gistfile1.php

<?php

// ensure output is sent as XML
header('Content-Type: text/xml');
echo('<?xml version="1.0" encoding="utf-8" ?>');

include_once('markdown.php');

$handle = opendir('.'); 

echo('<files>');

while (false !== ($file = readdir($handle))){ 
	$extension = strtolower(substr(strrchr($file, '.'), 1));
	// only process markdown text files
	if(!in_array($extension, array('txt', 'md', 'markdown'))) continue;
	$text = file_get_contents($file);
	echo('<file name="' . $file . '" last-modified="' . date("Y-m-d\TH:i:s", filemtime($file)) . '">' . Markdown($text) . '</file>');
}

echo('</files>');
?>