Al Green
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Random stuff I'm doing, in chronological order.
2024 -- 2023 -- 2022 -- 2021 -- 2020 -- 2019 -- 2018 -- 2017 -- 2016

17 April 2024: Average Conditions

Run of the mill

Real Programming chapter 11 discusses, among other things, a nifty way to calculate the average of an area of pixels using ARM NEON. While it does work, there is room for improvement: The mask setup is more complicated than necessary and it will overflow if you feed it a 1920x1080 picture with all pixels 0xff.

As before, the left and right sides are always evaluated outside the main inner loop. The mask calculation has been cleaned up and commented. 16 pixels will be shifted to the right block if possible, eliminating the inner loop if the area is small. The outer sums now handle 1920x1080 properly. Redo the inner sums yourself for larger images; it shouldn't be hard on ARMv8 with 32 NEON registers.

New version: average_neon_2024.c

Old version: average_neon_2014.c

8 April 2024: More Fun With Amps!

Elekit TU-H82 with Bugle Boy 12AU7

As mentioned 30 August 2023, Sjur and I tinker with tube gear when we get a chance. The circuits are easy to understand and tubes usually sound great. This time, I managed to assemble a Elekit TU-H82 hybrid tube amp [] all by myself. It wasn't that hard; no soldering required. Hooked it up to the Benchmark DAC with no issues. The tube is a spare Amperex Bugle Boy 12AU7 from the ever-growing pile of slightly used tubes. (And yeah, the wiring is more expensive than amp and tube combined. You use what you have.)

4 March 2024: Warriors of the Wasteland and waste copious amounts of energy

The loudest mouths have the loudest websites! As shown in this news entry, and were quick to write off efficient programming. Turns out they practice what they preach: Waste copious amounts of energy. provided these intriguing results: Oh no! This web page achieves a carbon rating of F Oh no! This web page achieves a carbon rating of F Hurrah! This web page achieves a carbon rating of A+

I couldn't care less about carbon rating, but I do care about keeping energy waste to a minimum. Further down on the result pages, the actual energy usage numbers turn up. However, the results are based on 10000 visitors per month. Top notch websites have significantly more. For websites like and, on the other hand, all bets are off. My crystal ball tells me that has about 60000 and maybe 25000 visitors per month: 2367 kWh. That’s enough electricity to drive an electric car 15151 km. 607 kWh. That’s enough electricity to drive an electric car 3887 km. 0 kWh. That’s enough electricity to drive an electric car 0 km.

This begs the question: How trustworthy are palantirs? I'll ask it. Oh, wait... Anyway, the editors of those sites can send me their visitor numbers if they want the results to be more embarrassingly correct. Don't forget that the circumference of the Earth is 40075 km.

What's the conclusion? I guess publishing pays off really well, like banking (and probably idioting). The rapidly increasing energy bills should pose no problem for them, either. Let me know if the situation changes. Meanwhile, my investments in coal power plants are paying off.

29 February 2024: Xmas Demo 2023 Secrets

Top Secret

The cat's out of the bag! After a long wait, we finally reached the (constantly revised) viewer goal for our latest demo. As promised, here's a writeup about The Xmas Demo 2023 Secrets.

9 February 2024: Real Programming Anniversary Awards

Real Programming

The Norwegian version of Real Programming was released 3 years ago today. Last year we published a 10 page summary that triggered a series of completely hilarious articles in the Norwegian digital press. While we pat ourselves on the back and drink expensive champagne cheap wine, we virtually hand out virtual awards to the two best ones:

"Dig Your Own Hole" award

Article: Håper du har plass [] - Click here for English translation

In our opinion, Torgeir Waterhouse and his posse are good at reading only headlines and nothing more. As far as we can tell, their article is a confusing mess about something. It doesn't seem to be about the book at all. In spite of that, we do enjoy the made-up quotes that don't have any connection to anything we have written. A message to the herd of authors: Let us know if you ever read the book, not just the headlines! We have prepared a couple of control questions. Anyway, we congratulate the Waterhouse crew on winning the "Dig Your Own Hole" award!

(It should be noted that Mr Waterhouse is sometimes referred to as a "technology expert" in the press, though we're not sure why.)

"Diesel Power" award

Article: De prater som det var en livsstil eller religion [] - Click here for English translation

We think that director of technology Nikolai Rygh in Norway's largest bank, DnB, presents a disturbing lack of understanding about how open-source licensing works. Among other things. We tried to figure out how he managed to include a paragraph about punch cards into the heap of words... and failed. There is one thing that is blatantly obvious to us: He is a staunch supporter of energy waste through inefficient programming. According to the financial press, DnB had record profits in 2023. That's good news: The rapidly increasing energy bills should pose no problem. Let us know if the situation changes. We congratulate Mr Rygh on winning the "Diesel Power" award!

18 January 2024: Recommended article about the Spectrum 128

ZX Spectrum 128

My first computer was a Sinclair ZX81. Turns out Rupert Goodwins over at El Reg was one of the pioneers behind the ZX Spectrum 128 and has written an article about it: The New ROM Antics - building the ZX Spectrum 128 []

The footnote is spot on. All the cool kids know this:

I also learned that writing system software for a paged memory map and no MMU is as much fun as root canal work via nostril. Don't ask.

6 January 2024: Xmas Demo Secrets

Hidden Logo

Added a Secrets section to the Xmas Demos that have them. Questions were asked about the 2020 version. They're now answered.

2 January 2024: Edgehog video update

Click to watch video on YouTube

Re-encoded the Edgehog video on YouTube in true 60 fps. Dunno what happened to it. Probably an issue with the reasonably priced USB video recorder. Might look into it, in case more live recordings are needed.

Update: The USB recorder dumps a raw H.264 stream, as expected. The software used to record and generate the original video is total crapola. Replacing the software asap. Might be snakes involved.

1 January 2024: Happy new year!

Click to watch video on YouTube

Happy new year! It's been a fun 2023 that ended with the launch of the Xmas Demo 2023. Slightly more polished than usual, and with source code that should compile on multiple platforms again. We're pretty happy with it.

We released a 10 page summary of our wildly popular book in February. This led to some press coverage in Norway. It was hilarious then; it's hilarious now. Google-translated versions of some of the articles are available on the page for your amusement.

I finally got around to tying up some loose ends from the book with the articles A Fast Image Scaler for ARM Neon in May and Edgehog in June. Is it fast? Yes. Is it readable? Yes. Is it C and intrinsics? Duh.

Stay tuned for more awesomely great stuff in 2024! (May be considered regular stuff in some regions)

Article Licensing Information

This article is published under the following license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0)
Short summary: You may copy and redistribute the material in any medium or format for any purpose, even commercially. You must give appropriate credit, provide a link to the license, and indicate if changes were made. If you remix, transform, or build upon the material, you may not distribute the modified material.

Licensed Items

Item: Poorly made parodies of the and logos. "Artist": Me.
Item: Coal Power Plant. Artist: Adrem68. License: Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
Item: ZX Spectrum 128. Artist: Bill Bertram. License: Attribution-Share Alike 2.5 Generic (CC BY-SA 2.5)
Item: Newspaper from Paperboy (1986 C64 game). License: Screenshot via MobyGames

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