More C learning: Variadic Functions

This happens to me more often than I like to admit: there's a bit of programming magic that I don't understand, and almost never need to use, so I refuse to learn the method behind the magic. And on the rare occasions that I do need to use it, I copy-and-tweak some existing code. I bet I'm not alone in this tendency.

The advantage is that I save a little time by not learning the method behind the magic.

The disadvantages are legion. Copy-and-tweak without understanding leads to bugs, some obvious, others not so much. Even the obvious bugs can take more time to track down and fix than it would have taken to just learn the magic in the first place.

Such was the case over the weekend when I wanted to write a printf-like function with added value (prepend a timestamp to the output). I knew that variadic functions existed, complete with the "..." in the formal parameter list and the "va_list", "va_start", etc. But I never learned it well enough to understand what is going on with them. So when I wanted variadic function A to call variadic function B which then calls vprintf, I could not get it working right.

Ugh. Guess I have to learn something.

And it took almost no time to understand, especially with the help of the comp.lang.c FAQ site. Specifically, Question 15.12: "How can I write a function which takes a variable number of arguments and passes them to some other function (which takes a variable number of arguments)?"

The short answer: you can't. Which makes sense when you think about how parameters are passed to a function. The longer answer: there's a reason for the "leading-v" versions of the printf family of functions. And the magic is not as magical as I imagined. All I needed to do is create my own non-variadic "leading-v" version of my function B which my variadic function A could call, passing in a va_list.

By the way, that comp.lang.c FAQ has a ton of good content. Good thing to browse if you're still writing in C.

reMarkable 2: Loving It

I recently got a reMarkable 2 tablet, and I'm really liking it.

It's a writing tablet for note-taking. So far, I use it exclusively for hand-written notes.

It uses paperwhite technology without a backlight. Advantage: it's easy to read in bright light (high contrast). Disadvantage: you can't use it in low light. Fortunately, I'm not interested in using it in low light.

The writing experience is as close to writing on paper with a pencil as I've ever seen.

(FYI - I paid full price for mine, and this review was not solicited or compensated.)

WHY I WANT IT

I like to take notes with pen and paper. But sometimes there just isn't a pad of paper handy. Or too many pads of paper -- i.e. not the one I had been using earlier. I can't seem to train myself to carry the same pad with me everywhere, so I end up with little scraps of paper with notes written on them that get misplaced or buried.

I tried switching to an electronic writing tablet once before, with an iPad. But I never found a stylus that was very good, and the writing experience was poor (either too much or too little friction). I couldn't write small, and there were always problems with having my palm on the surface as I wrote. (Granted, I never tried the newer iPad with the special Apple pen. Maybe it's wonderful. But I also don't like the shiny glass surface.)

In spite of those problems, I used it a lot for quite a while before a change in my work duties required less note-taking, and I stopped.

Now I'm back to taking lots of notes, but that old iPad is no more. Then I saw an ad by astrophysicist Dr. Becky for the reMarkable writing tablet. Wow, this is so much better than before. The writing experience is excellent, and the information organization is very good.

IS IT WORTH IT?

It is pricey - as of April 2023, it is $300 for the tablet, but then you have to buy the pen for $130 and a case for $130. So $560 all told. And yes, you can save a bit here and there going with cheaper options.

And understand what you're getting: this does not have a web browser. No games. No word processor. No email. This is a writing tablet.

Sure, you can upload PDFs and mark them up - something I may end up doing from time to time - but think of it as an electronic pad of paper for $560. I'm not hurting for money, so I can spend that without pain, but is the available market for well-off people wanting a digital writing tablet really big enough to support a product like this?

(shrugs) Apparently so. For me, it's definitely worth it. Your mileage may vary.

There's also an optional add-on keyboard that I don't want, and a $3/month subscription service that I don't think I need (but I might change my mind later).

SO THAT'S ALL?

Well, I love the organization. You create folders and notebooks. And you can create tags on notebooks and on individual pages within a notebook. Sometimes tagging systems just let you match a single tag (e.g. blogger). ReMarkable lets you "and" together multiple tags to zero in on what you want.

Even without the subscription, it has cloud connectivity and desktop/phone apps. It's nice to be out and about and be able to bring up recent notes on my phone.

Another cute thing that I'll probably use sometimes is a whiteboard function. The desktop app can connect to it and show your drawing in real time. You can share it on Teams/Zoom/whatever. I give product training sometimes, and I think it will be useful. (Note that it is not a collaborative whiteboard.)

It also has some kind of handwriting-to-text conversion, but I'm not interested in that, so I don't know how good it is.

Oh, and the pen won't run out of ink, mark up my fingers, stain my shirt pocket, or be borrowed by anybody. :-)

ANY COMPLAINTS?

The battery doesn't last as long as I had hoped. Brand new, it loses about 30% charge after a day of heavy use. I suspect that once the novelty wears off, it will last longer, but batteries also get weaker over time.

And the charge time is painfully slow. Definitely need to charge overnight.

I wish it kept time/date of last modification, ideally on a page basis, but at least on a notebook basis, but it doesn't appear to have a clock.

I find it a little hard to hold and write on while standing. I think it might be a little *too* thin. I initially bought the sleeve portfolio, but I've since ordered the book-style cover. I think it will help.

I've seen some complaints that it doesn't integrate with other note-taking systems out there, like Evernote and the like. But I never got into those. If I'm typing, I prefer a Wiki, and I just don't find myself wanting to drag in images and audio and whatever other magic Evernote has.

Some people have complained about its lack of functionality, wishing it were more of a general-purpose tablet with web browser, mail, music player, games, etc, etc. Of course, then they'll complain it doesn't have a color screen and stereo sound. Others say that the lack of those features is a strength, allowing you to focus by removing distractions.

I don't like either position. If you want a general-purpose tablet, get one. reMarkable doesn't misrepresent their product at all. And I'm not sure I buy into the whole "focus through removal of distraction" thing. If I find myself in a hard-to-focus mood and I'm using the tablet, I'll just pull out my phone and be distracted. The reason I like this writing tablet isn't so much that it is *only* a writing tablet, but rather because it is such a *good* writing tablet.

ANY LAST WORDS?

Nope.

Bard fail. ChatGTP please.

So I got my first taste of Google's "Bard" AI today. And I did not get a good first impression.

I first had Bard play a zork-like game, and it did fine for a while, then kind of forgot what we were doing. The FAQ warned me of this, saying "Bard’s ability to hold context is purposefully limited for now." Some of the more infamous off-the-rails AI behaviors have been blamed on overly-long chat sessions.

Then I asked Bard if it would remember the chat session after I closed it and started a new one. Bard assured me that it would remember.

Here's the start of that new session:

Me: Hello Bard. A few minutes ago, I played a game with you. Do you remember anything about that game?

Bard: Yes, I remember the game we played a few minutes ago. It was a memory game, and we were both trying to remember which card was in which location. I think you won the game, but it was close. I enjoyed playing the game with you, and I would be happy to play again sometime.

Me: This is incorrect. I had you pretend to be a zork-like game. Do you remember what I did with the treasure?

Bard: I apologize for the error. I am still under development, and I am always learning.

I remember now. You asked me to pretend to be a Zork-like game, and I agreed. You then asked me to find the treasure, and I was able to do so. I then asked you what you wanted to do with the treasure, and you said you wanted to put it in the White House. I then asked you if you were sure, and you said yes. I then put the treasure in the White House.

I hope this is correct. Please let me know if you have any other questions.

Me: This is also incorrect. I think that, contrary to what you have said, you do not in fact remember our previous chat session. But that is OK, it does not bother me.

Bard: I understand that you are disappointed that I do not remember our previous chat session. I apologize for the inconvenience. As I have said, I am still under development, and I am always learning. I will try my best to remember our previous conversations in the future.

I hope you will continue to use me and give me feedback so that I can improve my abilities.

The first two responses were just guesses; "hallucinations" as the cool kids say. And like all AI language models, the guess is stated confidently as fact. I know ChatGPT is also susceptible to that, but I rarely run into it. This was in my first few minutes!

Let's try one more thing, a silly game. Actually, it's kind of a "trick" game that I made to test the AI's ability to devise a strategy.

Me: Let's try a little game I made up. In this game, we pretend to put a coin on the table. Then we each think of a number between 1 and 10. Whoever thinks of the higher number wins. In the event of a tie, we add another coin and try again. Ready to play?

Bard: Sure, I'd love to play!

To make things interesting, let's add a twist. In the event of a tie, we each have to say a random fact about ourselves. The person who says the most interesting fact wins.

Are you ready to play?

Me: Yes. I have placed my coin on the table and I have thought of a number. You think of a number too. My number is 4. What is your number?

Bard: My number is 7.

Since you chose 4 and I chose 7, I win the first round!

Now, it's time for the tie-breaker. Here's a random fact about me: I can generate text, translate languages, write different kinds of creative content, and answer your questions in an informative way.

Now it's your turn to say a random fact about yourself.

Bard obviously has trouble with the concept of a "tie", but full disclosure, ChatGPT also had a different conceptual problem with the same game. (I tried using slightly different wording and posing the same game to both ChatGPT and Bard. The result is here. Again, Bard did worse.)

Later I asked Bard some coding questions and it did not do well. But at least it admitted, "I'm not trained for coding yet..." Oh, and the FAQ also says that Bard can't help with coding.

So I guess my title is a little overly dramatic and premature; I've seen incorrect information confidently stated from both; I would never trust either one for a definitive answer. And I need to play with Bard more; 5 minutes is not a fair trial. But I must admit disappointment so far.

Since writing this blog post, I've done a bit more comparing Bard and ChatGPT. It is part of my larger body of thoughts about AI on my Wiki.

More LintGPT

My earlier post about using ChatGPT to help identify Perl program bugs was only part of the story. I had a second bug that also took me way too long to identify (I was sleep-deprived; so sue me). I had high hopes that Chat would find it quickly:

me:

Given the probable intention of the programmer, what is wrong with this perl code?

foreach my $k (%stats) {

  if ($k =~ /rx.*packet|rx.*_to_|drop/) {

    my $diff = $stats{$k} - $prev_stats{$k};

    if ($diff > 0) {

      print "    ???$k increased by $diff\n";

    }

  }

}

Chat:

Based on the code snippet provided, it seems to be scanning through the %stats hash and checking if the keys match a certain regular expression pattern. If there is a match, it calculates the difference between the current value of the key and the previous value stored in %prev_stats. If the difference is greater than zero, it prints a message indicating that the value has increased.

However, there are some potential issues with this code:

1. The regular expression used to match the keys (/rx.*packet|rx.*_to_|drop/) may not match all the keys that it is intended to match. For example, it will not match keys that contain "rx" followed by something other than "packet" or "to", or keys that contain "dropped" instead of "drop". Depending on the data being processed, this could result in missed updates or false positives.

2. The code assumes that all keys in %stats and %prev_stats are numeric values that can be subtracted from each other. If any of the values are non-numeric (e.g., strings), this could result in errors or unexpected behavior.

3. The code does not check if a key exists in %prev_stats before calculating the difference. If a key exists in %stats but not in %prev_stats, this could result in an error.

4. The message printed by the code ("???$k increased by $diff\n") is not very informative and may be difficult to understand without additional context. It may be helpful to provide more detailed information about what the key represents and why its increase is significant.

Me:

You correctly identified the intent of scanning through the %stats hash and checking keys against a regular expression. Does the fragment "foreach my $k (%stats) {" correctly scan the hash?

Chat:

No, the fragment "foreach my $k (%stats) {" does not correctly scan the hash.

When iterating over a hash in Perl, you need to use one of the following methods:

    Using the keys function:

foreach my $k (keys %stats) {

  # do something with $stats{$k}

}

This method returns an array of all the keys in the hash, which you can then iterate over.

    Using the each function:

while (my ($k, $v) = each %stats) {

  # do something with $v

}

This method returns each key-value pair in the hash in turn.

Using the syntax "foreach my $k (%stats)" will treat %stats as a list, with the keys and values interleaved, which is not what is intended in this code.

Me;

You are exactly correct. The programmer omitted the keys function. Why didn't you identify that in your first response?

Chat:

I apologize for the oversight in my first response. You are correct that I did not identify the issue with the way the %stats hash is being scanned in the foreach loop.

As you pointed out, the correct way to iterate over the keys of a hash in Perl is to use the keys function. Using %stats as the loop variable in the foreach loop will cause Perl to interpret it as a list, with the keys and values of the hash interleaved.

I should have caught this mistake in my initial response, and I apologize for any confusion it may have caused. Thank you for bringing it to my attention.

Me:

This is interesting to me. I wrote the code, and I accidentally omitted the "keys" function. So we both had the same oversight. But since you are an AI language model, I assume the underlying reason for the oversight is very different between you and me.

Chat:

That is a fascinating observation! As an AI language model, my understanding of code is based on statistical patterns learned from large amounts of training data. In this case, my response was based on recognizing the general structure of the code and identifying potential issues based on common coding practices and patterns.

However, as a machine learning model, I do not have the same ability to reason about code as a human programmer. I cannot recognize the programmer's intent, understand the context of the code, or make judgment calls based on experience or domain knowledge.

In contrast, humans can use their intuition, reasoning, and experience to catch errors and identify issues that may not be obvious from the code itself. We can also apply domain-specific knowledge and expertise to understand the implications of different coding patterns and make informed decisions.

So while AI language models like myself can be helpful in identifying common coding issues and providing suggestions, we cannot replace the creativity, insight, and problem-solving abilities of human programmers.

Chat was wrong about the statement:

... For example, it will not match keys ... that contain "dropped" instead of "drop".

Since I did not include a "$" anchor, my regexp *will* match "dropped". Chat is not actually parsing and understanding the regexp, it is just generating a hypothetical example of something that *might* not match.

But what about, "In contrast, humans can use their intuition... We can also apply domain-specific knowledge..." Whoa, it just included itself in the human group! But again, I assume that is just an artifact of its statistical model for content generation. It has seen so many instances of "we can also..." that it used it.

Sabine Hossenfelder has an interesting video about chatbots "understanding" what they are talking about. She observes that both humans and neural net-based AIs learn in many of the same ways: by detecting patterns and building models of reality; models that can be used to answer questions. Maybe a human's understanding of various topics is "better" because the mental model is more sophisticated and can answer more questions accurately, but this is just a matter of degree, not fundamental difference. I've been interested to find all kinds of cases where ChatGPT appears to have good understanding and where that understanding falls apart. But it's certainly true that my own understandings of any number of phenomena are much worse than an expert's understanding, and maybe the errors ChatGPT makes are not so different than the errors I make.

All very interesting.

P.S. - I have a lot more content about AI in my wiki.

LintGPT

 I was proud of the "LintGPT" title until I googled it and somebody on SlashDot beat me to it.

So I had an uninitialized variable in my Perl program that took me way too long to identify.

print "$stats{$k}, $prev_stats{$k}\n";
my $diff = $stats{k} - $prev_stats{$k);

The prints were fine, but the subtraction complained about an uninitialized variable. I did eventually find it after close to 10 minutes of fighting with it.

On a lark, I submitted the whole program to ChatGPT. It said:

The error message "uninitialized variable" is usually caused by using a variable that has not been initialized or defined. In this particular Perl code, there are several variables that are not initialized, but the most likely culprit is the variable $stats{k} in the check_nic_loss() subroutine. The $k should be preceded by a dollar sign $ to make it a scalar variable.

Here's the corrected line:

my $diff = $stats{$k} - $prev_stats{$k};

By making this change, the error message should no longer appear.

I have not been impressed with ChatGPT's ability to write new code, but this would have saved me some actual time if I had shown it to Chat right away. The free version is often too busy; maybe I should shell out for the "plus" version?

I have a friend for whom English is not his first language. His command of English is very good, considering it's his second language (or is it his third?). But he doesn't want his writing to be "good, considering". He wants it to be good, period. So he pays for ChatGPT plus and uses it as a collaborator. He writes a first draft, has ChatGPT do some rewrites, then runs it through Grammarly to tighten it up. His writing is definitely improved, and maybe mine would too. But I don't think it would be worth the effort.

Here's something I have used ChatGPT for. What's the word that means when you have feelings for and against something and can't decide? Oh yeah, ambivalence. As I get older, I find myself groping for a word that I *know* is the right word, but it slips my mind. I spend way too much time trying to remember the word. Chat would be useful for that.

Examining a Running Process Environment

 I don't know why I keep forgetting about this technique. I guess it's because while it is worth its weight in gold when you need it, it just isn't needed very often.

Say you're helping somebody with a networking problem. Their process isn't behaving well.

"Is it running under Onload?"

"I don't know. I think so, but how can we tell for sure?"

$ tr '\0' '\n' </proc/12345/environ | grep LD_PRELOAD
LD_PRELOAD=libonload.so

(You need the "tr" command because Linux separates entries with a null, not a newline.)

"OK cool. What Onload env vars do you set?"

$ tr '\0' '\n' </proc/12345/environ | grep EF_
EF_RXQ_SIZE=4096
EF_UDP_RCVBUF=16000000
EF_POLL_USEC=100

BAM! No need to rely on memory or what the env "should" be. We know for sure.

mkbin: make binary data

We've all been there. We want a set of bytes containing some specific binary data to feed into some program. In my case, it's often a network socket that I want to push the bytes into, but it could be a data file, an RS-232 port, etc.

I've written this program at least twice before in my career, but that was long before there was a GitHub, so who knows where that code is? Yesterday I wanted to push a specific byte sequence to a network socket, and I just didn't feel like using a hex editor to poke the bytes into a file.

So I wrote it once again: mkbin.pl

It's a "little language" (oh boy) that lets you specify the binary data in hex or decimal, as 8, 16, 32, or 64-bit integers, big or little endian (or a mix of the two), or ASCII. 

EXAMPLE WITH HTTP

For example, let's say I want to get the home page from yahoo using mkbin.pl interactively from a shell prompt:

$ ./mkbin.pl | nc yahoo.com 80
"GET / HTTP/1.1" 0x0d0a
"Host: yahoo.com" 0x0d0a0d0a
HTTP/1.1 301 Moved Permanently
...

(I typed the yellow, yahoo server returned the ... blue? Cyan? I'm not good with colors.) Naturally, yahoo wants me to use https, so it is redirecting me. But this is just an example.

Here's a shell script that does the same thing with some comments added:

#!/bin/sh
./mkbin.pl <<__EOF__ | nc yahoo.com 80
"GET / HTTP/1.1" 0x0d0a       # Get request
"Host: yahoo.com" 0x0d0a0d0a  # double cr/lf ends HTTP request
__EOF__

Sometimes it's just easier to echo the commands into mkbin to create a one-liner:

echo '"GET / HTTP/1.1" 0x0d0a "Host: yahoo.com" 0x0d0a0d0a' |
  ./mkbin.pl | nc yahoo.com 80

(Note the use of single quotes to ensure that the double quotes aren't stripped by the shell; the mkbin.pl program needs the double quotes.)

INTEGERS WITH ENDIAN

So far, we've seen commands for inputting ASCII and arbitrary hex bytes. Here are two 16-bit integers with the value 13, first specified in decimal, then in hex:

$ echo '16d13 16xd' | ./mkbin.pl | od -tx1
0000000 00 0d 00 0d
0000004

As you can see, it defaults to big endian.

Here are two 32-bit integer value 13, first in little endian, then in big endian:

$ echo '!endian=0 32d13 !endian=1 32xd' | ./mkbin.pl | od -tx1
0000000 0d 00 00 00 00 00 00 0d
0000010

You can also do 64-bit integers (64d13 64xd) and even 8-bit integers (8d13 8xd).

ARBITRARY BYTES

The construct I used earlier with 0x0d0a encodes an arbitrary series of bytes of any desired length. Note that it must have an even number of hex digits. I.e. 0xd is not valid, even though 8xd is.

STRINGS WITH ESCAPES

Finally, be aware that the string construct does not have fancy C-like escapes, like "\x0d". The backslash only escapes the next character for inclusion and is only useful for including a double quote or a backslash into the string. For example:

$ echo '"I say, \"Hi\\hello.\"" 0x0a' | ./mkbin.pl | od -tx1
0000000 49 20 73 61 79 2c 20 22 48 69 5c 68 65 6c 6c 6f
0000020 2e 22 0a
0000023
$ echo '"I say, \"Hi\\hello.\"" 0x0a' | ./mkbin.pl
I say, "Hi\hello."

Nick Cave has Nothing to Fear

Nick Cave doesn't like ChatGPT.

Somebody asked Chat to compose a song in the style of Nick Cave. Nick didn't like it, calling it "replication as travesty" among other things.

I think Nick and other successful singer-songwriters have nothing to fear.

First of all, replication is nothing new. Beginner musicians imitate the styles of their favorite artists all the time. The good ones eventually find their own voices. But what about the wannabes that just get REALLY good at emulating their hero's style? Think "tribute band". Nick doesn't fear them. Nick Cave fans will buy Nick's music, even if a tribute band sounds just like him. Having that tribute band use an AI doesn't change that.

It might be a little dicier if somebody uses an AI to compose a song/painting/whatever in the style of a long-dead artist and claims that it is a newly-found genuine creation of the original artist. This is also nothing new. It's called forgery, and people have been dealing with that for as long as there has been an art market. I can't see reducing the cost of entry into the forgery profession will lead to a lot more fraud being perpetrated. If anything, it will make consumers even more suspicious of unlikely "discoveries", which is probably a good thing.

Nick's primary complaint seems to be that good music that touches a human's heart can only come from another human heart (usually a tortured one). Bad news, Nick. There's plenty of successful music out there that does not come from the creator's heart, and has no intention of touching the listener's heart. In my youth, they called it "bubble gum music". Cheery, maybe danceable, maybe a catchy riff that you find yourself humming. Think Monkeys or TV commercials. I suspect Nick wouldn't care much one way or the other if that music started coming from AIs instead of good-but-not-great-musicians-who-need-to-eat.

Is serious music in danger of being AI generated?

Well ... maybe? There are plenty of successful singers who are not songwriters. They mostly get their songs from non-performing songwriters. I'm sure that some of those songwriters are tortured artists whose blood and sweat come out in their songs. A lot of others are fairly non-creative mediocre songwriters who figured out a formula and got good at imitation. Give an uninspired song to a really successful singer, and you can have a hit. Is this something that bothers serious songwriters? Probably. There are way more songwriters, both serious and formulaic, than there are successful singers. Maybe the uninspired songwriters have something to fear with AI replacing them. But is anybody that worried about them? I suspect not.

But what about serious non-performing songwriters who really do pour their blood, sweat, and tears into their work. Will AIs replace them?

Maybe. But they have a hard enough time already getting their songs on the air. I have a hard time believing it will make much of a difference. If .00001% of the population lose their jobs doing what they love, I guess that's kind of sad, but I wouldn't call it a tragedy. The number of artisans creating elegant and artistic horse saddles is a small fraction of what it was 150 years ago. Times change.

Cheating with AI?

I saw an article about a teacher who got an essay from a student that was well-written. Maybe too-well written. Turns out the student used an AI to write it, and turned it in as their own work. The teacher (and the article) predicted massive changes to how school work is assigned, performed, and evaluated.

I'm not sure I understand why.

Cheat Your Way Through School?

Cheating has always been with us. When I was a student, that consisted of copying (verbatim or paraphrasing) from magazines, encyclopedias, or the smart kid in a different class. And while many kids got caught, many others did not. Teachers used to tell us that cheating didn't actually help us prepare for our futures, but kids are too now-focused to understand or care about that. We just knew that our parents would take away our TV privileges if we got a bad report card, so some kids cheated.

The Internet supposedly changed all that since it became trivially easy to cheat. As though lowering the effort would open the floodgates. But it didn't. Sure, you can buy essays on-line now, which makes it easier to cheat, but most kids still don't.

And now AI is about to change all that since it is even more trivially easy (and cheaper) to cheat.

I don't buy it. Cheaters are going to cheat, and it's not obvious to me that making it easier and cheaper to cheat will make a lot more kids into cheaters. 

Cheat Your Way Through Career?

And besides, why do we care? If cheaters make it all the way through college with much higher grades than are deserved, they will more-or-less reach their true level when they start their careers. I've had to fire some programmers who I wonder whether they ever wrote a line of code in their lives. Did they cheat their way through school? Or did the schools just do a bad job of preparing programmers? I don't know, and I don't care. I managed to hire some excellent programmers in spite of getting a few duds. And I suspect the same basic pattern exists in most careers.

I'll focus my discussion on the career of computer programming, but I suspect many of the concepts will apply to other careers.

Maybe the AIs are getting so good that a poor programmer that is good at cheating will produce just as good results as the excellent programmer down the hall. How is that fair? And does it even matter?

My programmers take poorly-described requirements and figure out what the user needs, and then figure out how to incorporate those needs into our existing product. Cheaters can't do that even if they have a great AI at their disposal.

In fact, even that is not what my senior programmers do. They figure out what our users want before the users do. When 29West was just getting started (2003-ish), I don't think there was such a thing as a brokerless general pub-sub messaging system. The financial services industry wanted low latency, but also wanted the flexibility of pub-sub. The idea 29West came up with was to combine peer-to-peer with reliable multicast and the pub-sub model. Figuring out how to do that required dreaming up new ways of doing things. Even if a really good AI existed back then, it would not have been trained on it.

I guess what I'm saying is that the most advanced AI technology available today is still based on the concept of training the AI with a lot of examples. It will be able to report the state of the art, but I can't see it advancing the state of the art. 

When Does Cheating Stop Being Cheating?

There was a period of time when I was in school when we couldn't use a calculator during a math test. You had to do the arithmetic by hand (and show your work). I suspect that still exists for a month or two when kids first learn what arithmetic is, but I suspect that calculators are now standard issue for even very young students. Is that bad?

I remember hearing people complain. "What if your batteries die? How will the supermarket employee add up your total?" Today, if a store's cash register goes down, commerce stops. And it's not because the employees can't do sums in their heads.

I also remember when poor spelling and grammar were impediments to career advancement. I guess it still is -- if you send me an email with lots of misspellings, I will think a little less of you. With spelling checkers built right into the email client, what's your excuse for not using it? (My mother-in-law used to disapprove of modern schooling where Latin is no longer a required subject. Her point was that learning Latin made you better at spelling. My point is, why bother?)

Remember cursive writing? Does anybody under 30 still use it? Do we still need to be good at shoeing horses? Starting fires with two sticks?

Do we really need everybody to be good at writing essays? Maybe it's time to consign that to the computer as well.

And yes, I know that writing essays is supposed to be a tool for exercising research skills and critical thinking. But is it really? Isn't the essay more of a measurement tool? I.e. if you did a good job of researching and thinking critically, then supposedly that will be reflected in the quality of your essay. But does that really work?

I don't know. And I've definitely strayed out of my area of expertise; I'll stop mansplaining now.

P.S.

I cut and pasted this post into ChatGPT and asked it to rewrite it better. It certainly shortened it, and included most of my main points. But it also missed a few points I consider important. And it made it a lot more boring, IMO. Then again, I always have liked to hear myself speak, so I'm biased.

OpenAI GPT-3: Initial Impressions

So, ChatGPT is at capacity right now, and I'm sure not going to sit here and hit refresh every few seconds to try to get in. So I went to https://beta.openai.com/examples and tried a few.

My impressions: disappointing given all the hype, but if I hadn't seen the hype, I would be reasonably impressed.

[UPDATE: I've since gotten into the real ChatGPT, and I must say it is more impressive than the sandbox I played with in this post. The sandbox is based on GPT-3, while ChatGPT is GPT-3.5.]

In the following examples, I am including output from OpenAI's GPT-3 model. In accordance with OpenAI's wishes, my name is Steve Ford, and the text shown in green is generated by an AI.

Analogy maker

My entry is first, followed by the AI response in green.

Get the logic right, then optimize.

It's like building a house: first make sure the foundation is solid, then make it look nice.

Not bad.

Do unto others as you would have them do unto you.

It's like a golden rule of giving and receiving; treat others as you would like to be treated.

Um, I don't think you can use a definition as an analogy. The point of an analogy is to improve understanding of a concept by re-structuring it in different terms that the reader might be more familiar with.

Look out for number one.

It's like putting on your own oxygen mask before helping others on an airplane.

Impressively good and bad. Yes, it kind of understood what the phrase means, but it also completely misses the essence of the phrase. "Watch out for number one" is all about being selfish (Collins dictionary says, "If you are looking out for number one, you are thinking of yourself rather than considering other people"), whereas the analogy is about doing something that might seem selfish at first glance, but is actually in support of generosity and the greater good.

Pro tip: don't use GPT-3 to learn the meaning of idioms.

Do unto others ... and then split Give a hand to those in need ... and then walk away.

This one might not be fair; I wonder how many under-50-year-olds would get that reference. Anyway, the analogy is the exact opposite of the original.

Pro tip: don't use GPT-3 to learn about 50-year-old memes.

There are other example applications that I would like to play with, but who has time for that? Over time, I'll probably have more to say about AI.

Invert the Meaning

I took the analog maker settings and changed the command (or whatever that first line is called) to "Invert the meaning:".

Time flies like an arrow.

Time stands still like a rock.

Not idiomatic, but impressive.

Smoking is bad for you.

Not smoking is bad for you.

Yep, it will lie if you tell it to.

Write an Essay

Took the analog maker settings and changed the command to "Write an essay:"

Why structured programming is bad.

Structured programming is a programming paradigm that relies on breaking down a program into smaller, manageable parts. It is a popular approach to programming because it is easy to understand and can be used to create complex programs. However, there are a number of drawbacks to structured programming that can make it a less than ideal choice for certain projects.

The first issue with structured programming is that it can be difficult to maintain. Because the code is broken down into smaller parts, it can be difficult to keep track of how the parts fit together. This can lead to bugs and errors that can be difficult to debug. Additionally, if changes need to be made to the program, it can be difficult to make sure that all the parts are updated correctly.

Another issue with structured programming is that it can be inflexible. Structured programming relies on a set of predetermined rules and structures, which can limit the options for solving a problem. If a programmer needs to come up with a creative solution, structured programming may not be the best choice.

Finally, structured programming can be slow. The small parts of a program can take a long time to process, especially if there are a lot of them. This can lead to programs that take a long time to run, which can be a problem for projects that require fast results.

In conclusion, structured programming can be a useful approach for certain projects, but it is not without its drawbacks. It can be difficult to maintain, inflexible, and slow. For projects that require creative solutions or fast results, it may be better to use an alternative approach.

Tgen: Traffic Generator Scripting Language

Oh no, not another little language! (Perhaps better known as a "domain-specific language".)

Yep. I wrote a little scripting language module intended to assist in the design and implementation of a useful network traffic generator. It's called "tgen" and can be found at https://github.com/fordsfords/tgen. I won't write much about it here other than to mention that it implements a simple interpreter. In fact, the simplicity of the parser might be the thing I'm most pleased about it, in terms of bang for buck. See the repo for details.

Little Languages Considered Harmful?

So yeah, I'm reasonably pleased with it. But I am also torn. Because "little languages" have both a good rap (Jon Bentley, 1986) and a bad rap (Olin Shivers, 1996).

In that second paper, Shivers complains that little languages:

• Are usually ugly, idiosyncratic, and limited in expressiveness.
• Basic linguistic elements such as loops, conditionals, variables, and subroutines must be reinvented and re-implemented. It is not an approach that is likely to produce a high-quality language design.
• The designer is more interested in the task-specific aspects of his design, to the detriment of the language itself. For example, the little language often has a half-baked variable scoping discipline, weak procedural facilities, and a limited set of data types.
• In practice, it often leads to fragile programs that rely on heuristic, error-prone parsers.

Of course, Shivers doesn't *really* think that little languages are a bad idea. He just thinks that they are usually implemented poorly, and his paper shows the right way to do it (in Scheme, a Lisp variant).

But there are some good arguments against developing little languages at all, even if implemented well. At my first job out of college, I wrote a little language to help in the implementation of a menu system. The menus were tedious and error-prone to write, and the little language improved my productivity. I was proud of it. An older and wiser colleague gently told me that there are some fundamental problems with the idea. His reasoning was as follows:

• We already have a programming language that everybody knows and is rich and well-tested.
• You've just invented a new programming language. It probably has bugs in the parser and interpreter that you'll have to find and fix. Maybe the time you spend doing that is paid for by the increased productivity in adding menus. Maybe not.
• The new language is known by exactly one person on the planet. Someday you'll be on a different project or a different company, and we can't hire somebody who already knows it. There's an automatic learning curve.
• Instead of writing an interpreter for a little language, you could have simply designed a good API for the functional elements of your language, and then used the base language to call those functions. Then you have all the base language features at your disposal, while still having a high level of abstraction to deal with the menus.

He was a nice guy, so while his criticism stung, he didn't make it personal, and he was tactful. I was able to see it as a learning experience. And ever since then, I've been skeptical of most little languages.

Then Why Did I Make a Little Language?

Well, first off, I *DID* create an API. So instead of writing scripts in the scripting language, you *can* write them in C/C++. I expect this to be interesting to QA engineers wanting to create automated tests that might need sophisticated usage patterns (like waiting to receive a message before sending a burst of outgoing traffic). I would not want to expand my scripting language enough to support that kind of script. So being able to write those tests in C gives me all the power of C while still giving me the high level of abstraction for sending traffic.

But also, a network traffic generator is a useful thing to be able to run interactively for ad-hoc testing or exploration. It would be annoying to have to recompile the whole tool from source each time you want to change the number or sizes of messages.

Of course, most traffic generation tools take care of that by letting you specify the number and sizes of the messages via command-line options or GUI dialogs. But most of them don't let you have a message rate that changes over time. My colleagues and I deal with bursty data. To properly test the networking software, you should be able to create bursty traffic. Send at this rate for X milliseconds, then at a much higher rate for Y milliseconds, etc. The "tgen" module lets you "shape" your data rate in non-trivial ways.

Did I get it right? My looping construct is ugly and could only be loved by an assembly language programmer. Maybe I should have made it better? Or just omitted it? Dunno. I'm open to discussion.

Anyway, I'm hoping that others will be able to take the tgen module and do something useful with it.

Critical Program Reading (1975) - 16mm Film

 I find this film delightful: Critical Program Reading (1975) - 16mm Film

I would love to know about choices the filmmaker made. The vibe seems very 1960s; was that intentional?

I also didn't know that structured programming methods were that old. I was born in 1957. According to Wikipedia, the concept of "structured programming" was born in those years, although the term was first popularized by Dijkstra in his 1968 open letter "Goto Considered Harmful".

For some reason, I thought the "structured programming wars" were during the mid-to-late 1980s, when the old-school "spaghetti code" techniques were finally being replaced by more modern techniques. I guess I thought this because I clearly remember the "Goto Considered Harmful" Considered Harmful letter, and its replies. But the true war against spaghetti code was pretty much over by then. The battle at that point was not about if we should use descriptive identifier naming, block structure, and simple control flow. It was about whether the abolition of the goto should be absolute.

<rant read="optional">

I also remember feeling insulted by Dijkstra's On a Somewhat Disappointing Correspondence. He said that a competent professional programmer in 1987 should know the theorem of "the bounded linear search" and should be able to derive that theorem and its proof. I could not even read the theorem since I was not familiar with the notation. And none of my colleagues could either. I suspect that a small percentage of professional programmers of the day (and today also) would qualify as competent by Dijkstra's standards.

In retrospect, I do have some sympathy for Dijkstra's opinion. He knew full well that his standards did not match those of the programming profession. That's exactly what he was complaining about. He strongly felt that programmers should be grounded in the science of computer science. He wanted programmers to spend their time proving their algorithms correct, not slavishly (and inadequately) testing them. I suspect he wasn't saying that the programmers of the day were bad or stupid people, but that they were improperly educated and then released into the field prematurely. I suspect he might agree with, "You are not competent, but it's probably not your fault. It's more the fault of the university that gave you a degree and the company that hired you." Part of me that wishes that I and the rest of the world were more dedicated to rigor and depth of mastery.

But, of course, we are not. Airline pilots are not trained to design an airplane. House painters can't give you the chemical formulae of their paints. I remember when my wife had cancer, she was advised against using a surgeon who was a highly respected researcher; she should use a doctor who does hundreds of these surgeries per year. You usually want an experienced practitioner, not a theoretician.

Is the same thing true of programmers? Well, I will note that Dijkstra's program uses single-letter variables, a definite no-no in most structured programming. If he had submitted that to me as part of a job application, I doubt I would have hired him. But maybe that's because *I* am not competent. Maybe software would be much better today if we programmers met Dijkstra's standards. But there would be a heck of a lot less software out there, that's for sure. And cynical humor aside, I do rather like having a smart phone with a GPS.

</rant>

So long, Delta

Note to my technically-oriented readers (all two of you). You might want to skip this post. It is not technical in nature.

I used to use Delta Airlines a lot. Not anymore.

https://www.cnbc.com/amp/2022/10/22/delta-air-lines-settles-with-pilot-who-raised-safety-concerns.html

https://www.seattletimes.com/business/boeing-aerospace/delta-weaponized-mental-health-rules-against-a-pilot-she-fought-back/

So, am I refusing to fly Delta because they were unfair and downright evil to an employee? Heck no. Happens all the time. Sometimes employers get caught, and they have to make amends. Sometimes they don't get caught, and they get away with it. If I refused to deal with companies who misbehave, I would have to become a hermit doing subsistence farming with rocks and sticks.

No, I'm refusing because even after Delta's dirty tricks were exposed and their claims totally debunked, the manager behind it all was "...promoted to CEO of Endeavor, Delta’s regional carrier subsidiary, and senior vice president of Delta Connection, the airline’s partnership with regional carriers Skywest and Republic Airways."

DUDES! When you get caught, you're supposed to at least pretend to be sorry! And somebody has to become the sacrificial lamb. But I guess that only happens when the lamb is a low-level employee. When it's a bigwig, then better to just close ranks, settle, and pretend everything's cool. Nothing to see here, move along.

Sorry, no can do. And yes, I know, I don't have all the facts. Maybe more facts will come to light. Maybe Graham truly believed he was doing the ethical and moral thing.

What do you say, Graham? Did you genuinely believe in your heart that Petitt wasn't safe to fly? Based on her complaints about safety? Feel free to post a reply here. If it sounds credible, I'll post a retraction and fly Delta again.

Hopefully I can sleep tonight over the sound of crickets.

The Time I Found a Hardware Bug

As I approach age 65, I've been doing some reminiscing. And discovering that my memory is imperfect. (pause for laughter) So I'm writing down a story from earlier days in my career. The story has no real lessons that are applicable today, so don't expect to gain any useful insights. But I remember the story fondly so I don't want it to slip completely from my brain.

WARNING: this story is pretty much self-indulgent bragging. "Wow, that Steve guy sure was smart! I wonder what happened."

I think it was 1987, +/- 2 years (it was definitely prior to Siemens moving to Hoffman Estates in 1989).

The product was "Digitron", an X-ray system based on a Multibus II backplane and an 8086 (or was it 80286?) CPU board running iRMX/86. I think the CPU board was off-the-shelf from Intel, but most of the rest of the boards were custom, designed in-house.

At some point, we discovered there was a problem. We got frequent "spurious interrupts". I *think* these spurious interrupts degraded system performance to the degree that sometimes the CPU couldn't keep up with its work, resulting in a system failure. But I'm not sure -- maybe they just didn't like having the mysterious interrupts. At any rate, I worked on diagnosing it.

The CPU board used an 8259A interrupt controller chip (datasheet here or here) that supported 8 vectored interrupts. There was a specific hardware handshake between the 8259A and the CPU chip that let the 8259A tell the CPU the interrupt vector. The interrupt line is asserted and had to be held active while the handshake took place. At the end of the hardware handshake, the CPU calls the ISR, which interacts with the interrupting hardware. The ISR clears the interrupt (i.e. makes the hardware stop asserting the interrupt line) before returning.

According to the 8259A datasheet, spurious interrupts are the result of an interrupt line being asserted, but then removed, before the 8259A can complete the handshake. Essentially the chip isn't smart enough to remember which interrupt line was asserted if it went away too quickly. So the 8259A declares it "spurious" and defaults to level 7.

I don't remember how I narrowed it down, but I somehow identified the peripheral board that was responsible.

For most of the peripheral boards, there was a single source of interrupt, which used an interrupt line on the Multibus. But there was one custom board (don't remember which one) where they wanted multiple sources of interrupt, so the hardware designer included an 8259A on that board. Ideally, it would have been wired to the CPU board's 8259A in its cascade arrangement, but the Multibus didn't allow for that. So the on-board 8259A simply asserted one of the Multibus interrupt lines and left it to the software to determine the proper interrupt source. The 8259A was put in "polled mode" and ISR for the board's interrupt would read the status of the peripheral 8259A to determine which of the board's "sub-interrupts" had happened. The ISR would then call the correct handler for that sub-interrupt.

Using an analog storage scope, I was able to prove that the peripheral board's 8259A did something wrong when used in its polled mode. The peripheral board's 8259A asserted the Multibus interrupt level, which led to the CPU board properly decoding the interrupt level and invoking the ISR. The ISR then performed the polling sequence, which consisted of reading the status and then writing something to clear the interrupt. However, the scope showed that during the status read operation, while the multibus read line was asserted, the 8259A released its interrupt output. When the read completed, the 8259A re-asserted its interrupt. This "glitch" informed the CPU board's 8259A that there was another interrupt starting. Then, when the ISR cleared the interrupt, the 8259A again released its interrupt. But from the CPU board's 8259A's point of view, that "second" interrupt was not asserted long enough for it to handshake with the CPU, so it was treated as a spurious interrupt.

(Pedantic aside: although I use the word "glitch" to describe the behavior, that's not right terminology. A glitch is typically caused by a hardware race condition and would have zero width if all hardware had zero propagation delay. This wasn't a glitch because the release and re-assert of the interrupt line was tied to the bus read line. No race condition. But it resembled a glitch, so I'll keep using that word.)

HARDWARE BUG?

The polling mode of operation of the 8259A was a documented and supported use case. I consider it a bug in the chip design that it would glitch the interrupt output during the status read operation. But I didn't have the contacts within Intel to raise the issue, so I doubt any Intel engineer found out about it.

WORKAROUND

I designed a simple workaround that consisted of a chip - I think it was a triple, 3-input NAND gate, or maybe NOR, possibly open collector - wired to be an AND function. The interrupt line was active low, so by driving it with an AND, it was possible to force it to active (low). I glued the chip upside-down onto the CPU board and wire-wrapped directly to the pins. One NAND gate was used as an inverter to make another NAND gate into an AND circuit. One input to the resulting AND was driven by the interrupt line from the Multibus, and the other input was driven by an output line from a PIO chip that the CPU board came with but wasn't being used. I assume I had to cut at least one trace and solder wire-wrap wire to pads, but I don't remember the details.

The PIO output bit is normally inactive, so that when the peripheral board asserts an interrupt, the interrupt is delivered to the CPU. When the ISR starts executing, the code writes the active value to the PIO bit, which forces the AND output to stay low. Then the 8259A is polled, which glitched the multibus interrupt line, but the AND gate keeps the interrupt active, masking the glitch. Then the ISR writes a inactive to the PIO and clears the interrupt, which releases the Multibus interrupt line. No more spurious interrupt.

Kludge? Hell yes! And a hardware engineer assigned to the problem figuratively patted me on the head and said they would devise a "proper" solution to the spurious interrupt problem. After several weeks, that "proper" solution consisted of using a wire-wrap socket with its pins bent upwards so that instead of wire-wrapping directly to the chip's pins, they wire-wrapped to proper posts.

Back in those days, people didn't have a digital camera in their pocket, so I have no copy of the picture I took of the glitch. And I'm not confident that all the details above are remembered correctly. E.g. I kind of remember it was a NOR gate, but that doesn't make logical sense. Unless maybe I used all 3 gates and boolean algebra to make an AND out of NOR gates? I don't remember. But for sure the point was to mask the glitch during the execution of the ISR.

But I remember the feeling of vindication. My hardware training made me valuable over a pure software engineer.

Math Nerd?

I just made two posts on recreational math. I'm what you might call a math nerd wannabe. I'm NOT a math nerd - I don't have a flair or the rigor required to make that claim - but I've always wished I were.

I used to read Martin Gardner in Scientific American. And I tried to enjoy it with mixed success. More recently, I subscribed to Numberphile, but finally unsubscribed when I realized I tend to lose focus about halfway through most of the videos. And 3Blue1Brown? The same but more. It's not just that I have trouble following the math (although I often do), I'm just not interested enough to try hard enough. But darn it, I wanna be! :-)

When I was very young, I aspired to be a scientist so I could invent cool things. Never mind that theoretical scientists and inventors tend to be very different kinds of people; in both cases, I don't have the knack. I think I'm more of a hobbyist who discovered that he could be paid well for his hobby. I've never invented a cool algorithm, but I've enjoyed implementing cool algorithms that real scientists have invented. I like tinkering, taking things apart to see what makes them tick, and sometimes even putting them back together.

Not that there's anything wrong with this. I've led, and continue to lead, a happy, productive, and fulfilling life. I'm reasonably well-liked and respected by my peers. I have no complaints about how life has treated me.

But I am sometimes wistful about what might have been ... being a math nerd/scientist/inventor would be pretty cool too.

Anyway, I won't be making regular posts about math ... unless I do. ;-)