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Landon Curt Noll d414b6d71f add quick-readme2index.sh, improve all-run.sh and readme2index.sh 
Improved `all-run.sh` and `readme2index.sh` so that
certain command line options (e.g., -p, -P, -u, -U ...)
are only passed along to other tools if they are
given on the command line.

all-run.sh VERSION changed from "1.1.1 2024-01-19"
to "1.1.2 2024-01-20",

readme2index.sh VERSION changed from "1.1 2024-01-16"
to "1.1.1 2024-01-20".

Added `quick-readme2index.sh` that only calls
`readme2index.sh` if the `index.html` is not
a non-empty file, or of either `.winner.json`
and/or `README.md` is newer than `index.html`.

Updated all `index.html` files because the
the file contains a comment that includes
the newly modified readme2index.sh VERSION.
2024-01-21 00:21:40 -08:00

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<link rel="stylesheet" href="/temp-test-ioccc/ioccc.css">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
<title>2004/gavin</title>
<meta name="description" content="2004 IOCCC winner gavin">
<meta name="keywords" content="IOCCC, 2004, IOCCC 2004, IOCCC winner, gavin">
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<div class="header">
<img src="/temp-test-ioccc/png/ioccc.png" alt="IOCCC image by Matt Zucker" width=300 height=110>
<h1>The International Obfuscated C Code Contest</h1>
<h2>2004/gavin</h2>
</div>
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<div class="topnav">
<a class="Left" href="../gavare/index.html">&larr; gavare</a>
<a class="Left" href="../index.html">&uarr; 2004 &uarr;</a>
<a class="Left" href="../hibachi/index.html">hibachi &rarr;</a>
<a class="Right" href="#inventory">Inventory</a>
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<a href="#content">Jump to contents</a>
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<hr>
<div class="sidenav">
<a href="/temp-test-ioccc/index.html">IOCCC Home</a>
<a href="/temp-test-ioccc/years.html">Winning Entries</a>
<a href="/temp-test-ioccc/winners.html">People who have won</a>
</div>
<hr>
<div class="sidenav">
<a href="/temp-test-ioccc/news.html">IOCCC News</a>
<a href="/temp-test-ioccc/faq.html#submit">How to enter the IOCCC</a>
<a href="/temp-test-ioccc/faq.html">FAQ</a>
</div>
<hr>
<div class="sidenav">
<a href="/temp-test-ioccc/bugs.html">Bugs &amp; (mis)features</a>
<a href="/temp-test-ioccc/faq.html#fix_a_winner">Fixing IOCCC winners</a>
<a href="/temp-test-ioccc/faq.html#fix_web_site">Fixing the web site</a>
<a href="/temp-test-ioccc/faq.html#fix_author">Fixing winner info</a>
<a href="/temp-test-ioccc/thanks-for-help.html">Thanks for the help</a>
</div>
<hr>
<div class="sidenav">
<a href="/temp-test-ioccc/judges.html">The IOCCC Judges</a>
<a href="/temp-test-ioccc/contact.html">Contacting the IOCCC</a>
</div>
<hr>
<div class="sidenav">
<a href="#top">Jump to top</a>
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<p><a name="author"><strong>Author:</strong></a> <br><br>Name: <a
href="/temp-test-ioccc/winners.html#Gavin_Barraclough">Gavin
Barraclough</a><br> Location: <a
href="/temp-test-ioccc/location.html#null">unknown</a></p>
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<h2 id="to-build">To build:</h2>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="fu">make</span></span></code></pre></div>
<p>There is an alternate version for those who wish to use QEMU rather
than having to reboot and rely on having a floppy drive (if you even
remember what those are :-) ) etc. See <a
href="#alternate-code">alternate code</a> below.</p>
<h3 id="bugs-and-misfeatures">Bugs and (Mis)features:</h3>
<p>The current status of this entry is:</p>
<pre><code>STATUS: compiled executable crashes - please help us fix
STATUS: doesn&#39;t work with some platforms - please help us fix
STATUS: INABIAF - please **DO NOT** fix</code></pre>
<p>For more detailed information see <a href="/bugs.md#2004-gavin">2004
gavin in bugs.md</a>.</p>
<h2 id="to-use">To use:</h2>
<div class="sourceCode" id="cb3"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="ex">./gavin</span></span></code></pre></div>
<h2 id="try">Try:</h2>
<p>To enjoy the results (on a Linux/x86 machine) with a floppy drive
(remember those? We do!):</p>
<div class="sourceCode" id="cb4"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="fu">su</span></span></code></pre></div>
<p>Make a floppy with an ext2 filesystem (<code>mke2fs /dev/fd0</code>
replacing <code>fd0</code> with whatever the floppy device is!), mount
it under <code>/mnt/floppy</code> and then:</p>
<div class="sourceCode" id="cb5"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="fu">cp</span> kernel fs.tar lilo.conf boot.b /mnt/floppy</span></code></pre></div>
<p>NOTE: If the version of your lilo is not 21.4, use the appropriate
boot.b file.</p>
<p>NOTE: If your floppy drive is not <code>/dev/fd0</code>, edit
lilo.conf appropriately.</p>
<div class="sourceCode" id="cb6"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="ex">lilo</span> <span class="at">-C</span> /mnt/floppy/lilo.conf</span></code></pre></div>
<p>Boot from the floppy on an x86 machine with a PS/2 keyboard and
mouse. Move the window away from the corner.</p>
<div class="sourceCode" id="cb7"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="fu">vi</span> gavin.c</span></code></pre></div>
<p>Scroll up and down the file with up-arrow and down-arrow.</p>
<div class="sourceCode" id="cb8"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="fu">sh</span></span></code></pre></div>
<p>You can have several shell windows:</p>
<div class="sourceCode" id="cb9"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="fu">vi</span> README.md</span>
<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="ex">./prim</span></span></code></pre></div>
<p>Press and hold any key.</p>
<h2 id="alternate-code">Alternate code:</h2>
<p>This version’s main difference is that the macro <code>K</code> is
redefined to <code>1</code> so that you can use it with
<code>QEMU</code>.</p>
<h3 id="alternate-build">Alternate build:</h3>
<div class="sourceCode" id="cb10"><pre
class="sourceCode sh"><code class="sourceCode bash"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="fu">make</span> alt</span></code></pre></div>
<h3 id="alternate-use">Alternate use:</h3>
<p>The use is mostly the same as <code>gavin</code> except that one
initially executes <code>gavin.alt</code> (which <code>make alt</code>
will do) and one will have to use <code>QEMU</code> instead. The files
generated are the same names. See <a href="#to-use">to use</a> and <a
href="#try">try</a> above as well as the judges’ remarks below plus <a
href="gavin.md">gavin.md</a>.</p>
<h2 id="judges-remarks">Judges’ remarks:</h2>
<p>Over the years, we’ve seen a program that immediately dumps core if
executed on the “wrong” architectures (<a
href="1984/mullender/README.md">1984/mullender</a>) and a program that
dumps core after a while (<a
href="/2001/bellard/bellard.c">2001/bellard</a>). This entry will
happily compile and execute on most any architecture - the trick is that
the result, to be useful, must be produced (and can only be enjoyed) on
a particular architecture. We have not decided yet whether to disallow
this for future contests.</p>
<p>If you do not want to mess with a floppy and you use GRUB, see <a
href="gavin.md">gavin.md</a>.</p>
<p>You can put additional text files in <code>fs.tar</code> for browsing
with vi.</p>
<p>If you do not want to bother rebooting your computer at all, see <a
href="http://bellard.org" class="uri">http://bellard.org</a> for QEMU
(<a href="/winners.html#Fabrice_Bellard">Fabrice Bellard</a> is an IOCCC
2001 winner), but your experience will be limited; use the <a
href="#alternate-code">alternate code</a> instead. You’ll have to move
the mouse to trigger the initial screen update.</p>
<p>The judges were able to write a few more programs to run in this OS.
What are the limitations for such programs?</p>
<p>What can you do and what can you not do in such programs?</p>
<p>The program called <code>prim</code>, written by the judges, computes
and prints prime numbers.</p>
<h2 id="authors-remarks">Author’s remarks:</h2>
<p>This is a 32-bit multitasking operating system for x86 computers,
with GUI and filesystem, support for loading and executing user
applications in ELF binary format, with PS/2 mouse and keyboard drivers,
and VESA graphics. And a command shell. And an application - a simple
text-file viewer.</p>
<p>The OS has ended up as a traditional monolith with one entry point
for syscalls, with apps treated as cooperative-multitasking tasks that
can be sent different messages (e.g. ‘initialize’, ‘key hit’, ‘render to
buffer’) through their main entry point, and which will return control
to the OS after having performed the necessary work. Applications are
passed a pointer to their task structure, which is partially defined by
the OS, and partially for the application’s own use.</p>
<p>The program compiles into a tool to build a kernel image, so having
built the program, the <a href="Makefile">Makefile</a> will run it,
redirecting the output into a file called <code>kernel</code>. The
Makefile will then proceed to build a root filesystem image. This
involves rebuilding the program with different compiler flags, then
building a tarball containing the resulting programs (the filesystem
format supported by the OS is the tarball format).</p>
<p>For further usage information see <a
href="gavin.md">gavin.md</a>.</p>
<p>The filenames <code>vi</code> and <code>sh</code> are significant,
and should not be changed.</p>
<h3 id="known-features">Known ‘features’</h3>
<p>Known issues are really too plentiful to list.</p>
<p>If the mouse pointer goes off the left hand side of the screen it
will reappear on the right, and vice-versa. If it goes off the top or
bottom, it will go and corrupt some memory.</p>
<p>The file system is kinda optimistic about matching names, so, for
example if you type the command <code>shell</code> into a command-line
it will execute the program <code>sh</code> - close enough a match for
it.</p>
<p>The <a
href="https://en.wikipedia.org/wiki/Executable_and_Linkable_Format">ELF
binaries</a> are not loaded at the correct address, and their entry
point must be the start address of the <a
href="https://en.wikipedia.org/wiki/Code_segment">text segment</a>.</p>
<p>The keyboard driver can cope with the basic alpha-numeric keys, but
gets confused by fancy things like <code>shift</code> or
<code>backspace</code>.</p>
<p>In the text-file viewer, <code>vi</code>, the up/down and PgUp/PgDn
keys scroll up or down by one line. There is nothing to stop you from
scrolling above the top of the file, and pressing any other keys might
have an undefined effect.</p>
<p>The x86 is bootstrapped into 32bit mode in 6 instructions, with 4
more to set up data/stack segments and a stack-pointer to allow C code
to be run. On top of this there are also about a dozen instructions to
switch the video card into graphics mode. All in all, a relatively tiny
number of instructions next to the size of the C program. Also, the
string is mostly composed of data - a Linux-esque kernel header for the
bootloader, protected mode descriptor tables, keyboard maps, etc. (I
should also mention that it contains mini functions to perform an x86
<code>in</code> and <code>out</code> instruction - to allow the keyboard
&amp; mouse to be driven from C code).</p>
<p>Porting to another architecture should be relatively easy* - the
string simply needs be replaced with one containing data &amp; code
suitable for the new target platform. Accesses to data in the string are
made relative to the define <code>V</code>, so these may need updating
as appropriate (<code>0x90200</code> is the address at which a Linux
bootloader loads an x86 kernel image).</p>
<pre><code>\* ;-)</code></pre>
<h2 id="copyright-and-cc-by-sa-4.0-license">Copyright and CC BY-SA 4.0
License:</h2>
<p>This file is Copyright (c) 2023 by Landon Curt Noll. All Rights
Reserved. You are free to share and adapt this file under the terms of
this license:</p>
<pre><code>Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)</code></pre>
<p>For more information, see:
https://creativecommons.org/licenses/by-sa/4.0/</p>
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<h1 id="inventory-for-2004gavin"><a name="inventory"></a>Inventory for
2004/gavin</h1>
<h2 id="primary-files">Primary files</h2>
<ul>
<li><a href="index.html">index.html</a> - winner home page</li>
<li><a
href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2004/gavin/gavin.c">gavin.c</a>
- winning source</li>
<li><a
href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2004/gavin/Makefile">Makefile</a>
- winner Makefile</li>
<li><a
href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2004/gavin/gavin.alt.c">gavin.alt.c</a>
- alternative source</li>
<li><a
href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2004/gavin/gavin.orig.c">gavin.orig.c</a>
- original source</li>
<li><a href="gavin.html">gavin.html</a> - author usage guide</li>
<li><a
href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2004/gavin/lilo.conf">lilo.conf</a>
- boot loader configuration</li>
<li><a href="boot.b">boot.b</a> - boot sector</li>
<li><a href="img/fs.tar">img/fs.tar</a> - tar of root file system</li>
<li><a href="img/kernel">img/kernel</a> - Linux kernel x86 boot
executable zImage</li>
<li><a href="prim">prim</a> - prime number printing program</li>
<li><a href="2004_gavin.tar.bz2">2004_gavin.tar.bz2</a> - download
winning source</li>
</ul>
<h2 id="secondary-files">Secondary files</h2>
<ul>
<li><a
href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2004/gavin/.gitignore">.gitignore</a>
- list of files that should not be committed under git</li>
<li><a href=".path">.path</a> - directory path from top directory</li>
<li><a
href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2004/gavin/.winner.json">.winner.json</a>
- description of winner in JSON</li>
<li><a
href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2004/gavin/README.md">README.md</a>
- markdown source for index.html</li>
<li><a
href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2004/gavin/gavin.md">gavin.md</a>
- markdown source for gavin.html</li>
</ul>
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<hr>
<h2>Coda</h2>
<p><a href="https://validator.w3.org/nu/?doc=https%3A%2F%2Fioccc-src.github.io%2Ftemp-test-ioccc%2F2004%2Fgavin%2Findex.html">Nu HTML check this web page</a></p>
<p><a href="#top">Jump to top</a> <a href="#content">Jump to Content</a> <a href="#inventory">Jump to Inventory</a></p>
</div>
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