fix 2024/anders swap 2024/straadt
We swapped `2024/anders` and `2024/straadt` by accident.
Sorry (tm Canada 🇨🇦) about that!
We **SINCERELY APOLOGIZE** to both **Anders Kaare Straadt**
and **Sebastian Macke** for the mix up!
We normalized some of the `.gitignore` files for some
of the 2024 winning entries.
Rebuilt 2024 tar files.
Updated `sitemap.xml`.
Ran `make update` to perform the above.
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Landon Curt Noll committed
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@@ -15,159 +15,68 @@
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## Try:
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``` <!---sh-->
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./try.sh
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./prog
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```
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and then play the resulting `prog.wav` using a sound player.
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## Judges' remarks:
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When we ran this entry the first time (in a virtual machine window), it felt like the VM has rebooted.
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Then, after the initial feeling had subsided, we were able to appreciate the entry in greater detail.
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When you run the program, after several moments, a `prog.wav` sound file is produced.
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Have you ever wondered would what would happen if you recursively removed
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files starting from the root directory? Are you curious what happens when
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you launch a [fork bomb](https://en.wikipedia.org/wiki/Fork_bomb)?
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Within the safety of an virtual walls, can safely give those and other scenarios:
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just check out the "[Things You Can Do](#todo")" section below.
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Using a sound player (you may find `sox(1)` is a good choice), you may enjoy the result.
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**NOTE**: For those who do not have a clang compiler environment that
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supports the `wasm32` target, we provide a `prog.wasm` file.
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**SUGGESTION / REQUEST**: Having a way to build custom boot-up images for this entry would be of interest.
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Can you figure out how it produces the various layers of instruments?
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## Author's remarks:
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### Emulator Running Linux
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### Obfuscations
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- "Helpful" formatting
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- Character salad
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- Loop exit trying to hide by a switch statement
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- Strong string encryption. By that I mean "fmt"=>"gnu".
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- A `/*{*/` that throws off bracket matching in vim. Begun the editor wars
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have! (Wait, I'm **on** the vim-team!)
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- `cm` and `ap` stands for "allpass" and "comb", respectively.
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- One effect was created with deliberate "memory corruption".
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#### What It Does
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To encourage tinkering I've obfuscated the song data and program (see Y()) less
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than the "library code". Sorry if you wanted to tinker with the library code!
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This is an emulator capable of running a full modern Linux system with a minimal set of features. The system includes:
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### Sound quality
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* An OpenRISC 32-Bit CPU
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* A Memory Management Unit
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* A UART connected to the Terminal
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* An Interrupt Controller
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* A Timer Controller
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The sample rate of prog.wav is 256kHz because creating aliasing-free waveforms
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would require more code, but you can always oversample the audio and pass the
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anti-aliasing problem on to the audio player :-) However, the downsampler in my
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`mplayer(1)` is poor, but you can use the high-quality resampler in `sox(1)` to create a
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48kHz version:
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<div id="todo">
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### Things You Can Do
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</div>
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#### Look Up Specs
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First, you can look up the specs of the emulated system. The following commands will give you a good overview:
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``` <!---sh-->
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uname -a
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free -h
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cat /proc/cpuinfo
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cat /proc/meminfo
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cat /proc/interrupts
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cat /proc/timer_list
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``` <!---c--->
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sox prog.wav -r 48000 prog.48kHz.wav
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```
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### Tricks (the condescending part)
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#### Fork Bomb Visualized
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- Kick drum from sines, pitched up to create toms.
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- Roland TR-808 style hi-hats (a bunch of high-pass filtered square waves).
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- SID/C64-style snare drum (oscillates between noise and square wave).
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- There's some FM synthesis in the bass.
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- Schroeder reverberator a la Freeverb. The same building blocks are used for
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the echo effect.
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- Waveshaping/overdrive using tanh(x), ohh yeaaah..
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For educational purposes, type the following two lines and watch the process tree grow:
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I used this Python snippet to generate `q0[2]` and `q0[3]`:
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``` <!---sh-->
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b(){ sleep 2; b|b; }
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(b &) && watch -n1 pstree -p
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``` <!---python-->
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def X(s): print(hex(int(s.replace("x","1").replace(".","0")[::-1],2))) # not for iopcc-use
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X(".x.x..xx.x.xx.xxx.xx.xxx..xx.xxx")
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X("x.xx.x.x.x.xxxxxx.xx.xxx.xxxxxxx")
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```
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Or just run:
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``` <!---sh-->
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./fork_bomb.sh
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```
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Note: You won't be able to stop the emulator anymore and will need to kill the process.
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#### Delete Filesystem
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Ever wanted to know what happens when you delete your computer's filesystem?
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Now is your chance to find out!
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``` <!---sh-->
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rm -rf /
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```
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Even after removal, your system will still be in a well-defined state.
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For example, you can still run commands such as:
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``` <!---sh-->
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cd /proc
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echo *
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```
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Be careful: You won't be able to stop the emulation anymore and will need to kill the process.
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#### Run C64 Emulation
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A full-fledged C64 emulator is included. Run it via:
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``` <!---sh-->
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./c64
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```
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Since the C64 is little-endian and runs on a big-endian machine, which itself runs on a little-endian machine, it combines the best of both worlds into a cool intermediate format. Might this be the future of endianness? 🤔
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#### Run Itself
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With `./prog`, you can run the emulator within itself. This is a bit meta, but it works.
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The emulator would be able to run Linux as well, but it is tweaked to run with less memory and on a big-endian machine.
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#### Full scripting capabilities
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With `vi`, you got an awesome editor and can write scripts in *ash* such as.
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``` <!---sh-->
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i=1
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while [ "$i" -le 10 ]
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do
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echo "Hello World"
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i=$(expr "$i" + 1)
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done
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```
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#### Run in the Web Browser
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Did you know that you can run this emulator in a web browser?
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First, compile with Clang on systems that support a target of `wasm32`:
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``` <!---sh-->
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make prog.wasm
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```
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Then, for example, run a local web server with the following command:
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``` <!---sh-->
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python3 -m http.server 8000
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```
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Open your browser and go to `http://localhost:8000/prog.html`. You can now run the emulator in the browser.
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### Obsfucation
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The obfuscation is mainly a result of compression, plus a healthy dose of recursion and the usual endian mischief.
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For some reason, LLMs might think that this is a Smoothed Particle Hydrodynamics (SPH) simulation.
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Sigh, so much space left. More than enough for multi-core support, a full-fledged windowing system, or networking.
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Well, there's always next year.
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<!--
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