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Diary, April 2024

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Friday, April 5, 2024

Trying revng again

Recently, the decompiler has gone open source (announcement). On January 16, I reported about trying it. I encountered a bug that I did report as issue #345. In the past days, I did some debugging myself with respect to this issue and even made some suggestions about the cause. I also studied part of the code base. Today, the issue was fixed, but when I looked at the commit. with the fix, I realized that it was something that I would have been able to find myself, not having some knowledge about the development of the code. It looks like at some point a change was made where one of the uses had not been updated yet. Now the command that I used in january did work and resulted in a large file cc_x86.translated. It looks like a binary file. I studied the documentation, but I failed to figure out how to decompile the binary. Maybe the documentation is out-dated. I did enlist for the closed beta for the UI, I presume, from which the revng back-end is called.

Saturday, April 6, 2024

25.3° Celsius

The temperature at Twenthe Airport has gone up to 25.3° Celsius, which breaks the previous record of 23.3° on this date in 2020. This means we have the first regional summer day, which is defined as the temperature getting above 25°C. Yesterday, the maximum temperature was 17.0°C and the prediction for tomorrow is 18.6°C. This warm day is caused by Storm Kathleen, which pushes a lot of warm air from the South as can be seen on this Animation on instagram by Scott Duncan. We cleaned the bench outside and spend some time reading there. In out North facing garden, I saw the temperature go up to 27.c°C on a digital thermometer. I have no idea how accurate it is, but I do know that in the city it is often a bit warmer than in the open field.

Trying revng more

From someone on the Discord 'orchestra' channel I got some help explaining what commands to use. I used the following command on the cc_x86 executable with a size of 14.2Kbyte, which is produced during the execution of the live-bootstrap from the file cc_x86.M1:
revng artifact --analyze decompile-to-single-file cc_x86 | revng ptml >cc_x86.c
This produces a cc_x86.c file of 20Mbyte file with 1530 switch-statements with a total of 52200 cases. It also has 9863 variable declarations and a large number (17889 or more) of assignment statement where one of the variables is simply assigned to another (possibly with a cast). Not something that is very useful for understanding the binary. I guess that the the decompiler has problems with the non-standard calling convention that you do find in binaries created with hand coded assembly.

Rocannon's World

Today, I finished reading the book Rocannon's World by Ursula K. Le Guin, which is the first book in the omnibus Worlds of Exile and Illusion and which I started reading on December 2 last year. The main part of the story covers a long and sometimes dangerous journey over the surface of a planet, much like the one found in The Left hand of Darkness. Honestly, I find this way of telling a story, with a single story line, a bit boring, especially when it is only in the last chapters and epilog somethings are suggested that place the whole story in a different light. Spoiler: Did I understand it correctly that it was totally not accidental that Rocannon met the Ancient One and that entity was the 'shadow' that he had sensed before?

Tuesday, April 9, 2024


Early in the evening, Conny and I arrived in Rotterdam and checked-in at the Art Hotel. A bit later than we had planned due to some stupidity of mine. We crossed a street to find some place to eat. The Amaana restaurant was closed due to Eid al-Fitr. Around the corner we found Eethuis Nakiş, a Turkish restaurant, where we ordered Kapsalon with chicken. From there we walked to Erasmusbrug (English: "Erasmus Bridge") where we took some pictures. One of the pictures Conny took, is shown below:

Wednesday, April 10, 2024


We left the hotel a little after ten in the morning and took the metro to the metro station Leuvehanven. From there we walked along the Nieuwe Maas. We saw the moter yaught Sherakhan. We arrived at the pedestrian and cyclist entry of the Maastunnel and used the wooden escalators to get to pedestrian tunnenl. We walked into the tunnel until where it gets level. This is about 20m below sealevel. I remember having visited this tunnel as a child. Probably just before the summer holidays of 1967. Interesting to visit it again after almost 57 years.

From there we walked to Depot Museum Boijmans Van Beuningen through the park where we saw the artwork Lost Pearl by Madeleine Berkhemer. Before going inside, we took some pictures of ourselves in the reflective plating on the outside. I found the following art works noteworthy:

We went to the roof-top and looked over the city.

Form the depot, we went to Het Nieuwe Instituut to see the exhibition REBOOT: Pioneering Digital Art. I found the following works noteworthy:

I walked around the book store on the ground floor and at 14:16:27, I bought the Great Trees of New York Map for € 10.80.

We took the metro to Delfshaven, now a borough of Rotterdam. While walken there, we past the shawarma store "El Aviva" where the Kapsalon dish was first prepared. We walked through the area where the original city Delfshaven started as the harbour for Delft. From there we walked to city center along the road called Nieuwe Binnenweg. At number 146, I noted a space invaders tile, which is on the website of Invader for Rotterdam. Conny knows this road from the time she worked in the neighbourhood. We briefly visited the bookshops Van Gennep and Donner. In between the visits we had some icecream at McDonalds. We had dinner at Urumqi restaurant, an Uygur restaurant. Conny had a (rather spicy) noddles dish and I had the Urumqi polo dish, which tasted just like I remembered from having it before.

Thursday, April 11, 2024

Rondom PS

Conny and I visited Peter Struycken and together with him, we went to see the exhibtion Rondom PS: Peter Struycken en bevriende werken (in English: 'Around PS: Peter Struycken and befriended works') at Gorcums Museum. We both enjoyed this exhibition very much. It gives a good overview of his works. I do like the newest incarnation of his SHFT 34 work, now in the form of a mini computer in a wooden frame of which there were two on display. Besides the works by Peter Struycken, I found the following works noteworthy:

Afterwards, we also brought a short visit to the exhibition Rondom 3D with works by:

Friday, April 12, 2024

Planet of Exile

I finished reading the book Planet of Exile by Ursula K. Le Guin, which is the second book in the omnibus Worlds of Exile and Illusion and which I started reading on April 6. I found this book a bit more exiting than the first book. I felt that it ended quite abruptly.

Saturday, April 13, 2024

In to the city

At Fotogalerie Objektief I saw the exhibition WOW, a World of Wildlife with photograpsh by Edgard Berben. At Concordia, I saw the exhibition by Roland Farkas.

Tuesday, April 16, 2024

Hare Krishna Tree

When I opened the Great Trees of New York Map, which I bought last Wednesday, I found a mentioning of the Hara Krishna Tree. I found descrition of these on the Atlas Obscura and the Official Website of the New York City Department of Parks & Recreation websites. The latter mentions that it was on October 9, 1966, that Prabhupada and his followers sat beneath this tree and held the first outdoor chanting session outside of India. They very probably also chanted the famous Hara Krishna mantra. One of the people present was Allen Ginsberg. For the International Society for Krishna Consciousness the chanting session is seen as the start and the movement. When I was a teenager, I encountered Hara Krishna followers on the Dam in Amsterdam. I felt a little bit attracted to that life style at the time being. In 2016 and 2017 when I joined some mantra singing sessions, I also sang the Hara Krishna mantra, but a bit more melodic than in most of the videos that there are on YouTube. One that comes a bit close is this one.

Straight skeleton

In the past month, I worked on implementing an algorithm for constructing the straight skeleton of an area defined by polygons (with holes). I really struggled with implementing this and tried several approaches. I did consider a sweep algorithm were edeges are added one by one using doubly connected edge list, but that required a lot of modifications. So, I ended up looking at a method of constructing the area adjecent to a given edge making use of all the edges that are visible from this edge based on the triangulation code I wrote last year January. That approach took me longer than expected. And even now it looks like it is not flawless and needs more work for some edge cases. At least, I feel confident to present it. See this page for the demo. I probably will continue working on that page after this post, fixing bugs, cleaning up the code, and present the underlying code in a readable manner. I have no idea of my code matches any of the other implementations.

Wednesday, April 17, 2024


At 10:21:04, I bought the book Quadrivium: rekenkunde, meetkunde, muziek en astronomie voor iedereen written by Miranda Lundy written in Dutch, published by Librero in 2013, and translated by Cornelis van Ginneken and Ireen Niessen from Quadrivium written in English, ISBN:9789089983039, from charity shop Het Goed for € 2.00.

At 14:44, we received the book Historische wegenatlas NL: Nederland in beweging written by Martin Berendse and P. Brood in Dutch and published by Uitgeverij WBooks in 2024, ISBN:9789462586116, which we bought yesterday online for € 39.95.

Friday, April 19, 2024

City of Illusions

I finished reading the book City of Illusions by Ursula K. Le Guin, which is the second book in the omnibus Worlds of Exile and Illusion and which I started reading on April 12. I felt that the middle part of the book was rather boring. Le Guin seems to have a preferance for writing about characters traveling through cold and hostile landscapes. This is the third novel I read where this takes a sizable part of the story. Then end however was a real page turner. Again the story ends quite abruptly. Not very satisfying. An interesting read anyhow.

Sunday, April 21, 2024

Dune Tarot

In the Children of Dune mini-serie there is a scene where Princess Irulan visits Gaius Helen Mohiam who is inside a cage, where she seen laying down hexagonal tiles. You can hear a kind of metalic sound when she lays down the tiles, suggesting that the tiles are made of a solid material. The scene is based on the sixth chapter (not counting the intro chapter) of Dune Messiah. There it describes that she 'had been spread a deck of the new Dune Tarot cards.' At the end of the chapter she returned to her tarot cards, getting the Kwisatz Haderach of the Major Arcana and Eight of Ships thinking: 'the sibyl hoodwinked and betrayed'. These seem to matched with the The World and the Eight of Cups cards of the current day tarot. In Dune Messiah it is said that so many people using the Dune Tarot muddled with prescience.

Some weeks ago, someone posted three images that are watermarked with the text The Prop Shop of London. (Searches for that name link to So, it seems that the tiles were sold at one point. I wrote an image manipulation program for the MySample editor to extract the tiles and combine them into a single image, which is show below:

I spend some trying to match the different tiles with the tarot. The last two rows match with the Suit of swords and Suit of goblets. The symbols near the top of the tiles, seems to be numbers. For the top row, it is not clear to me whether these belong to Major Arcade or the Suit of coins. This taking into account, I would come up with the following matchings:

It is possible that this tile set consisted of more tiles than the one shown here. In a shot of the scene, two 'Ace of Cups' tiles are visible. Implying that there were several tiles of the same design used. All tiles can be seen layed in the same orientation, whereas in tarot the orientation can play a role where an upside-down card is given a different interpretation. An hexagon tile can have a total of six orentations.

In the last months there has been a flood of first time reaction videos:

Tuesday, April 23, 2024

Emulator: Important milestone

I spend some time looking at the i386 Eumlator I have developing to verify the live-bootstrap project. In the past months, I did look at revng for finding the bug. This afternoon, I found the bugs. One was related to me excluding the O_EXCL from the call of the open function. The other was a bug in the emulation of the waitpid function with respect to the wstatus argument that was ignored. If this argument is not NULL, the status should be stored in the int to which it points. The solution can be found in commit 2914a15d. I pulled the commit 0e6133ee from live-bootstrap and verified that it returned the same result for stage0. Maybe I will first match the memory layout of the emulator with the one that Linux uses as I figured out on March 24. I am also thinking some ways to improve the performance a bit.

Friday, April 26, 2024


At 15:56:36, I bought the following two books from charity shop Het Goed:

This months interesting links

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