release winning entries of IOCCC28 under the year 2024
Congratulations to: * 2024/anders - Prize in sound coding - layered music generator * 2024/burton - Prize in pentagrammatology - wordle hard mode solver * 2024/cable1 - Prize in bot talk - LLM inference engine * 2024/cable2 - Prize in murky waters - salmon recipe * 2024/carlini - Prize in perfect timing - Intel 4004 emulation * 2024/codemeow - Prize in tray planting - bonsai generator * 2024/endoh1 - Prize in patient pointillism - slow ray tracer in CPP * 2024/endoh2 - Prize in solid body physics - rotating rigid body simulation * 2024/ferguson1 - Prize in diabolical logistics - Oregon trail pact with the devil * 2024/ferguson2 - Prize in yil-tas - Navajo code talker translator * 2024/howe - Nice accent eh-ward - mini vi * 2024/kramer - Prize in linguistic arithmetic - natural language numerical calculator * 2024/kurdyukov1 - Prize in phased periodicity - phase of the Moon * 2024/kurdyukov2 - Prize in art restoration - JPEG artifact removal * 2024/kurdyukov3 - Prize in virtual quietus - gaming VM and doom * 2024/kurdyukov4 - Prize in embiggening - encode without literals * 2024/maffiodo - Prize in creative interpretation - Jav\*script interpreter * 2024/mills - Prize in ℤ₃ - Infocom v3 story interpreter * 2024/stedolan - Best one liner - icon from MD5 * 2024/straadt - Prize in imitative rebooting - OpenRISC CPU and Linux * 2024/tmarrec - Prize in cyclonic coding - 3D tornado simulation * 2024/tompng - Prize in quasi bijection - vortex encryptor decryptor * 2024/weaver - Sur prize - rickroll Ran `make update` to perform the above. new file: 2024/burton/.entry.json
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## To build:
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``` <!---sh-->
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make all
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```
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## To use:
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``` <!---sh-->
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./prog foo.z3 foo.sav
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```
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The `foo.z3` is an [Infocom][2] version 3 [Z-machine][3] file,
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and `foo.sav` is file that is written when you enter the command `SAVE`
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and read when you enter the command `RESTORE`.
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## Try:
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``` <!---sh-->
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./try.sh
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For your first try, we suggest selecting games 0 or 1
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```
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## Alternate code:
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### Alternate build:
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``` <!---sh-->
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make alt
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```
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### Alternate use:
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``` <!---sh-->
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./try.alt.sh
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For your first try, we suggest selecting games 0 or 1
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```
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## Judges' remarks:
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What is the "**Prize in ℤ₃**"? The "_double-struck Z_" is **NOT**
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a reference to a set of integers, nor is the "_double-struck Z subscript
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3_" a reference to a ring of 3-adic integers. Instead, it is a reference
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to the 3rd version of a certain [virtual machine](https://en.wikipedia.org/wiki/Z-machine).
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To fully appreciate the brilliance of this implementation, we suggest
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illuminating the source code. But be careful not to get lost in the
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labyrinthine twists and turns of this source code and get eaten by a Grue!
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## Author's remarks:
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### West of House
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```
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You are standing in an open field west of a white house, with a boarded
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front door.
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There is a small mailbox here.
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```
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These are the opening lines from the legendary [Zork][1], one of the most
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influential and successful games of the early computer era. You can play a
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demo version with the submitted program using the following command:
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``` <!---sh-->
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./prog minizork.z3 minizork.sav
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``` <!---sh-->
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_Minizork_ is a publicly-available demo version of the original _Zork_, but
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the program can play any of the classic [Infocom][2] text adventure games that
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run on the version 3 of the [Z-machine][3], a [virtual machine][4] which
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Infocom used to run its mainframe-developed games on the 8-bit microcomputers
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of the 1980's.
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Although there were several iterations of the Z-machine, this program
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implements version 3, which was used for dozens of Infocom's most famous and
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influential [interactive fiction][5] games of the 1980's, including:
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- The _Zork_ Trilogy (_Zork I_, _Zork II_ and _Zork III_) and the related
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Enchanter Trilogy (_Enchanter_, _Sorcerer_ and _Spellbreaker_)
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- The _Planetfall_ series (_Planetfall_ and _Stationfall_)
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- _The Hitchhiker's Guide to the Galaxy_ (by Douglas Adams)
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- _The Lurking Horror_ (Lovecraftian horror)
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- _Plundered Hearts_ (romance)
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- _Leather Godesses of Phobos_ (best left unsaid)
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If you are new to interactive fiction, you might want to try one of the two
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Infocom "four-in-one" demo samplers. These include a gentle introductory
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tutorial to interactive fiction and some sample puzzles from _Zork I_,
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_Planetfall_, _Infidel_, _The Witness_, _Trinity_ and _Leather Godesses of
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Phobos_. You can run them by typing:
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``` <!---sh-->
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./prog sampler1_R55.z3 sampler1.sav
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```
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or
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``` <!---sh-->
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./prog sampler2.z3 sampler2.sav
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```
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In addition to the Infocom games, there is an entire community of interactive
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fiction authors who write modern games which can be downloaded from sites
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like [The Interactive Fiction Database][6], [The Interactive Fiction Wiki][7],
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and [The Interactive Fiction Archive][8]. I've included a few "story files"
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compiled for the Z3 machine from these sites for your enjoyment, but I'll
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point out in particular [Curses][9] by Graham Nelson, the author of
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[Inform][10], a literate programming system for writing interactive fiction.
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You can of course run it with
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``` <!---sh-->
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./prog curses-r10.z3 curses.sav
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```
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By now you've probably figured out that `prog` takes two command-line
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arguments, the first being the "story file" which is the game itself, and
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the second (optional) parameter being the "save file", which is the file
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the game will write if you type `SAVE` and read if you type `RESTORE`.
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The second parameter is optional, but if you don't use it, you won't be able
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to `SAVE` your game (think of this as an "Ironman" mode). Make sure that if
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you switch story files, you also switch save files, because a `RESTORE` from
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an unrelated story file will invoke what the C Standard Committee refers to
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as ["Undefined Behavior"][22].
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You can use this command-line template to run any other "version 3" games you
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find, including the original Infocom ones. If you are lucky, you can find
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the original files in one of the (sadly out-of-print) collections like
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[The Lost Treasures of Infocom][11], or you could download a copy of the
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[Zork Trilogy][12] (which was given away free as part of an Activision
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promotion long ago). There are of course other places one might find Infocom
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story files, but since they are not in the public domain I cannot give
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pointers to them. Maybe Microsoft will decide to release them from
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abandonware status now that they have bought Activision...
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Finally, I have also included a copy of [Colossal Cave Adventure][13], which
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may be better known by it's PDP-10 file name _ADVENT_. You can run it with
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``` <!---sh-->
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./prog advent.z3 advent.sav
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```
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_ADVENT_ is the original interactive fiction title by Crowther and Woods that
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inspired _Zork_ and gave us hacker shibboleths like [Xyzzy][14] and "You are
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in a maze of twisty little passages, all alike."
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### It is pitch black. You are likely to be eaten by a grue.
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So what makes the Z3 machine an interesting obfuscation target? Good question!
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The IOCCC has seen all manner of virtual machines over the years, from
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Commodore PETs to IBM PC's that can run Windows™ and even a mainframe or
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two, so what is so challenging about a VM that ran on the TRS-80 and the
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Apple II?
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Well, a lot really. If you've got nothing better to do, take a look at the
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[Z-Machine Standards Document][15] which is a detailed reverse-engineering
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effort of Infocom's interpreter. A Z-machine implementation has to handle
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the byte-code for an exceptionally complicated byte-code interpreter, which
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in turn has to do a lot of high-level operations such as:
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- Text encryption, decryption and decompression using a packed 5-bit modal
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encoding and tables of "abbreviations"
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- Lexical input parsing and mapping words through a compressed dictionary
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and a "word separator" table
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- Screen output that includes automatic word-wrapping and a status line
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that shows the current room, number of moves and score (or current time,
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for timed games like _Deadline_).
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- Maintaining an "Object tree" that holds the state of the objects in the
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game, their containment relationships, _attributes_ (openable, open, worn,
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concealed, locked, etc.) and _properties_ (name, description, capacity,
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exits, methods, etc.)
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- Support for "virtual memory" -- the virtual machine's address space was
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larger than the 16-bit addressing of the computers of the era, and certainly
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larger than the 32 kilobytes of physical memory. These restrictions require
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the interpreter to deal with multiple types of addresses to get at the
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different types of storage.
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- File I/O for saving, restoring and restarting the game.
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- Dynamic memory areas such as the "header" and various other tables that
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are used as sideband global communication between the interpreter and the
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story file. Either or both can change the state, so it needs to be
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explicitly checked.
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- An exceptionally [CISC][16]-like variable-length bytecode with variadic
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parameters and complicated encodings.
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The interpreter is complicated because of the Herculean task the _Zork_
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implementors set for themselves. _Zork_ itself was originally written on a
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PDP-10 mainframe at MIT running a version of Lisp called [MDL][17]. It was
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designed to have a more natural parser than the two-word parser of _ADVENT_.
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_Zork_ itself escaped into the wild because of MIT's connection to
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[ARPANET][18]. Contributions and requests from the player-base caused the
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program to grow in size until it filled the mainframe's megabyte of memory.
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When the newly-founded Infocom decided to port their grad-school project to
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the world of microcomputers, they needed to somehow move a megabyte of MDL
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code onto 8-bit microcomputers with 32 kilobytes of memory. They got there by
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chopping the program into three separate parts, creating a stripped-down
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subset of MDL called [ZIL][19] (for Zork Implementation Language) and
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targeting the compiled ZIL bytecode to run on the Z-machine interpreter. The
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Z-machine data types were specifically designed to reduce the memory footprint
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as much as possible (including packed properties and compressed string
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encodings) but the ZIL code was still too large (at over 100 kilobytes), so
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the interpreter was designed to page in parts of the story file from the
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floppy disk, one of the first uses of [virtual memory][20] on personal
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computers.
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All of the above was described in a much clearer fashion by Infocom employees
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in a paper called [How to Fit a Large Program into a Small Machine][21],
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which I only discovered after writing the previous paragraph, alas. I include
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it here for the curious, because you can never have enough links in your
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IOCCC write-up.
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### A hollow voice says "Fool."
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It took me many iterations to make the interpreter fit inside the IOCCC size
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limits.
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The original quite compact C program was maybe still 50% too large even after
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doing as much minification as possible. I won't go into the details of the
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next iterations of reduction (that would spoil all the fun), but suffice to
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say, the steps I took share some similarities to the steps the _Zork_
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implementors took to do their heroic reduction. It was only by completely
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throwing out any attempt to make the source code look "pretty" was I able to
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cross the `iocccsize` Rule 2b limitation of 2,053, and this included abusing
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the whitespace rules.
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Of course, by time the contest was announced, the size limit had increased
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which means I had to go back and undo some of my heroics because now I had
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enough wiggle room to make the source more picturesque. I have however
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included a version of the original source (`prog.alt.c`) for your perusal and
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amusement.
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[1]: https://en.wikipedia.org/wiki/Zork "Zork"
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[2]: https://en.wikipedia.org/wiki/Infocom "Infocom"
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[3]: https://en.wikipedia.org/wiki/Z-machine "Z-machine"
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[4]: https://en.wikipedia.org/wiki/Virtual_machine "Virtual machine"
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[5]: https://en.wikipedia.org/wiki/Interactive_fiction "Interactive fiction"
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[6]: https://ifdb.org "IFDB"
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[7]: https://www.ifwiki.org "IFWiki"
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[8]: https://www.ifarchive.org "IFArchive"
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[9]: https://ifdb.org/viewgame?id=plvzam05bmz3enh8 "Curses"
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[10]: https://ganelson.github.io/inform-website "Inform 7"
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[11]: https://en.wikipedia.org/wiki/The_Lost_Treasures_of_Infocom
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"The Lost Treasures of Infocom"
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[12]: http://www.infocom-if.org/downloads/downloads.html "Zork Trilogy"
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[13]: https://en.wikipedia.org/wiki/Colossal_Cave_Adventure
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"Collosal Cave Adventure"
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[14]: https://en.wikipedia.org/wiki/Xyzzy_(computing) "Xyzzy"
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[15]: https://www.inform-fiction.org/zmachine/standards "Z-Machine Standards"
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[16]: https://en.wikipedia.org/wiki/Complex_instruction_set_computer "CISC"
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[17]: https://en.wikipedia.org/wiki/MDL_(programming_language) "MDL"
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[18]: https://en.wikipedia.org/wiki/ARPANET "ARPANET"
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[19]: https://www.ifwiki.org/ZIL "ZIL"
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[20]: https://en.wikipedia.org/wiki/Virtual_memory "Virtual Memory"
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[21]: https://mud.co.uk/richard/htflpism.htm "ZIL paper"
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[22]: https://en.wikipedia.org/wiki/Undefined_behavior "Undefined Behavior"
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<!--
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Copyright © 1984-2025 by Landon Curt Noll and Leonid A. Broukhis. All Rights Reserved.
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You are free to share and adapt this file under the terms of this license:
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Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
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For more information, see:
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https://creativecommons.org/licenses/by-sa/4.0/
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-->
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