https://briancallahan.net/blog academic, developer, with an eye towards a brighter techno-social life https://briancallahan.net/blog/20251216.html Instructions to get a small embedded ARM64 device working with the latest FreeBSD operating system Tue, 16 Dec 2025 00:00:00 +0000 https://briancallahan.net/blog/20250901.html Learn how to cross-compile a native GCC toolchain Mon, 01 Sep 2025 00:00:00 +0000 https://briancallahan.net/blog/20250817.html Learn how to cross-compile a native GCC toolchain Sun, 17 Aug 2025 00:00:00 +0000 https://briancallahan.net/blog/20250813.html Discovery and diagnosis of a bug hiding in plain sight Wed, 13 Aug 2025 00:00:00 +0000 https://briancallahan.net/blog/20250516.html Step-by-step process to get pkgsrc working on modern AIX Fri, 16 May 2025 00:00:00 +0000 https://briancallahan.net/blog/20250329.html Step-by-step process to get a modern GCC on an old Mac OS X Sat, 29 Mar 2025 00:00:00 +0000 https://briancallahan.net/blog/20250222.html Testing VMWare Fusion and the Apple virtualization framework with each *BSD Sat, 22 Feb 2025 00:00:00 +0000 https://briancallahan.net/blog/20250112.html Getting a compiler written in its own langauge bootstrapped for a new platform Sun, 12 Jan 2025 00:00:00 +0000 https://briancallahan.net/blog/20241216.html A quick tutorial for setting up a complete cross compiling envinroment using a FreeBSD/amd64 host and macOS/aarch64 target Mon, 16 Dec 2024 00:00:00 +0000 https://briancallahan.net/blog/20241212.html A walkthrough to bootstrap GDC on macOS/aarch64 Thu, 12 Dec 2024 00:00:00 +0000 https://briancallahan.net/blog/20240609.html A walkthrough to bootstrap DMD on OpenIndiana Sun, 09 Jun 2024 00:00:00 +0000 https://briancallahan.net/blog/20240306.html A walkthrough to get Intel oneAPI DPC++/C++ to output native binaries for FreeBSD Wed, 06 Mar 2024 00:00:00 +0000 https://briancallahan.net/blog/20240122.html How to use LLVM as the assembler for GCC, for FreeBSD and other systems Mon, 22 Jan 2024 00:00:00 +0000 https://briancallahan.net/blog/20240101.html A walkthrough to get Oracle Developer Studio 12.6 to output native binaries for FreeBSD Mon, 01 Jan 2024 00:00:00 +0000 https://briancallahan.net/blog/20231119.html Adding the experimental LLVM targets to the OpenBSD LLVM packages Sun, 11 Nov 2023 00:00:00 +0000 https://briancallahan.net/blog/20230813.html My ordeal trying to get mold to be /usr/bin/ld on OpenBSD Sun, 13 Aug 2023 00:00:00 +0000 https://briancallahan.net/blog/20230723.html Can the Sun assembler and Yasm be used with PCC? Sun, 23 Jul 2023 00:00:00 +0000 https://briancallahan.net/blog/20230705.html Teaching an old compiler new tricks. Wed, 05 Jul 2023 00:00:00 +0000 https://briancallahan.net/blog/20230703.html The (mis)adventures of installing Developer Studio on Illumos despite Oracle's many attempts to stop me. Mon, 03 Jul 2023 00:00:00 +0000 https://briancallahan.net/blog/20230626.html Can we build all ten GCC langauge frontends on OpenBSD? Mon, 26 Jun 2023 00:00:00 +0000 https://briancallahan.net/blog/20221219.html Reviewing the state of the new Modula-2 and Rust frontends for GCC on OpenBSD. Mon, 19 Dec 2022 00:00:00 +0000 https://briancallahan.net/blog/20221113.html Reflections on the new CySA+ exam I took today. Sun, 13 Nov 2022 00:00:00 +0000 https://briancallahan.net/blog/20220704.html Demonstrating the C compiler that lives inside a D compiler. Mon, 04 Jul 2022 00:00:00 +0000 https://briancallahan.net/blog/20220629.html Discussing porting chibicc and kefir to OpenBSD. Wed, 29 Jun 2022 00:00:00 +0000 https://briancallahan.net/blog/20220427.html A walkthrough on porting a brand new language to OpenBSD. Wed, 27 Apr 2022 00:00:00 +0000 https://briancallahan.net/blog/20220426.html My thoughts on trying out the V programming language and its first-party apps for the first time. Tue, 26 Apr 2022 00:00:00 +0000 https://briancallahan.net/blog/20220418.html Step-by-step instructions to get OpenBSD/riscv64 running on QEMU. Mon, 18 Apr 2022 00:00:00 +0000 https://briancallahan.net/blog/20220417.html We study how LLVM and GCC optimize increments and decrements and teach those optimizations to our QBE optimizer. Sun, 17 Apr 2022 00:00:00 +0000 https://briancallahan.net/blog/20220406.html Let's teach the Tiny C Compiler to emit better code. Wed, 06 Apr 2022 00:00:00 +0000 https://briancallahan.net/blog/20220402.html Finishing up our peephole optimizer from the previous blog post. Sat, 02 Apr 2022 00:00:00 +0000 https://briancallahan.net/blog/20220330.html Introducing O, a peephole optimizer to fix up missed opportunities in QBE. Wed, 30 Mar 2022 00:00:00 +0000 https://briancallahan.net/blog/20220321.html Trying out the new GCC COBOL frontend on OpenBSD. Mon, 21 Mar 2022 00:00:00 +0000 https://briancallahan.net/blog/20220222.html Reflections on the new Linux+ exam I took last week. Tue, 22 Feb 2022 00:00:00 +0000 https://briancallahan.net/blog/20220220.html Abusing the C preprocessor for fun and profit. Sun, 20 Feb 2022 00:00:00 +0000 https://briancallahan.net/blog/20220205.html Reflections on the new Project+ exam I took today. Sat, 05 Feb 2022 00:00:00 +0000 https://briancallahan.net/blog/20211204.html Learning how to get the vbcc C compiler up and runnin on OpenBSD and able to compile the oksh shell. Sat, 04 Dec 2021 00:00:00 +0000 https://briancallahan.net/blog/20211031.html Quick post to keep everyone updated on the latest OpenBSD and D news from me. Sun, 31 Oct 2021 00:00:00 +0000 https://briancallahan.net/blog/20211020.html A short post writing down how to create a bootstrap LDC compiler for the OpenBSD port. Wed, 20 Oct 2021 00:00:00 +0000 https://briancallahan.net/blog/20211013.html Previewing my DConf 2021 talk about D on OpenBSD by discussing how the new DMD package came to be. Wed, 13 Oct 2021 00:00:00 +0000 https://briancallahan.net/blog/20211010.html Getting inconclusive numbers about the definitively best Unix shell. Sun, 10 Oct 2021 00:00:00 +0000 https://briancallahan.net/blog/20210911.html A detailed write-up on porting J to OpenBSD. Sat, 11 Sep 2021 00:00:00 +0000 https://briancallahan.net/blog/20210906.html Beginning a new compiler-writing adventure in which we will produce a self-hosting PL/0 compiler. Mon, 06 Sep 2021 00:00:00 +0000 https://briancallahan.net/blog/20210829.html Learning the QBE Intermediate Language via writing a small Brainfuck compiler directly in QBE IR. Sun, 29 Aug 2021 00:00:00 +0000 https://briancallahan.net/blog/20210826.html Adding the last few pieces needed for a finished PL/0 compiler. Thu, 26 Aug 2021 00:00:00 +0000 https://briancallahan.net/blog/20210822.html Adding array support to our PL/0 compiler. Sun, 22 Aug 2021 00:00:00 +0000 https://briancallahan.net/blog/20210819.html Adding basic input and output routines to our PL/0 compiler. Thu, 19 Aug 2021 00:00:00 +0000 https://briancallahan.net/blog/20210818.html Writing a code generator for our PL/0 compiler. Wed, 18 Aug 2021 00:00:00 +0000 https://briancallahan.net/blog/20210817.html Building a simple automated testing framework for our PL/0 compiler. Tue, 17 Aug 2021 00:00:00 +0000 https://briancallahan.net/blog/20210816.html Writing a parser for our PL/0 compiler. Mon, 16 Aug 2021 00:00:00 +0000 https://briancallahan.net/blog/20210815.html Writing a complete lexer for our PL/0 compiler. Sun, 15 Aug 2021 00:00:00 +0000 https://briancallahan.net/blog/20210814.html The beginning of a new series where we will write a simple PL/0 to C compiler from scratch. Sat, 14 Aug 2021 00:00:00 +0000 https://briancallahan.net/blog/20210802.html Walking through my first OpenBSD port from ten years ago and revising it to today's standards. Mon, 02 Aug 2021 00:00:00 +0000 https://briancallahan.net/blog/20210801.html An amateur radio musing on how you can further the state of the art. Sun, 01 Aug 2021 00:00:00 +0000 https://briancallahan.net/blog/20210710.html Demonstrating lots of assembly language tricks to optimize for size. Sat, 10 Jul 2021 00:00:00 +0000 https://briancallahan.net/blog/20210627.html Step-by-step how I thought through and wrote a moderately difficult OpenBSD port for the TIC-80. Sun, 27 Jun 2021 00:00:00 +0000 https://briancallahan.net/blog/20210609.html A detailed tour of a CP/M and MS-DOS linker and object file format of our own creation. Wed, 09 Jun 2021 00:00:00 +0000 https://briancallahan.net/blog/20210606.html Discussing a new hit program developed 40 years too late. Sun, 06 Jun 2021 00:00:00 +0000 https://briancallahan.net/blog/20210604.html Porting a Unix program to MS-DOS for fun. Fri, 04 Jun 2021 00:00:00 +0000 https://briancallahan.net/blog/20210529.html A how-to on basic profiler usage, improving the performance of our assembler. Sat, 29 May 2021 00:00:00 +0000 https://briancallahan.net/blog/20210522.html Compiling the GNU D Compiler to OpenBSD/armv7. Sat, 22 May 2021 00:00:00 +0000 https://briancallahan.net/blog/20210520.html Walking through how I ported the GNU D Compiler to OpenBSD/arm64. Thu, 20 May 2021 00:00:00 +0000 https://briancallahan.net/blog/20210425.html Building a Brainfuck compiler with backends for amd64, i386, Z80 and C. Sun, 25 Apr 2021 00:00:00 +0000 https://briancallahan.net/blog/20210415.html Part 9, Finishing our assembler with some pseudo-ops. Thu, 15 Apr 2021 00:00:00 +0000 https://briancallahan.net/blog/20210414.html Part 8, teaching the assembler about logical shifts, incrementers and decrementers, and the lxi and mvi instructions. Wed, 14 Apr 2021 00:00:00 +0000 https://briancallahan.net/blog/20210413.html Part 7, teaching the assembler about push, pop, jump/call/ret instructions. Tue, 13 Apr 2021 00:00:00 +0000 https://briancallahan.net/blog/20210412.html Part 6, teaching the assembler about mov and arithmetic instructions. Mon, 12 Apr 2021 00:00:00 +0000 https://briancallahan.net/blog/20210411.html Part 5, translating nop assembly instructions into 0x00 bytes. Sun, 11 Apr 2021 00:00:00 +0000 https://briancallahan.net/blog/20210410.html Part 4, turning lines of Intel 8080 assembly language into their individual tokens. Sat, 10 Apr 2021 00:00:00 +0000 https://briancallahan.net/blog/20210409.html Part 3, understanding assembler passes and setting up our error handler. Fri, 09 Apr 2021 00:00:00 +0000 https://briancallahan.net/blog/20210408.html Part 2, planning the Z80 assembler. Thu, 08 Apr 2021 00:00:00 +0000 https://briancallahan.net/blog/20210407.html Part 1 of a new series in which we create an assembler and disassembler for the Z80 CPU. Wed, 07 Apr 2021 00:00:00 +0000 https://briancallahan.net/blog/20210403.html Discussing the process of getting a working gm2 on OpenBSD. Sat, 03 Apr 2021 00:00:00 +0000 https://briancallahan.net/blog/20210327.html A detailed demonstration of a D screenshot utility from zero to complete. Sat, 27 Mar 2021 00:00:00 +0000 https://briancallahan.net/blog/20210320.html The (condensed) story of how I got the GNU D Compiler working on OpenBSD. Sat, 20 Mar 2021 00:00:00 +0000 https://briancallahan.net/blog/20210311.html Quick plug for my talk at BSidesROC 2021. Thu, 11 Mar 2021 00:00:00 +0000 https://briancallahan.net/blog/20210215.html Presented in a table. Mon, 15 Feb 2021 00:00:00 +0000 https://briancallahan.net/blog/20210214.html The story of how the Tiny C Compiler got ported to OpenBSD, from my perspective. Sun, 14 Feb 2021 00:00:00 +0000 https://briancallahan.net/blog/20201124.html Explore how to leverage standard interfaces to create truly portable programs. Tue, 24 Nov 2020 00:00:00 +0000 https://briancallahan.net/blog/20201118.html A look at a new programming language, Cowgol, designed for 8-bit CPUs. Wed, 18 Nov 2020 00:00:00 +0000 https://briancallahan.net/blog/20201104.html A free article to inspire you to share your ham radio adventures. Sat, 04 Nov 2020 00:00:00 +0000 https://briancallahan.net/blog/20201010.html Sharing my dream with you. Sat, 10 Oct 2020 00:00:00 +0000 https://briancallahan.net/blog/20200926.html How I managed to do the ham radio hobby "wrong." Sat, 26 Sep 2020 00:00:00 +0000 https://briancallahan.net/blog/20200827.html Introducing a new series in which we will learn how to design and implement a data transmit and receive protocol. Thu, 27 Aug 2020 00:00:00 +0000 https://briancallahan.net/blog/20200825.html What I gained by shrinking my world. Tue, 25 Aug 2020 00:00:00 +0000 https://briancallahan.net/blog/20200816.html I wrote the absolute minimum that could possibly be considered a text editor. Sun, 16 Aug 2020 00:00:00 +0000 https://briancallahan.net/blog/20200812.html I hand-compiled some C code to see if I could do better than my C compiler. Wed, 12 Aug 2020 00:00:00 +0000 https://briancallahan.net/blog/20200808.html Have you ever wondered how Unix programs know what argc and argv are? Read on to find out. Sat, 08 Aug 2020 00:00:00 +0000 https://briancallahan.net/blog/20200806.html Comparing compiler numbers, then discarding them as a distraction. Thu, 06 Aug 2020 00:00:00 +0000 https://briancallahan.net/blog/20200803.html A very deep dive into a very small codebase. Mon, 03 Aug 2020 00:00:00 +0000 https://briancallahan.net/blog/20200726.html Explaining my motivations for writing my newest Free Software project. Sun, 26 Jul 2020 00:00:00 +0000 https://briancallahan.net/blog/20200615.html I decided to play the intro CTF to TryHackMe in order to begin to get a feel for how people think about cybersecurity pedagogy. Mon, 15 Jun 2020 00:00:00 +0000