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<h1>The International Obfuscated C Code Contest</h1>
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<h2>2019/dogon - Best use of space and time</h2>
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<h3>X11 Golly game of Life</h3>
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<a class="Left" href="../diels-grabsch2/index.html">← 2019/diels-grabsch2</a>
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<a class="Right" href="https://validator.w3.org/nu/?doc=https%3A%2F%2Fwww.ioccc.org%2F2019%2Fdogon%2Findex.html">✓</a>
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<h2 id="author">Author:</h2>
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<ul>
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<li>Name: <a href="../../authors.html#Gil_Dogon">Gil Dogon</a><br>
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Location: <a href="../../location.html#IL">IL</a> - <em>State of Israel</em> (<em>Israel</em>)</li>
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<!-- BEFORE: 1st line of markdown file: 2019/dogon/README.md -->
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<h2 id="to-build">To build:</h2>
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<pre><code> make</code></pre>
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<p><strong>NOTE</strong>: this entry requires the <code>X11/Xlib.h</code> header file and the X11 library to
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compile. For more information see the
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||
FAQ on “<a href="../../faq.html#X11">X11</a>”.</p>
|
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<h3 id="bugs-and-misfeatures">Bugs and (Mis)features:</h3>
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||
<p>The current status of this entry is:</p>
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||
<blockquote>
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||
<p><strong>STATUS: uses gets() - change to fgets() if possible</strong></p>
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</blockquote>
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<p>For more detailed information see <a href="../../bugs.html#2019_dogon">2019/dogon in bugs.html</a>.</p>
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<h2 id="to-use">To use:</h2>
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<pre><code> ./prog < pattern.mc</code></pre>
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<h2 id="try">Try:</h2>
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<pre><code> ./try.sh</code></pre>
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<p>Make sure that you keep focus of windows in mind when going back and forth to
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the program and the script.</p>
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<h2 id="judges-remarks">Judges’ remarks:</h2>
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<p><a href="../../1991/davidguy/index.html">1991/davidguy</a>,
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<a href="../../2011/blakely/index.html">2011/blakely</a>, …</p>
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<p>…This entry likely concludes the IOCCC category “Cellular automata simulators”;
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it would be very hard to beat it on its field.</p>
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<p><strong>FYI</strong>: The <code>.mc</code> extension stands for <code>Golly macrocell</code> format.</p>
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<p>We truly have not much more to add, except two things:</p>
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<ul>
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<li><p>If a large sparse pattern is given, at the start of the program
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you are much more likely to see a blank board rather than the loaded configuration,
|
||
and to see it, you may need to zoom out a few times.</p></li>
|
||
<li><p>If you’re using a virtual machine with less than 4 Gb of available
|
||
model RAM, you’d want to reduce the value of the Z define in the Makefile
|
||
to <code>0x10000000</code>, otherwise the entry will promptly crash. To do this you can do:</p></li>
|
||
</ul>
|
||
<pre><code> make clobber MEMORY=0x10000000 all</code></pre>
|
||
<p>Notice that that value must be a power of two!</p>
|
||
<p>In the interest of saving lives, this entry was not fuzzed.</p>
|
||
<h2 id="authors-remarks">Author’s remarks:</h2>
|
||
<h3 id="what-is-it">What is it?</h3>
|
||
<p>Just run with no arguments on an X11-compatible system using one of the supplied
|
||
input <code>.mc</code> files as standard input. Press <code>-</code> several time to zoom out if
|
||
necessary, then press space. For acceleration press <code>]</code> several times. That’s
|
||
rather quick don’t you think?</p>
|
||
<h3 id="historical-timeline">Historical Timeline</h3>
|
||
<ul>
|
||
<li>Circa 3.77 - 4.28 Billion years ago: Microorganisms appear on Earth.</li>
|
||
<li>3000 BC: Ankh symbol is used in Egyptian hieroglyph to represent life.</li>
|
||
<li>1940s: John Von Neumann and Stanislav Ulam are interested in artificial life
|
||
eventually kick starting research on Cellular Automata.</li>
|
||
<li>1970: J.H. Conway’s research discovers a rather minimal set of rules that
|
||
seems quite interesting. <a href="https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life">Conway’s Game of
|
||
Life</a> gets published in
|
||
<a href="https://web.stanford.edu/class/sts145/Library/life.pdf">Martin Gardner’s Scientific American
|
||
column</a>.</li>
|
||
<li>1970s: According to Knuth, a significant portion of computer time in the
|
||
world is spent simulating GOL, mostly without the awareness of the people
|
||
footing the bill.</li>
|
||
<li>1984: Bill Gosper invents the
|
||
<a href="https://en.wikipedia.org/wiki/Hashlife">Hashlife</a> algorithm. His
|
||
implementation runs on Symbolics Lisp Machines. Unrelated to that, but in a
|
||
cosmic coincidence the <a href="../../years.html#1984">first IOCCC</a> is run!</li>
|
||
<li>December 2000: Tom Rokicki has a breakthrough implementing
|
||
<a href="https://en.wikipedia.org/wiki/Hashlife">Hashlife</a> in C, efficient, stable and
|
||
production ready for modern machines.</li>
|
||
<li>2006: First version of Golly by Andrew Trevorrow and Tomas Rokicki. Brings
|
||
the delights of <a href="https://en.wikipedia.org/wiki/Hashlife">hashlife</a> to the masses.</li>
|
||
</ul>
|
||
<p>Which brings us to the present moment in time.</p>
|
||
<h3 id="full-documentation-and-keys-ui">Full documentation and keys UI</h3>
|
||
<p>Yes, this program is a Conway’s Game of Life graphic simulator implementing Bill
|
||
Gosper’s hashlife algorithm. The entry’s UI is rather terse and somewhat
|
||
obfuscated, as it should be. Also, when you, accidentally or not, press any of
|
||
the keys not specified below, some stuff will happen or not, there is no
|
||
guarantee whatsoever.</p>
|
||
<p>The program should be used as follows:</p>
|
||
<p>The standard input should contain a Golly macrocell format file for a two state
|
||
automaton. See: <a href="http://golly.sourceforge.net/Help/formats.html" class="uri">http://golly.sourceforge.net/Help/formats.html</a>. Of course only
|
||
Conway’s GOL rules are supported, so rules in the files are ignored. The supplied
|
||
input examples should be quite interesting. Except one, all are taken from
|
||
Golly’s standard distribution. Information and credits to their designer are in
|
||
the header comment of each.</p>
|
||
<ul>
|
||
<li>For image navigation use the arrow keys, and zoom in and out by the <code>+</code>/<code>-</code> keys
|
||
(without pressing the shift on the <code>+</code>)</li>
|
||
<li>Space : Toggle start/stop.</li>
|
||
<li>0 (zero): Toggle single step/free run mode.</li>
|
||
<li>Backspace: Toggle direction for the arrow of time.</li>
|
||
<li><code>]</code>: Increase speed (time step) by a factor of 2.</li>
|
||
<li><code>[</code>: Decrease speed (time step) by a factor of 2.</li>
|
||
</ul>
|
||
<p>Notice that when going backward in time we ignore the current time step setting
|
||
and just jump by the amount that was specified before. However going forward is
|
||
always using the current time step.</p>
|
||
<p>There is a minimal text printout by the program, so you can know what Generation
|
||
your are in (<code>G:</code>), Internal memory allocated till now (<code>M:</code>), and then which Level
|
||
is the current macrocell (<code>L</code>) and which zoom Scale you are watching (<code>S</code>).</p>
|
||
<h3 id="portability-issues">Portability issues</h3>
|
||
<p>This entry is quite portable hopefully on most modern platforms. It assumes X
|
||
Window support of course. More than 2GB of memory is recommended. Configuration
|
||
through <a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/Makefile">Makefile</a> is provided for the display windows size and for
|
||
the memory usage. The Makefile provided configuration (<code>Z=0x20000000</code>) will need a
|
||
system with 4GB DRAM to run nicely. There are several other salient assumptions
|
||
though:</p>
|
||
<ul>
|
||
<li>The entry assumes <code>sizeof(long)==8</code>. However it actually almost avoids using any
|
||
pointers which are 64 bits these days, in order to save space. On machines with
|
||
<code>sizeof(long)==4</code> try adding <code>#define long long long</code> …</li>
|
||
<li>The entry assumes the X11 displays default visual has 24 bit depth (RGB).</li>
|
||
<li>The entry assumes little endianness (in only one place though! If you have
|
||
PowerPC you can try and find that place to make it work), but more than this it
|
||
assumes unaligned loads of 64 bits <code>long</code>s are supported, i.e. it assumes that a
|
||
<code>long</code> can be loaded from any address that could hold an <code>int</code> otherwise. On non
|
||
antiquated X86 you’ll be fine.</li>
|
||
<li>The entry heavily relies on bitwise arithmetic (you don’t say!).</li>
|
||
</ul>
|
||
<h3 id="limitations">Limitations:</h3>
|
||
<p>Foremost the entry is very strict, unsafe and picky regarding its input.
|
||
Anything straying from the standard Golly macrocell legal format will result in
|
||
undefined behavior, meaning mostly a very defined core dump. Since
|
||
aforementioned core is rather large by default (about 4GG) it is highly
|
||
recommended to set the core dump size limit to 0 in the shell before playing
|
||
with fire …</p>
|
||
<p>This entry needs quite a lot of memory to be effective, but by modern standards
|
||
that is not too much. It does not do any garbage collection, so sooner or later
|
||
memory will run out, resulting, surprise, surprise, in a core dump. On the plus
|
||
side, this enables the nice time reversal feature… Anyway the amount of memory
|
||
used can be controlled by the Makefile <code>-DZ=...</code> argument. With the default <code>Z</code>,
|
||
the program will support in total about 240 million 64bit <code>long</code>s for the internal
|
||
memory, which should be sufficient for about 100 million nodes+leafs, as each
|
||
node is 3 <code>long</code>s and each leaf is 2.</p>
|
||
<p><em>Important:</em> Makefile <code>Z</code> define must be a power of two!</p>
|
||
<p>Zooming out past about S58 scale will enter a buggy twilight zone as only <code>long</code>
|
||
integers are used in the drawing code. Reverting to <code>double</code>s could have remedied
|
||
that, but then I’d need to use a lot of <code>ldexp()</code>s which would take the program
|
||
over the size limit. Also the program will crash once the universe goes past
|
||
level 64, though this is simply fixed by modifying a single constant in the
|
||
program, can you find it ? Anyway <code>2^58</code> squared is quite a big enough universe
|
||
for such a tiny program to simulate, no ?</p>
|
||
<p>In case cell memory did not run out, or your pattern did not grow too big, and
|
||
you have had patience enough and did not increase speed too much, you can run
|
||
out of the history buffer after <code>33333</code> steps.</p>
|
||
<p>If all of the above did not happen and result in the expected core dump, you
|
||
will encounter the final limitation, which is the absence of an escape key. Just
|
||
close the window or use <code>^C</code>/intr to exit ….</p>
|
||
<h3 id="warnings">Warnings</h3>
|
||
<p>Oh don’t get me started on the torrent of litanies gcc emits when used with
|
||
<code>-Wall</code>! Does it think I have not memorized by heart C’s precious operator
|
||
precedence table (or at least have a cheat sheet nearby) that it dares suggest
|
||
extra parentheses that would take the program over the limit ? And what if I do
|
||
not use a variable here or there, do I have to pay extra tax for every orphaned
|
||
variable?</p>
|
||
<p>There is the reasonable warning about some <code>long</code>s printed as <code>int</code>s but its OK too,
|
||
trust me.</p>
|
||
<p>Then there’s the warning about <code>gets(3)</code> being unsafe, which is indeed the only one
|
||
that appears by default in some versions of gcc linker. Yes Virginia, I know it
|
||
is unsafe, and I would not recommend anyone using this entry as part of a web
|
||
daemon, or a spaceship, no, seriously don’ do that.</p>
|
||
<h3 id="obfuscations">Obfuscations:</h3>
|
||
<p>Well almost none of the obfuscations are done on purpose, but mostly out of
|
||
necessity, so all identifiers possible to be one character, are, and they are
|
||
mercilessly reused. In the <code>main()</code> function there’s even a nice little
|
||
identifier first used as a global and then reused (shadowed) in the <em>same</em>
|
||
scope, and this did not produce even a little squeak of a warning from the
|
||
compiler! Macro compression is rather sparingly used, however magic numbers
|
||
abound everywhere, and bit twiddling is magical too. Do you know for example why
|
||
we have <code>unsigned F=-1</code> ? (No warning there of course :) Hint: Later in the
|
||
program you have <code>F/=17</code>. Did that make any sense? Further hint: print the
|
||
resulting <code>F</code> in hexadecimal…</p>
|
||
<p>And yes, the layout hint involves a mix of the most trendy typographical
|
||
character juxtaposed against a very ancient one, not to mention the program
|
||
includes some famous name dropping and documents itself as usual.</p>
|
||
<h3 id="special-thanks">Special thanks:</h3>
|
||
<p>To Tom Rockiki, the original co-writer of Golly, a personal friend and hashlife
|
||
master, who reviewed some earlier versions of the entry and freely shared some
|
||
of his vast knowledge regarding GOL programming and hashlife. As a free bonus,
|
||
Tom has allowed me to show his code which is probably the most efficient yet
|
||
most obfuscated way of calculating the GOL function on a 64 bits <code>8*8</code> leaf:</p>
|
||
<pre><code> unsigned long life8x8(long a) { unsigned long aw = a << 1, ae = a >> 1, s0 = aw
|
||
^ ae, s1 = aw & ae, hs0 = s0 ^ a, hs1 = (s0 & a) | s1, hs0w8 = hs0 >> 8, hs0e8 =
|
||
hs0 << 8, hs1w8 = hs1 >> 8, hs1e8 = hs1 << 8, ts0 = hs0w8 ^ hs0e8, ts1 = (hs0w8
|
||
& hs0e8) | (ts0 & s0); return (hs1w8 ^ hs1e8 ^ ts1 ^ s1) & ((hs1w8 | hs1e8) ^
|
||
(ts1 | s1)) & ((ts0 ^ s0) | a); }</code></pre>
|
||
<p>This uses only 19 bitwise operations and six shifts to calculate the inner 6x6
|
||
next generation bits of the input 8x8 !</p>
|
||
<h3 id="notice-to-those-who-wish-for-a-greater-challenge">NOTICE to those who wish for a greater challenge:</h3>
|
||
<p><strong>If you want a greater challenge, don’t read any further</strong>:
|
||
just try to understand the program via the source.</p>
|
||
<p>If you get stuck, come back and read below for additional hints and information.</p>
|
||
<h3 id="further-information-engineering-and-obfuscation-galore">Further information, engineering, and obfuscation galore:</h3>
|
||
<p>Those wait for you, curious and intrepid reader, in the attached
|
||
<a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/apholife.c">apholife.c</a> file, which is a partially obfuscated version of the
|
||
program I wrote with a lot of helpful annotations and comments for myself and
|
||
posterity, revealing some of the magic under the hood. This program is also a
|
||
somewhat improved version which uses <code>ldexp()</code>s in the draw routine and has
|
||
bigger constants, so it can zoom up to level 1024 if memory allows, and it tries
|
||
its best to avoid dumping core on the poor user when its memory runs out, rather
|
||
it enters freeze mode where you can still travel in calculated frozen
|
||
space-time. Well, it’s not nice and tame, it even has an escape key, usage
|
||
message, and to top it all it even avoids <code>gets(3)</code>!</p>
|
||
<!--
|
||
|
||
Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
|
||
|
||
You are free to share and adapt this file under the terms of this license:
|
||
|
||
Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
|
||
|
||
For more information, see:
|
||
|
||
https://creativecommons.org/licenses/by-sa/4.0/
|
||
|
||
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|
||
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|
||
|
||
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|
||
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|
||
|
||
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|
||
|
||
<div id="inventory">
|
||
<h1 id="inventory-for-2019dogon">Inventory for 2019/dogon</h1>
|
||
</div>
|
||
<h2 id="primary-files">Primary files</h2>
|
||
<ul>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/prog.c">prog.c</a> - entry source code</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/Makefile">Makefile</a> - entry Makefile</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/prog.orig.c">prog.orig.c</a> - original source code</li>
|
||
<li><a href="glider.mc">glider.mc</a> - Golly macrocell input file</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/gotts-dots.mc">gotts-dots.mc</a> - Golly macrocell input file</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/infinite_10cell.mc">infinite_10cell.mc</a> - Golly macrocell input file</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/infinite_5x5.mc">infinite_5x5.mc</a> - Golly macrocell input file</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/infinite.mc">infinite.mc</a> - Golly macrocell input file</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/infinite_minimal.mc">infinite_minimal.mc</a> - Golly macrocell input file</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/jagged.mc">jagged.mc</a> - Golly macrocell input file</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/message.mc">message.mc</a> - Golly macrocell input file</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/metacatacryst.mc">metacatacryst.mc</a> - Golly macrocell input file</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/metapixel-parity64.mc">metapixel-parity64.mc</a> - Golly macrocell input file</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/mosquito5.mc">mosquito5.mc</a> - Golly macrocell input file</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/try.sh">try.sh</a> - script to try entry</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/unlimited-novelty.mc">unlimited-novelty.mc</a> - Golly macrocell input file</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/apholife.c">apholife.c</a> - partially obfuscated 64-bit Hash Life source code</li>
|
||
</ul>
|
||
<h2 id="secondary-files">Secondary files</h2>
|
||
<ul>
|
||
<li><a href="2019_dogon.tar.bz2">2019_dogon.tar.bz2</a> - download entry tarball</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/README.md">README.md</a> - markdown source for this web page</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/.entry.json">.entry.json</a> - entry summary and manifest in JSON</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/.gitignore">.gitignore</a> - list of files that should not be committed under git</li>
|
||
<li><a href="https://github.com/ioccc-src/winner/blob/master/2019/dogon/.path">.path</a> - directory path from top level directory</li>
|
||
<li><a href="index.html">index.html</a> - this web page</li>
|
||
</ul>
|
||
<hr style="width:10%;text-align:left;margin-left:0">
|
||
<h4>
|
||
Jump to: <a href="#">top</a>
|
||
</h4>
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<!--
|
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|
||
Copyright © 1984-2025 by Landon Curt Noll. All Rights Reserved.
|
||
|
||
You are free to share and adapt this file under the terms of this license:
|
||
|
||
Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
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|
||
For more information, see:
|
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|
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||
|
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-->
|
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<div class="footer">
|
||
|
||
<div id="copyright"><h3>Copyright © 1984-2025 by Landon Curt Noll:
|
||
<a href="https://creativecommons.org/faq/#what-does-some-rights-reserved-mean"
|
||
target="_blank"
|
||
rel="license noopener noreferrer">Some Rights Reserved</a></h3>
|
||
<p>
|
||
This work is <b>licensed by Landon Curt Noll</b> under
|
||
<b><a href="https://creativecommons.org/licenses/by-sa/4.0/?ref=chooser-v1"
|
||
target="_blank"
|
||
rel="license noopener noreferrer"
|
||
style="display:inline-block;">CC BY-SA 4.0</a></b>.
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<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
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|
||
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<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
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|
||
You should <b>carefully review</b> the
|
||
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|
||
target="_blank"
|
||
rel="license noopener noreferrer">CC BY-SA 4.0 LEGAL CODE</a></b>
|
||
before using the licensed material.<br>
|
||
You may wish to review the
|
||
<b><a href="../../license.html"
|
||
target="_blank"
|
||
rel="license noopener noreferrer">highlights of some of the key features and terms</a></b>
|
||
of <b>CC BY-SA 4.0</b>.<br>
|
||
</p>
|
||
</div>
|
||
|
||
<div id="coda"><h3>Coda</h3>
|
||
<p>
|
||
<a href="https://validator.w3.org/nu/?doc=https%3A%2F%2Fwww.ioccc.org%2F2019%2Fdogon%2Findex.html" rel="nofollow">Nu HTML check this web page</a><br>
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<a href="#top">Jump to top</a> <a href="#content">Jump to Content</a> <a href="#inventory">Jump to Inventory</a><br>
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