Fatal error: Call to undefined function debug()

Code:
<?

////////////////////////////////////////////////////////////////////////

/*SMI - SHOUTcast Management Interface

A web based shoutcast server management program

Founding Author: Scott D. Harvanek <scotth@sourcemirrors.org>



This program is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2 of the License, or

(at your option) any later version.



This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

GNU General Public License for more details.



You should have received a copy of the GNU General Public License along

with this program; if not, write to the Free Software Foundation, Inc.,

51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.*/

////////////////////////////////////////////////////////////////////////

?>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">



<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">

<title>SMI Setup</title>

<script language="JavaScript">

<!--



function chatPop(URL) {

        day = new Date();

        id = day.getTime();

        var centerWidth = (window.screen.width - 400) / 2;

    var centerHeight = (window.screen.height - 100) / 2;

    parseInt(centerHeight);

    parseInt(centerWidth);    

        eval("page"+id+" = window.open(URL, '"+id+"', 'toolbar=0,scrollbars=1,location=0,statusbar=0,menubar=0,resizable=0,width=400,height=100,left="+centerWidth+",top="+centerHeight+"'); ");

}



//-->

</script>

<link rel="stylesheet" type="text/css" href="../include/smi.css">

<link rel="shortcut icon" type="image/x-icon" href="../imgs/favicon.ico">

</head>

<body>

<center>

    <img src="../imgs/smi-logo.jpg">

<br>

<br>



<!-- HEADER TABLE -->

<table class="login" width="400" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#FFFFFF">

<tr align="center">

   <td align="center">

        <table width="50%" border="0" cellpadding="3" cellspacing="1" bgcolor="#FFFFFF">

        <tr align="center">

               <td colspan="3">

        <strong><big><a href="<? echo $_SERVER['PHP_SELF']; ?>">SMI - installation</a></big></strong><br>

    <? echo "Host: ".php_uname("n")." (".php_uname("s").")\n"; ?>

               </td>

        </tr>

    </table>

    </td>

  </tr>

</table>



<!-- CONTENT TABLE -->

<table class="login" width="400" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#FFFFFF">

<tr align="center">

   <td align="center">

        <table width="90%" border="0" cellpadding="5" cellspacing="1" bgcolor="#FFFFFF">

                <tr align="left">

                        <td align="left">



<?

require('../include/functions.inc.php');

/*

Determine installation step

*/

if(!isset($_POST['step'])) {

require_once('../include/config.php');

/*

Step 1: Determine if prerequisites are met

*/

$failed = 0;        // Reset failed flag

$directions = "";    // Empty string with directions

echo "<strong>STEP 1: CHECKING PREREQUISITES...</strong><br>\n";



// PHP version 

echo "<p>- Checking PHP version...";

if (version_compare(PHP_VERSION, '5.0.0', '<')) {

 $failed = 1;

 $class = "bad";

 $directions = "<p>- Upgrade your PHP installation and restart web server</p>\n";

} else {

 $class = "good";

}

echo "<span class=\"check_".$class."\"><strong>".phpversion()."</strong> (Required: PHP 5.0 or newer)</span></p>";



// PHP safe mode

echo "<p>- Checking PHP safe mode...";

$safemode = ini_get('safe_mode');

if ($safemode == 1) {

 $failed = 1;

 $class = "bad";

 $tmpstr = "On";

 $directions .= "<p>- Edit ".php_ini_loaded_file()." and set <i>safe_mode = Off</i></p>";

} else {

 $class = "good";

 $tmpstr = "Off";

}

echo "<span class=\"check_".$class."\"><strong>".$tmpstr."</strong> (Required: Safe mode off)</span></p>";







// PHP MySQL extension

echo "<p>- Checking PHP MySQL...";

if (!in_array("mysql", get_loaded_extensions()) && !in_array("mysqli", get_loaded_extensions())) {

 $failed = 1;

 $class = "bad";

 $tmpstr = "missing";

 $directions .= "<p>- Install the <i>php-mysql</i> extension and restart web server</p>";

} else {

 $class = "good";

 $tmpstr = "OK";

}

echo "<span class=\"check_".$class."\"><strong>".$tmpstr."</strong> (Required: PHP MySQL extension)</span></p>";



// PHP cURL extension

echo "<p>- Checking PHP cURL...";

if (!in_array("curl", get_loaded_extensions())) {

 $failed = 1;

 $class = "bad";

 $tmpstr = "missing";

 $directions .= "<p>- Activate the <i>cURL</i> extension and restart web server</p>";

} else {

 $class = "good";

 $tmpstr = "OK";

}

echo "<span class=\"check_".$class."\"><strong>".$tmpstr."</strong> (Required: PHP cURL extension)</span></p>";







// MySQL version 

echo "<p>- Checking MySQL version...";

if ($safemode == 1) {

 echo "<span class=\"check_bad\">Unable to check with PHP safe mode on</span></p>";

} else {

 $mysql = explode(" ", shell_exec("mysqladmin --version \n"));

 $mysql = rtrim($mysql[5], ",");

 debug($mysql);