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323 lines
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<title>1991/fine - Best One Liner</title>
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<meta name="description" content="1991 IOCCC entry fine - Best One Liner">
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<meta name="keywords" content="IOCCC, 1991, IOCCC 1991, IOCCC entry, fine, Best One Liner">
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<div class="header">
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<img src="../../png/ioccc.png" alt="IOCCC image by Matt Zucker" width=300 height=110>
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<h1>The International Obfuscated C Code Contest</h1>
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<h2>1991/fine - Best One Liner</h2>
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<a class="Left" href="../dds/index.html">← dds</a>
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<a class="Left" href="../index.html">↑ 1991 ↑</a>
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<a class="Left" href="../rince/index.html">rince →</a>
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<a class="Right" href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1991/fine/fine.c">C code</a>
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<a class="Right" href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1991/fine/Makefile">Makefile</a>
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<a href="../../index.html">IOCCC Home</a>
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<h2 id="author"><a name="author"></a>Author:</h2>
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<ul>
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<li>Name: <a href="../../authors.html#Thomas_A_Fine">Thomas A. Fine</a><br>
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Location: <a href="../../location.html#US">US</a> - <em>United States of America</em> (<em>United States</em>)</li>
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</ul>
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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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<h2 id="to-use">To use:</h2>
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<pre><code> echo text | ./fine</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 read the last line backwards! Credit goes to <a href="../../authors.html#Brian_Westley">Merlyn LeRoy (Brian
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Westley)</a> for that. See his 22 August 1992
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<a href="https://groups.google.com/g/rec.puzzles/c/z_xVPMRVBtg/m/lyEYSAeBD4gJ">rec.puzzles
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post</a>.
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Some others come from his 1989 entry as well. To
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those who have a harder time reading backwards it says: <code>Gary lent the rug</code>,
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rotated from <code>the rug gary lent</code>!</p>
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<h2 id="judges-remarks">Judges’ remarks:</h2>
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<p>This filter, 80 chars plus a newline, fits into a single line on most
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terminals (unless your terminal has a line wrap mis-feature :-)).</p>
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<p>Note in 2023: fixing this entry to work with modern systems increased the size,
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originally to 106 characters but it was dropped back down to 80 with clever use
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of the Makefile.</p>
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<p>This entry is likely one of the smallest C implementations of this
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filter, excluding programs that resort to command line or include
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file tricks.</p>
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<p>How does this program work? Which 3 bytes of C code can be changed
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into 2 bytes, allowing the program to still work, but also stripping
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the high bit off some input?</p>
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<h2 id="authors-remarks">Author’s remarks:</h2>
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<p>The author wishes to thank J Greely for the last 6 bytes.</p>
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<p>Here’s about how it does it:</p>
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<p>NOTE: Bits are referred to as 76543210, high to low.</p>
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<ol type="1">
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<li><p>Get the character in variable <code>a</code>. Note the fun way we check for <code>EOF</code>.
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(thanks J).</p></li>
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<li><p>Reverse bit 6, and strip bit 5. Bit 6 determines (mostly) whether
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or not this character is a letter. Bit 5 would determine case if
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we cared. Assign this value to variable <code>b</code> (We need to save it,
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since we need to make 2 comparisons and maybe one operation with
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this value). We can’t abuse our first variable, since it saves the
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bits we’re changing.</p></li>
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<li><p>Check this value to see if it is a letter. It must be non-zero -
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if it is zero, then we have either the <code>@</code> (64) or the
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<code>`</code> (96). It also must be less than 27 - this checks the
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range for letters as well as implicitly checking the value of bit 6
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(if it was originally clear, it is set now, so <code>b</code> would be too big).</p></li>
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<li><p>If it is not a letter, the conditional expression inside of the
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<code>putchar()</code> returns the original character (<code>a</code>). Otherwise, it
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returns a really messy expression that performs the actual rotation
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and fixes the fifth and sixth bits:</p>
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<ul>
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<li><ol type="A">
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<li>Subtract 1, to get into the range 0-25 (for the modulo operation).</li>
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</ol></li>
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<li><ol start="2" type="A">
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<li>Add 13 to the character. Steps A and B are combined.</li>
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</ol></li>
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<li><ol start="3" type="A">
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<li>Take this modulo 26 to make the addition wrap around.</li>
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</ol></li>
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<li><ol start="4" type="A">
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<li>Fix bits 5 and 6, based on variable <code>a</code>.</li>
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</ol></li>
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<li><ol start="5" type="A">
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<li>Add 1 back in (we took it out in step A.) This is okay to do <em>after</em>
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step D, because we know the addition won’t trickle up past the fourth bit
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(<code>b</code> would have to be 31 for this to happen).</li>
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</ol></li>
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</ul></li>
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</ol>
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<p>Notice that this implementation operates only on characters with the
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high bit clear. The high bit can be ignored without changing the size
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of the program. Also, if you know you are only dealing with seven bit
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data, the size can be reduced by one byte. These are left as exercises
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for the student.</p>
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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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https://creativecommons.org/licenses/by-sa/4.0/
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-->
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<h1 id="inventory-for-1991fine"><a name="inventory"></a>Inventory for 1991/fine</h1>
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<p><a href="#top">Jump to top</a></p>
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<h2 id="primary-files">Primary files</h2>
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<ul>
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<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1991/fine/fine.c">fine.c</a> - entry source</li>
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<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1991/fine/Makefile">Makefile</a> - entry Makefile</li>
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<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1991/fine/fine.orig.c">fine.orig.c</a> - original source</li>
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<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1991/fine/try.sh">try.sh</a> - how to run</li>
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</ul>
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<h2 id="secondary-files">Secondary files</h2>
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<ul>
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<li><a href="1991_fine.tar.bz2">1991_fine.tar.bz2</a> - download entry tarball</li>
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<li><a href="index.html">index.html</a> - this web page</li>
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||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1991/fine/README.md">README.md</a> - markdown source for this web page</li>
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||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1991/fine/.entry.json">.entry.json</a> - description of entry in JSON</li>
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||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1991/fine/.gitignore">.gitignore</a> - list of files that should not be committed under git</li>
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||
<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1991/fine/.path">.path</a> - directory path from top directory</li>
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||
</ul>
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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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https://creativecommons.org/licenses/by-sa/4.0/
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-->
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<div class="footer">
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<h2><a name="copyright"></a>Copyright and CC BY-SA 4.0 License</h2>
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<p>All IOCCC content including this file and web page are:</p>
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<b> Copyright © 1984-2024 by Landon Curt Noll. <a href="https://creativecommons.org/faq/#what-does-some-rights-reserved-mean">Some Rights Reserved</a>.</b>
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<p>This work is licensed by Landon Curt Noll under:</p>
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<p xmlns:cc="http://creativecommons.org/ns#" ><b><a href="https://creativecommons.org/licenses/by-sa/4.0/?ref=chooser-v1"
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target="_blank" rel="license noopener noreferrer" style="display:inline-block;"> CC BY-SA 4.0
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src="../../png/cc.png"
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</a></b></p>
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<p>The <b>CC BY-SA 4.0 LEGAL CODE</b> for this license is found under:</p>
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<p>You should <b>carefully review</b> all of the terms and conditions of the
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before using the licensed material.</p>
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<p>You may wish to review the <b><a href="../../license.html">highlights of some of the key
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features and terms</a></b> of the <a href="https://creativecommons.org/licenses/by-sa/4.0/legalcode.en">actual license</a>.</p>
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<h2>Coda</h2>
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<p><a href="https://validator.w3.org/nu/?doc=https%3A%2F%2Fioccc-src.github.io%2Ftemp-test-ioccc%2F1991%2Ffine%2Findex.html">Nu HTML check this web page</a></p>
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<p><a href="#top">Jump to top</a> <a href="#content">Jump to Content</a> <a href="#inventory">Jump to Inventory</a></p>
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