Files
Landon Curt Noll a1c86c8a7a add original C links to entry navigation bars
The navigation bar for a winning entry now has a "_Original C_" link
(between the ✅ and the Inventory on the right hand side) so that one
may easily view the original C code that was submitted for IOCCC judging.

Ran `make www timestamp` to perform the above.
2025-08-10 12:46:23 -07:00

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<h1>The International Obfuscated C Code Contest</h1>
<h2>2006/grothe - Most obfuscated audio</h2>
<h3>Plays audio using a monitor</h3>
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<div class="navbar">
<a class="Left" href="../borsanyi/index.html">&larr; 2006/borsanyi</a>
<a class="Left" href="../index.html">&uarr; 2006 &uarr;</a>
<a class="Left" href="../hamre/index.html">2006/hamre &rarr;</a>
<a class="Right" href="https://github.com/ioccc-src/winner/blob/master/2006/grothe/grothe.c">C code</a>
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<h2 id="author">Author:</h2>
<ul>
<li>Name: <a href="../../authors.html#Aaron_Grothe">Aaron Grothe</a><br>
Location: <a href="../../location.html#US">US</a> - <em>United States of America</em> (<em>United States</em>)</li>
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<h2 id="to-build">To build:</h2>
<pre><code> make</code></pre>
<p><strong>NOTE</strong>: this entry requires the <code>X11/Xlib.h</code> header file and the X11 library to
compile. For more information see the
FAQ on “<a href="../../faq.html#X11">X11</a>”.</p>
<h2 id="to-use">To use:</h2>
<pre><code> ./grothe carrier_freq pixelclock horizontal_total &lt; some_input.txt</code></pre>
<h2 id="try">Try:</h2>
<p>Put on your “electronic ears” and then try:</p>
<pre><code> ./try.sh</code></pre>
<p>You may find using
a tunable scanning electronic ear helps.</p>
<h2 id="judges-remarks">Judges’ remarks:</h2>
<p>Most of the time, interference is annoying. This entry is the
exception that proves the rule. What is a bug to some is a
feature to this entry. :-)</p>
<h2 id="authors-remarks">Author’s remarks:</h2>
<p>The program draws patterns on the screen that can be picked up by a
<a href="https://en.wikipedia.org/wiki/Shortwave_radio">shortwave radio</a>. It emulates
the frequencies for an old fashion touch tone phone, so old songs can be played
by hitting <code>0-9</code>,<code>#</code>, and <code>*</code>.</p>
<p>To be able to run the program you need to determine the following
parameters:</p>
<ul>
<li><code>carrier_freq</code>
<ul>
<li>base frequency used to host music</li>
</ul></li>
<li><code>pixelclock</code>
<ul>
<li>refresh rate of the monitor</li>
</ul></li>
<li><code>horizontal_total</code>
<ul>
<li>total scan along the horizontal axis</li>
</ul></li>
</ul>
<p>If you have <code>xvidtune</code> installed you can get the <code>pixelclock</code> and
<code>horizontal_total</code> with the following command</p>
<pre><code> xvidtune -show | head -n 1 | awk &#39;{ print &quot;pixelclock &quot; $2 * 1000000 &quot; horizontal_total = &quot; $6 }&#39;</code></pre>
<p>Example from my laptops:</p>
<pre><code> ./grothe 65000000 10000000 1344 &lt; twinkle.txt</code></pre>
<p>Even if the user gets a setting off, the sound will usually be able to be
heard on <a href="https://en.wikipedia.org/wiki/AM_broadcasting">AM</a> at a multiple of
the original frequency.</p>
<p>The core idea of using a machine to play music on AM radio goes all the
way back to the <a href="https://en.wikipedia.org/wiki/Altair_8800">Altair computers</a>
and <a href="https://en.wikipedia.org/wiki/ZX81">Timex Sinclair ZX-81</a>s.</p>
<h3 id="several-example-songs">Several example songs</h3>
<p>Olympics Fanfare - from <code>antang@phakt.usc.edu</code> - Tony:</p>
<pre><code> 4-9-91231,2222-321123123-9-91231,2222-32112321</code></pre>
<p>Twinkle Twinkle Little Star - from <code>fsufunkyb@aol.com</code> - Ben Schmidt:</p>
<pre><code> 1199##9-6633221-9966332-9966332-1199#9-6633221-</code></pre>
<p>Generic Arabian Tune - from <code>rdippold@qualcomm.com</code> - Ron “Asbestos” Dippold:</p>
<pre><code> 453,54,4569564459,9#95458,8987453 54</code></pre>
<p>Others can be found by doing a search for “touch tone phone songs”.</p>
<h3 id="obfuscations">Obfuscations</h3>
<ul>
<li>Some numbers expressed in Octal, some in hex and some in decimal:</li>
</ul>
<blockquote>
<p>“A foolish consistency is the hobgoblin of little minds.” - Ralph Waldo
Emerson.</p>
</blockquote>
<ul>
<li>Funky scoping, looking at the nanosleep section and <code>XsetWindowAttributes</code>
declares local variables.</li>
<li>Algorithm is very weird, uses <code>y</code> dimension to draw carrier frequency
and <code>x</code> dimension to draw audio frequency, based on <a href="http://www.erikyyy.de">Erik
Thiele</a>’s
<a href="http://www.erikyyy.de/tempest/">Tempest for Eliza</a>.</li>
<li>lack of <code>#define</code>s confuses many people :-)</li>
<li>figuring out your <code>pixelclock</code> and <code>horizontal_total</code> and which <code>carrier_freq</code>
to use can be an exercise in obfuscation for the user.</li>
<li>use of commas in various places, confuses most C code beautifiers
sometimes making the beautified code harder to read</li>
<li>use of <code>static</code> to ensure initialization is EVIL and done in several
places</li>
<li>uses <code>static</code> declarations &amp; <code>void</code> function returns we don’t care about
making the code harder to read.</li>
<li>does sound using only <a href="https://en.wikipedia.org/wiki/Xlib">X11 libs</a>, no other
libs required.</li>
<li>demonstrates tempest emissions in a fun/easy way.</li>
<li>follows good programming practices of actually setting exit codes and giving
usage when run with incorrect parameters.</li>
</ul>
<h3 id="references">References</h3>
<p><a href="http://www.erikyyy.de/tempest/">Tempest for Eliza - Basis for Algorithms</a>.</p>
<p><a href="https://web.archive.org/web/20070612152538if_/http://silcnet.org/priikone/programs/tempest-AM-1.0.tar.gz">Tempest
AM</a>
- Another early program in this field. See
<a href="https://web.archive.org/web/20070612152538/http://silcnet.org/priikone/programs.php?lang=en">here</a>
for a bit more information on the program (search for <code>Tempest-AM Radio Signal Transmitter</code>).</p>
<p>The paper
<a href="https://www.cl.cam.ac.uk/~mgk25/ih98-tempest.pdf">Soft Tempest: Hidden Data Transmission Using Electromagnetic
Emanations</a> by Markus G.
Kuhn’s and Ross J. Anderson’s.</p>
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<h2 id="primary-files">Primary files</h2>
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<li><a href="olympic.txt">olympic.txt</a> - sample input</li>
<li><a href="test.txt">test.txt</a> - sample input</li>
<li><a href="https://github.com/ioccc-src/winner/blob/master/2006/grothe/try.sh">try.sh</a> - script to try entry</li>
<li><a href="twinkle.txt">twinkle.txt</a> - sample input</li>
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