Software Development

787 Articles

Procedurally Generated Trees

November 20, 2020 by 16 Comments

As the leaves fall from the trees here in the Northern Hemisphere, we are greeted with a clear view of the branches and limbs that make up the skeleton of the tree. [Nicolas McDonald] made a simple observation while looking at trees, that the sum of the cross-sectional area is conserved when a branch splits. This observation was also made by Leonardo Da Vinci (according to Pamela Taylor’s Da Vinci’s Notebooks). Inspired by the observation, [Nicolas] decided to model a tree growing for his own curiosity.

The simulation tries to approximate how trees spread nutrients. The nutrients travel from the roots to the limbs, splitting proportionally to the area. [Nicolas’] model only allows for binary splits but some plants split three ways rather than just two ways. The decision on where to split is somewhat arbitrary as [Nicolas] hasn’t found any sort of rule or method that nature uses. It ended up just being a hardcoded value that’s multiplied by an exponential decay based on the depth of the branch. The direction of the split is determined by the density of the leaves, the size of the branch, and the direction of the parent branch. To top it off, a particle cloud was attached at the end of each branch past a certain depth.

By tweaking different parameters, the model can generate different species like evergreens and bonsai-like trees. The code is hosted on GitHub and we’re impressed by how small the actual tree model code is (about 250 lines of C++). The power of making an observation and incorporating it into a project is clear here and the results are just beautiful. If you’re looking for a bit more procedurally generation in your life, check out this medieval city generator.

Bare-Metal STM32: From Power-Up To Hello World

November 17, 2020 by 59 Comments

Some may ask why you’d want to program a Cortex-M microcontroller like the STM32 series using nothing but the ARM toolchain and the ST Microelectronics-provided datasheet and reference manual. If your first response to that question wasn’t a panicked dive towards the nearest emergency exit, then it might be that that question has piqued your interest. Why, indeed?

Definitely, one could use any of the existing frameworks to program an STM32 MCU, whether the ST HAL framework, plain CMSIS, or even something more Arduino-flavored. Yet where is the fun in that, when at the end of the day one is still fully dependent on that framework’s documentation and its developers? More succinctly, if the contents of the STM32 reference manuals still look like so much gibberish, does one really understand the platform?

Let’s take a look at how bare-metal STM32 programming works, and make the most basic example run, shall we? Continue reading “Bare-Metal STM32: From Power-Up To Hello World” →

FreeCAD Debugging

November 16, 2020 by 20 Comments

Powerful software programs often have macro programming languages that you can use, and if you know how to program, you probably appreciate them. However, sometimes the program’s built-in debugging facilities are lacking or even nonexistent If it were just the language, that wouldn’t be such a problem, but you can’t just grab a, for example, VBA macro from Microsoft Word and run it in a normal Basic interpreter. Your program will depend on all sorts of facilities provided by Word and its supporting libraries. [CrazyRobMiles] was frustrated with trying to debug Python running inside FreeCAD, so he decided to do something about it.

[Rob’s] simple library, FakeFreeCad, gives enough support that you can run a FreeCAD script in your normal Python development environment. It only provides a rude view of what you are drawing, but it lets you explore the flow of the macro, examine variables, and more.

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Youtube-dl Makes Their Case, Returns To GitHub

November 16, 2020 by 47 Comments

Last month, the GitHub repository for the popular program youtube-dl was taken down in response to a DMCA takedown notice filed by the Recording Industry Association of America (RIAA). The crux of the RIAA complaint was that the tool could be used to download local copies of music streamed from various platforms, a claim they said was supported by the fact that several copyrighted music files were listed as unit tests in the repository.

While many believed this to be an egregious misrepresentation of what the powerful Python program was really used for, the RIAA’s argument was not completely without merit. As such, GitHub was forced to comply with the DMCA takedown until the situation could be clarified. Today we’re happy to report that has happened, and the youtube-dl repository has officially been reinstated.

Represented by the Electronic Frontier Foundation, the current maintainers of youtube-dl made their case to GitHub’s DMCA agent in a letter this afternoon which explained how the tool worked and directly addressed the issue of copyrighted videos being used as test cases in the source code. They maintain that their program does not circumvent any DRM, and that the exchange between the client and server is the same as it would be if the user had viewed the resource with a web browser. Further, they believe that downloading a few seconds worth of copyrighted material for the purpose of testing the software’s functionality is covered under fair use. Even still, they’ve decided to remove all references to the songs in question to avoid any hint at impropriety.

Having worked closely with the youtube-dl developers during this period, GitHub released their own statement to coincide with the EFF letter. They explained that the nature of the RIAA’s original complaint forced their hand, but that they never believed taking down the repository was the right decision. Specifically, they point out the myriad of legitimate reasons that users might want to maintain local copies of streamed media. While GitHub says they are glad that this situation was resolved quickly, they’ll be making several changes to their internal review process to help prevent further frivolous takedowns. Specifically the company says they will work with technical and legal experts to review the source code in question before escalating any further, and that if there’s any ambiguity as to the validity of the claim, they’ll side with the developers.

The Internet was quick to defend youtube-dl after the takedown, and we’re happy to see that GitHub made good on their promises to work with the developers to quickly get the repository back online. While the nature of open source code meant that the community was never in any real danger of losing this important tool, it’s in everyone’s best interest that development of the project can continue in the open.

Procedurally Generated Retrocomputer Emulators

November 6, 2020 by 4 Comments

[Marquis de Geek] has a profound love of old systems. Tired of writing new emulators from scratch for each project, his newest project EMF generates the emulator for him. An XML document describes the layout of the memory, CPU description, and screen handler. The output is currently a single-page Javascript emulator application with an assembly and a dissembler. However, but that backend can easily be swapped to another language such as Rust or C++.

Since EMF is a framework that provides a common way to describe the emulated machine, you get a common emulator user interface for free. There’s a lot of flexibility offered here as well. Opcodes can be implemented as a large switch statement or individual functions, depending on the target language’s performance. Self-modifying code can be detected and handled separately. Custom features or hardware can be injected easily by writing a module in the target language.

While the source code for the EMF hasn’t been released yet, several of the machines that [Marquis de Geek] has built with EMF are open-source on GitHub. So far the list includes Dragon32, Sinclair ZX80, Sinclair ZX81, Sinclair ZX Spectrum, Elliott 903, Chip8, Cosmac VIP, and the MegaProcessor. Each has a live emulator that runs in your browser.

While [Marquis de Geek] hopes to release a binary version of the EMF soon, we’re very much looking forward to the EMF source coming out once the code has been cleaned up. We love the trend towards creating easier and more accessible emulators, such as this Twitter bot that runs Atari programs.

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Local And Remote Debugging With GDB

November 6, 2020 by 27 Comments

As a debugger, GDB is a veritable Swiss Army knife. And just like exploring all of the non-obvious uses of a those knives, your initial response to the scope of GDB’s feature set is likely to be one of bewilderment, subsequent confusion, and occasional laughter. This is an understandable reaction in the case of the Swiss Army knife as one is unlikely to be in the midst of an army campaign or trapped in the wilderness. Similarly, it takes a tricky debugging session to really learn to appreciate GDB’s feature set.

If you have already used GDB to debug some code, it was likely wrapped in the comfort blanket of an IDE. This is of course one way to use GDB, but limits the available features to what the IDE exposes. Fortunately, the command line interface (CLI) of GDB has no such limitations. Learning the CLI GDB commands also has the advantage that one can perform that critical remote debug session even in the field via an SSH session over the 9600 baud satellite modem inside your Swiss Army knife, Cyber Edition.

Have I carried this analogy too far? Probably. But learning the full potential of GDB is well worth your time so today, let’s dive in to sharpen our digital toolsets.

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DIY Regular Expressions

October 29, 2020 by 12 Comments

In the Star Wars universe, not everyone uses a lightsaber, and those who do wield them had to build them themselves. There’s something to be said about that strategy. Building a car or a radio is a great way to learn how those things work. That’s what [Low Level JavaScript] points out about regular expressions. Sure, a lot of people think they are scary. So why not write your own regular expression parser and engine? Get that under your belt and you’ll probably never fear another regular expression.

Of course, most of us probably won’t do it ourselves, but you can still watch the process in the video below. The code is surprisingly short, but don’t expect all the bells and whistles you might find in Python or even Perl.

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