 port. * Updated the x86 assember and disassembler to support 32-bit x86. * Added 32-bit x86 support to the compiler back end. Wrote new code generation primitives. * Wrote assembly language code to support foreign function calls, bignums, and so forth. * Adapted the garbage collector to support the data representation of 32-bit x86 Lisp objects and to support the dyanamic register-partitioning scheme that the 32-bit x86 port uses.Installed and managed Buildbot (a continuous integration system) for the Clozure CL project. Configured and customized it using Python.Contributed to numerous client projects.Configured and managed numerous project infrastructure services such as mail (including mailing lists), various web sites, Trac (for bug tracking), Subversion, and so forth, both for Clozure CL itself and for client projects. Clozure CL sources are now on GitHub, but the legacy Trac and Subversion repository are still online.Performed release engineering for the (very) roughly bi-annual releases of Clozure CL.

Contractor at NASA Glenn Research Center. Expert in Unix, Mac OS X, IP networking, and computer security. Developed agency-level IT interoperability standards.