We add an initial "_title_" and "_abstract_" to all entry `.entry.json` files. The `bin/csv2entry.sh` tool reads the `summary.csv` file and loads the "_title_" and "_abstract_" to entry `.entry.json` files. Changed `bin/csv2entry.sh` VERSION from "1.3 2024-09-23" to "1.4 2024-09-27". Perform `make csv2entry` to perform the above and test under macOS. The `bin/cvt-submission.sh` tool adds "_title_" and "_abstract_" to the .entry.json based on the `.info.json` file. Changed `bin/cvt-submission.sh` VERSION from "1.2 2024-09-23" to "1.3 2024-09-27". The `bin/entry2csv.sh` tool forms the `summary.csv` file based on the "_title_" and "_abstract_" fields found in .entry.json files. Changed `bin/entry2csv.sh` VERSION from "1.3 2024-09-23" to "1.4 2024-09-27". Perform `make entry2csv` to perform the above and test under macOS. Added `-H` and `header=with-header-3` to the `bin/md2html.cfg` for the configuration entry for `[12][0-9][0-9][0-9]/*/README.md`. Changed `bin/md2html.sh` VERSION from "1.6 2024-08-17" to "1.7 2024-09-27". All entry `index.html` files now list the "_abstract_" in a new `<h3>abstract</h3>` header. Changed `bin/subst.entry-index.sh` VERSION from "1.6 2024-09-23" to "1.7 2024-09-27". Removed `summary.csv`. Added `summary.csv` and `summary.numbers` to `.gitignore`. Sorted the result with `bin/sgi.sh`. Perform `make quick_www` to perform the above and test under macOS. Perform `make www` to perform the above and test under macOS.
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<img src="../../png/ioccc.png"
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width=300
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height=110>
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||
</a>
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||
<h1>The International Obfuscated C Code Contest</h1>
|
||
<h2>2000/rince - Astronomically obfuscated</h2>
|
||
<h3>Plots the positions of the four Galilean moons of Jupiter</h3>
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</div>
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<!-- END: this line ends content from: inc/header.default.html -->
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<!-- START: this line starts content from: inc/navbar.mid.html -->
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<div class="navbar">
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<a class="Left" href="../primenum/index.html">← 2000/primenum</a>
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<a class="Left" href="../index.html">↑ 2000 ↑</a>
|
||
<a class="Left" href="../robison/index.html">2000/robison →</a>
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<a class="Right" href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/rince/rince.c">C code</a>
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<a class="Right" href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/rince/Makefile">Makefile</a>
|
||
<a class="Right" href="#inventory">Inventory</a>
|
||
<a class="Right" href="https://validator.w3.org/nu/?doc=https%3A%2F%2Fioccc-src.github.io%2Ftemp-test-ioccc%2F2000%2Frince%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#James_Bonfield">James Bonfield</a><br>
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Location: <a href="../../location.html#GB">GB</a> - <em>United Kingdom of Great Britain and Northern Ireland</em> (<em>United Kingdom</em>)</li>
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</ul>
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<!-- BEFORE: 1st line of markdown file: 2000/rince/README.md -->
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<h2 id="to-build">To build:</h2>
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<pre><code> make all</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>
|
||
<h3 id="bugs-and-misfeatures">Bugs and (Mis)features:</h3>
|
||
<p>The current status of this entry is:</p>
|
||
<blockquote>
|
||
<p><strong>STATUS: INABIAF - please DO NOT fix</strong></p>
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||
</blockquote>
|
||
<p>For more detailed information see <a href="../../bugs.html#2000_rince">2000/rince in bugs.html</a>.</p>
|
||
<h2 id="to-use">To use:</h2>
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<pre><code> ./rince number number2</code></pre>
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<p>If <code>DISPLAY</code> is not set the program will very likely crash or do something
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different.</p>
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<h2 id="try">Try:</h2>
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<pre><code> ./try.sh</code></pre>
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<p>This will run the program several times with different parameters to show
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different types of things. See the author’s remarks for more details.</p>
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<h2 id="judges-remarks">Judges’ remarks:</h2>
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<p>This program may have you going around in circles :-) Try running it first
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before reading the author’s remarks below.</p>
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<p>The judges verified the correctness of output for recent dates through visual
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observation.</p>
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<h2 id="authors-remarks">Author’s remarks:</h2>
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<h3 id="how-to-use-it">How to use it</h3>
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<p>The simplest way to run it is with no arguments. Just type:</p>
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<pre><code> ./rince</code></pre>
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<p>You will need to have access to X windows, although it doesn’t require
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desperately high resolution and there are no known limitations on colour
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depth.</p>
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<p>The display will change slowly over time, although it may take 10 minutes
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or more to be visible. For those that cannot wait that long the program
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has a built in time machine. Indeed the program knows the speed of light,
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which is used to ensure that we see the “live” pictures. Simply specify
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the fraction of a day to skip forward for each screen refresh. I suggest:</p>
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<pre><code> ./rince 0.01</code></pre>
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<p>To display the output (still guessing?) for a given date, specify two
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arguments. The first argument is as before and the second argument is a
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Julian day number (given as a fractional component). E.g.:</p>
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<pre><code> ./rince 0 2441193.6
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./rince 0.01 2441193.6</code></pre>
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<p>A Julian day is defined to be the number of days since January 1st in the year
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<code>-4712 (4713BC)</code>, starting at 12 noon GMT.<a href="#fn1" class="footnote-ref" id="fnref1" role="doc-noteref"><sup>1</sup></a><a href="#fn2" class="footnote-ref" id="fnref2" role="doc-noteref"><sup>2</sup></a> To aid conversion from our time
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(GMT) to Julian day there is a supplementary program named:
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<a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/rince/dmy2jd.c">dmy2jd.c</a>. Run it with <code>day_float month year</code> as arguments. See below
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for an example.</p>
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<h3 id="what-it-does">What it does</h3>
|
||
<p>This program plots the positions of the four <a href="https://en.wikipedia.org/wiki/Galilean_moons">Galilean
|
||
moons</a> of
|
||
<a href="https://science.nasa.gov/jupiter/">Jupiter</a>, as seen from
|
||
<a href="https://science.nasa.gov/earth/">Earth</a>. It doesn’t correct for your
|
||
location on Earth, but I assure you that the
|
||
<a href="https://en.wikipedia.org/wiki/Parallax#Astronomy">parallax</a> is minimal!</p>
|
||
<p>The moons are labelled with Roman numerals from <code>I</code> to <code>IV</code>, <code>I</code> being the
|
||
closest to the planet and <code>IV</code> being the furthest. They are:</p>
|
||
<ul>
|
||
<li><code>I</code>
|
||
<ul>
|
||
<li><a href="https://science.nasa.gov/jupiter/moons/io">Io</a></li>
|
||
</ul></li>
|
||
<li><code>II</code>
|
||
<ul>
|
||
<li><a href="https://science.nasa.gov/jupiter/moons/europa/">Europa</a></li>
|
||
</ul></li>
|
||
<li><code>III</code>
|
||
<ul>
|
||
<li><a href="https://science.nasa.gov/jupiter/moons/ganymede/">Ganymede</a></li>
|
||
</ul></li>
|
||
<li><code>IV</code>
|
||
<ul>
|
||
<li><a href="https://science.nasa.gov/jupiter/moons/callisto">Callisto</a></li>
|
||
</ul></li>
|
||
</ul>
|
||
<p>Amazingly, all it takes is a pair of binoculars to see the Galilean moons,
|
||
so the results can be experimentally checked. (Note that at present, the
|
||
best views of Jupiter are over the autumn/winter.)</p>
|
||
<p>The positions of the moons should be correct for binoculars, but possibly
|
||
not if you have a telescope or if you are in the southern hemisphere. In
|
||
that case I suggest that to get the correct image you look at the screen
|
||
from inside the monitor whilst standing on your head. In case of
|
||
confusion, please consult the following chart (*):</p>
|
||
<pre><code> N
|
||
^
|
||
|
|
||
E <---+---> W
|
||
|
|
||
v
|
||
S</code></pre>
|
||
<p>(*) Not to scale.</p>
|
||
<h3 id="history">History</h3>
|
||
<p>Galileo discovered the moons in January 1610.
|
||
<a href="https://web.archive.org/web/20001204212000/http://www-isds.jpl.nasa.gov/cwo/cwo_54ga/html/cd/galileo.htm" class="uri">https://web.archive.org/web/20001204212000/http://www-isds.jpl.nasa.gov/cwo/cwo_54ga/html/cd/galileo.htm</a>
|
||
states the following:</p>
|
||
<blockquote>
|
||
<p>By early 1610, Galileo had further improved his telescope by double its power,
|
||
so it now enlarged objects a thousand times. He began looking at the stars and
|
||
couldn’t believe how many more he could now see! The number seemed infinite. He
|
||
was beginning to realize the fixed stars weren’t a flat distant wall on a globe,
|
||
but a three-dimensional expanse bigger than anyone had ever thought!</p>
|
||
<p>Then, on January 7, about an hour after sunset, Jupiter rose in the east,
|
||
and Galileo happened to turn his powerful scope on its bright disk. It wasn’t
|
||
the first time he had looked at Jupiter, but before it was with one of his
|
||
lesser-powered telescopes. This time, though, he noticed three small but bright
|
||
stars near the planet, two to one side and one to the other. He wondered at how
|
||
bright the small stars were and how they were arranged in what seemed like a
|
||
straight line. The next night he decided to look at Jupiter again, and to his
|
||
surprise, the stars had moved. But not in such a way as he would expect. If
|
||
Jupiter was moving as it normally should, the stars would be east of Jupiter.
|
||
But all three were to the west! The next night was cloudy, but on January 10,
|
||
Galileo was able to observe the planet again. One of the stars was gone, and the
|
||
other two were now on the east side. As the stars moved around Jupiter on each
|
||
succeeding night, and were finally joined by a fourth star, it dawned on Galileo
|
||
that what he had found were moons orbiting Jupiter! Almost at once he realized
|
||
that this was proof that not all objects orbited the Earth. Here were four
|
||
bodies that were orbiting Jupiter. One argument against the sun-centered theory
|
||
was, if the Earth orbited the sun, wouldn’t the moon get left behind? Here he
|
||
could see for himself that somehow, a planet could orbit the sun, and not leave
|
||
a moon behind!</p>
|
||
</blockquote>
|
||
<p>Thus we can plot Galileo’s discoveries using the following three plots:</p>
|
||
<pre><code> ./rince 0 $(./dmy2jd 7.8 1 1610)
|
||
./rince 0 $(./dmy2jd 8.8 1 1610)
|
||
./rince 0 $(./dmy2jd 10.8 1 1610)</code></pre>
|
||
<p>However we can go one better by seeing what Galileo would have seen if it
|
||
wasn’t cloudy on the 9th. Try:</p>
|
||
<pre><code> ./rince 0 $(./dmy2jd 9.85 1 1610)</code></pre>
|
||
<p>to see what he was missing out on. I wonder what he’d have made of that!</p>
|
||
<p>Galileo discovered the fourth moon a few days later.</p>
|
||
<p>I’ve tried typing these dates into two Java based Jovian moon plotters,
|
||
but both I tried had problems dealing with dates earlier than 1900. More
|
||
professional software, such as the
|
||
<a href="http://www.bmsoftware.com/skymappro9.htm">SkyMap</a> gets these values
|
||
correct and this compares well with the above description and with this
|
||
IOCCC entry.</p>
|
||
<p>The year 4713BC was chosen by <a href="https://en.wikipedia.org/wiki/Joseph_Justus_Scaliger">Joseph Justus
|
||
Scaliger</a> in the 16th
|
||
Century, so clearly this program has a long history :-) A more complete
|
||
description of the origins of Julian Days can be found at
|
||
<a href="https://web.archive.org/web/20001206152200/http://aa.usno.navy.mil/AA/faq/docs/millennium.html" class="uri">https://web.archive.org/web/20001206152200/http://aa.usno.navy.mil/AA/faq/docs/millennium.html</a>.</p>
|
||
<h3 id="assumptions">Assumptions</h3>
|
||
<p>This program assumes:</p>
|
||
<ol type="1">
|
||
<li><p>The ASCII character set is used.</p></li>
|
||
<li><p>That an enormous comet hasn’t changed the course of
|
||
<a href="https://science.nasa.gov/jupiter/">Jupiter</a> (or
|
||
<a href="https://science.nasa.gov/earth/">Earth</a>!).</p></li>
|
||
<li><p>That the date has not been specified as the gap between the
|
||
<a href="https://en.wikipedia.org/wiki/Julian_calendar">Julian</a> and
|
||
<a href="https://en.wikipedia.org/wiki/Gregorian_calendar">Gregorian</a> calendar.</p></li>
|
||
<li><p>That the <code>DISPLAY</code> environment variable is set and the X display can opened.
|
||
If this is not the case the program will crash.</p></li>
|
||
<li><p>There is a year 2000BC problem :-)</p>
|
||
<p>More specifically, the plots for dates that far back are too inaccurate to
|
||
be of realistic use. Comparisons against <a href="http://www.bmsoftware.com/skymappro9.htm">SkyMap
|
||
Pro</a> show that there is a good
|
||
similarity (but not much more) up to about 500BC.</p></li>
|
||
<li><p>The code definitely is not portable - it will produce incorrect results if
|
||
run from the surface of <a href="https://science.nasa.gov/mars/">Mars</a>.</p></li>
|
||
</ol>
|
||
<h3 id="obfuscations">Obfuscations</h3>
|
||
<p>In addition to the normal obfuscations, I feel that the code contains some less
|
||
common tricks. Taken through the standard rounds listed in the
|
||
<a href="../guidelines.txt">guidelines</a>, the code attempts to pass these as follows:</p>
|
||
<ol type="1">
|
||
<li><p>Look at the original source</p>
|
||
<p>With luck, pure casual inspection should not reveal much except
|
||
that the program contains the X Windows logo (a big clue) and
|
||
contains a date. This date may give a clue to a few people that
|
||
this is an astronomical program.</p>
|
||
<p>Unfortunately I was stretched for space which meant that the
|
||
large string constant could not be split up using a “partA”
|
||
“partB” method which clearly limits the code layout. However the
|
||
space saved by using a single long string constant is more than
|
||
outweighed by the ability to further obfuscate.</p></li>
|
||
<li><p>convert ANSI trigraphs to ASCII</p>
|
||
<p>These are not used.</p></li>
|
||
<li><p>C pre-process the source ignoring <code>#include</code> lines</p></li>
|
||
<li><p>C pre-process the source ignoring <code>#define</code> and <code>#include</code> lines</p>
|
||
<p>This does a good job of expanding out the code, but it does not
|
||
clarify things greatly. The use of <code>#define</code>s has been restricted
|
||
primarily to a space-saving mechanism.</p>
|
||
<p>Additionally, the use of <code>typedef</code>s means that the types used are
|
||
still obscured unless further replacement edits are made.</p></li>
|
||
<li><p>Run it through a C beautifier.</p>
|
||
<p>GNU <code>indent(1)</code> seems to do a reasonable job, provided that the
|
||
<code>#define</code>s are expanded first. This doesn’t lay the algorithm
|
||
particularly bare though as most of the obfuscations are not
|
||
simple code layouts.</p></li>
|
||
<li><p>Examine the algorithm.</p>
|
||
<p>The algorithm operates on two levels. The main visible level is
|
||
by taking a large string and breaking this down into a series of
|
||
opcodes (which I have termed J-code). These are then executed.</p>
|
||
<p>To get to the real method of how it works, you need to decode the opcode
|
||
string (which deliberately contains as many <code>;</code>, <code>{</code> and <code>}</code> symbols as
|
||
possible), which will give you a <a href="https://en.wikipedia.org/wiki/Reverse_Polish_notation">Reverse Polish
|
||
notation</a> chunk of
|
||
mathematics.</p>
|
||
<p>Sensible people amongst you will simply refer to the referenced book :-)</p></li>
|
||
<li><p>Lint it.</p>
|
||
<p>I no longer have lint, although I do have access to Purify. I’m
|
||
happy to say that purify does not detect any memory errors or
|
||
memory leaks.</p>
|
||
<p>See below for compilation warnings.</p></li>
|
||
<li><p>Compile it.</p>
|
||
<p>I’m sorry to say that there are several warnings issued by the
|
||
compiler.</p>
|
||
<p>Firstly, the return type for <code>X()</code> is not specified, so it defaults to <code>int</code>.
|
||
Horror of all horrors - this function does not return an integer type (it
|
||
doesn’t contain any specific <code>return</code>s). The return value from <code>X()</code> is not
|
||
accessed. The same problem occurs in <code>main()</code> - it does not return. However
|
||
<code>main()</code> never exits unless there is a serious error.</p>
|
||
<p>The 6th argument of <code>XDrawText</code> (which should be <code>XTextItem</code>) is
|
||
passed as a compatible structure, but without casting. This is
|
||
to reduce code space. A more elegant solution is to remove the
|
||
<code>struct {...} Z</code> completely and use <code>XTextItem f={i-127+r/3*2,r%3+r/3+1,0,E}</code> at the start of <code>XDrawText</code>
|
||
block. Although this is accepted by several compilers, it is not
|
||
strict ANSI due to the non-constant initialisers. A pity.</p>
|
||
<p>Note that I make use of <code>usleep()</code>. This is a POSIX call (it is BSD), but it’s
|
||
supported on many systems. It may be implemented using <code>select()</code> or <code>poll()</code> if
|
||
required, or as a final solution you can change the <code>usleep(10000)</code> to
|
||
<code>sleep(1)</code>. To compile on systems which do not have <code>usleep()</code>, but do have
|
||
<code>select()</code>, the following may suffice as an additional compiler argument:</p>
|
||
<pre><code> -Dusleep={time_t v[2]={0,10000};select(0,0,0,0,v);}</code></pre>
|
||
<p><code>gcc</code> complains about “unreachable code at beginning of switch
|
||
statement”, although removing some of this code will prevent
|
||
the algorithm from working.</p>
|
||
<p><code>gcc</code> also suggests that I should be using extra parenthesis, but
|
||
I’m taking this as good comment :-)</p></li>
|
||
</ol>
|
||
<p>In addition to the above, the program has the following useful(?)
|
||
obfuscations:</p>
|
||
<ol type="1">
|
||
<li><p>The algorithm requires many floating point numbers (about 50). These are
|
||
encoded as ASCII.</p></li>
|
||
<li><p>The J-code algorithm has opcodes designed to be space saving. They are all
|
||
one byte, but many are also considered as whitespace by the rules. This
|
||
algorithm forms part of the same string that the floating point constants are
|
||
embedded within. What does the <code>;</code> command do in J-code?</p></li>
|
||
<li><p>The J-code language is both stack based and variable based. This
|
||
“uncleanliness” is not ideal from a computer science angle, but when has
|
||
cleanliness been considered as good in IOCCC? :-)</p></li>
|
||
<li><p>Association of unconnected data by implied function usage. E.g. use of
|
||
<code>strlen()</code> and <code>sizeof()</code> simply to return useful numerical values, using
|
||
irrelevant arguments.</p></li>
|
||
<li><p>As we already have a dependency on ASCII this has been abused further.
|
||
Specifically some integer constants are specified as ASCII and some ASCII
|
||
constants are integers. This hides the true meaning for the values.</p></li>
|
||
<li><p>Red herrings: there are a couple of pieces of code whose appearance is just
|
||
there to mislead the infirm of mind. I’ve only tried to include such examples
|
||
in places where at first glance the code appears to be executed.</p></li>
|
||
</ol>
|
||
<h3 id="references">References</h3>
|
||
<!--
|
||
|
||
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/
|
||
|
||
-->
|
||
<!-- AFTER: last line of markdown file: 2000/rince/README.md -->
|
||
<hr style="width:10%;text-align:left;margin-left:0">
|
||
<section id="footnotes" class="footnotes footnotes-end-of-document" role="doc-endnotes">
|
||
<h5>Footnotes</h5>
|
||
<ol>
|
||
<li id="fn1"><p>Astronomical algorithms (1st ed): page 59
|
||
Jean Meeus. Published by Willmann-Bell Inc.<a href="#fnref1" class="footnote-back" role="doc-backlink">↩︎</a></p></li>
|
||
<li id="fn2"><p>Astronomical algorithms (1st ed): pages 285-299.
|
||
Jean Meeus. Published by Willmann-Bell Inc.<a href="#fnref2" class="footnote-back" role="doc-backlink">↩︎</a></p></li>
|
||
</ol>
|
||
</section>
|
||
|
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|
||
<div id="inventory">
|
||
<h1 id="inventory-for-2000rince">Inventory for 2000/rince</h1>
|
||
</div>
|
||
<h2 id="primary-files">Primary files</h2>
|
||
<ul>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/rince/rince.c">rince.c</a> - entry source code</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/rince/Makefile">Makefile</a> - entry Makefile</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/rince/rince.orig.c">rince.orig.c</a> - original source code</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/rince/try.sh">try.sh</a> - script to try entry</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/rince/dmy2jd.c">dmy2jd.c</a> - supplementary program source</li>
|
||
</ul>
|
||
<h2 id="secondary-files">Secondary files</h2>
|
||
<ul>
|
||
<li><a href="2000_rince.tar.bz2">2000_rince.tar.bz2</a> - download entry tarball</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/rince/README.md">README.md</a> - markdown source for this web page</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/rince/.entry.json">.entry.json</a> - entry summary and manifest in JSON</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/rince/.gitignore">.gitignore</a> - list of files that should not be committed under git</li>
|
||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/rince/.path">.path</a> - directory path from top level directory</li>
|
||
<li><a href="index.html">index.html</a> - this web page</li>
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</ul>
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<hr style="width:10%;text-align:left;margin-left:0">
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<h4>
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Jump to: <a href="#">top</a>
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<!--
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Copyright © 1984-2024 by Landon Curt Noll. 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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<div class="footer">
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<div id="copyright"><h3>Copyright © 1984-2024 by Landon Curt Noll:
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<a href="https://creativecommons.org/faq/#what-does-some-rights-reserved-mean"
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target="_blank"
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rel="license noopener noreferrer">Some Rights Reserved</a></h3>
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<p>
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This work is <b>licensed by Landon Curt Noll</b> under
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<b><a href="https://creativecommons.org/licenses/by-sa/4.0/?ref=chooser-v1"
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You should <b>carefully review</b> the
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rel="license noopener noreferrer">CC BY-SA 4.0 LEGAL CODE</a></b>
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before using the licensed material.<br>
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You may wish to review the
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<b><a href="../../license.html"
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rel="license noopener noreferrer">highlights of some of the key features and terms</a></b>
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</div>
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||
|
||
<div id="coda"><h3>Coda</h3>
|
||
<p>
|
||
<a href="https://validator.w3.org/nu/?doc=https%3A%2F%2Fioccc-src.github.io%2Ftemp-test-ioccc%2F2000%2Frince%2Findex.html" rel="nofollow">Nu HTML check this web page</a><br>
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