Part two of Make in Prolog. This is extending the make implementation with using hashes of inputs instead of modification time for out-of-date detection.

Path Patterns

But first, a discussion on matching on paths. In the previous implementation I used a representation of paths that has some flags in it. Let me show the pathology by studying a few simple paths.

1. The simplest is main.cpp, which doesn’t work in the build system because we use the pattern Dirs/File so you have to use '.'/main.cpp.
2. The path_segments_atom translates into a left-associative (a/b)/c which is contrary to expectations and actual the filesystem hierarchy. (Which is a/(b/c) to be clear). This makes matching on filenames easy but makes adding a root directory (or checking the root directory) inconvenient.

The first issue is going away here as we will put the sources into the src directory (and use build for build files).

This turned out to be a long post, so here is an outline.

Make in Prolog code at https://git.kovirobi.uk/kovirobi/prolog-make.

I have maintained for a long time that Prolog and Makefiles are very similar, recently I spent some time showing this is so. Let’s explore this. The similarity comes from the way they both operate, looking at a database of facts, trying to prove what the user asked.

Parts: 1, 2

Time to start using the C library! Though this article is about all the things that can go wrong when you start to do that. First, let’s replace the infinite loop at the end of init.S with a jump to the C library’s entry point (in this case newlib).

init.S

@@ -21,19 +28,38 @@ _entry:
     stmia   r9!, {r0-r7}
     b       1b
 2:

-1:  b       1b
+    b _mainCRTStartup

The first issue is:

Parts: 1, 2

Recently I was building the platform support for a Cortex-R5 microcontroller. It is executing out of QSPI flash, with SRAM (static RAM, doesn’t need a controller set up unlike DRAM) and tightly coupled memory: ATCM is typically for instructions, and BTCM is typically for data. The benefit of {A,B}TCM is much faster access, and it is present even when doing erases/writes to the flash. On the other hand, it is not accessible for other devices in the system (e.g. network DMA engines), unlike the SRAM.

I now have an additional¹ name, “Archaea” (like the domain of life). It’s a pun on the initials RK, how fabulous! Besides, Archaea are cool, living in extreme environments like high salt concentrations or sulphur vents. Like London².

I wished my friend Michael happy birthday, since he enjoys the odd puzzle, I did it in rot13 (an old internet/usenet tradition, to hide spoilers).

The phrase “Happy Birthday Michael” is “Unccl Oveguqnl Zvpunry” in rot13, and granted it does look like it could be an Eastern European language, so he plugged it into Google Translate, which apparently¹ did the following:

(Safe, just trying to get to the bottom of my struggles with the weekend.)

Often in therapy, I am asked what help do I need, what would help life be better. My usual answer is I would like to enjoy life, but so far nothing I have found helps with that. But there is some structure to my struggles, often on weekdays I manage to get by, or at least not think about my depression. There is work which makes me feel like I have accomplished something, and the things I find easy (programming) come in useful. And of course, I have managers who try to keep me on track and doing work.

This is just a heads up, fresh installs of Docker 29.0 will break flows relying on pinning containers by hash.

ⓘ Note

Docker Engine 29.0 and later uses the containerd image store by default for fresh installations. The containerd image store uses snapshotters instead of the classic storage drivers described on this page. If you’re running a fresh installation of Docker Engine 29.0 or later, or if you’ve migrated to the containerd image store, this page provides background on how image layers work but the implementation details differ. For information about the containerd image store, see containerd image store.

(I should say I’m safe, just lonely.)

No idea for whom, what or even why. Maybe for someone to feel less alone. But for me oestrogen has helped be less depressed on average. Not this week. It has been a lot, without anything specific being much. Work went okay, if I were to recall other things besides work I’m sure they went okay too.

But I felt unable to connect to others or even myself, which is a big ongoing problem for me. I have tried a lot of what life has on offer and it seems like programming is the only thing marginally enjoyable, but sometimes I get tired and burnt out from it.

There is an excellent tool called entr that can be used to run commands on file change. I always forget what it’s called, so I’ve put this tip here. (N.b.: it stands for Event Notify Test Runner.)

It can be used to automatically re-compile (and even restart servers) while you are editing the source files. A simple example is

git ls-files | entr make

Which works well for repos which only track source files. And depending on what is in your makefile, it can for example build and flash the embedded program onto the embedded target. (I tend to use CMake for projects, with a simple makefile to avoid setting long makeprg/makecmd, so I can just do :make<ret>.)