log reader php

<?php
$maxlines=5000;
$fp=fopen('log.txt','r');
if(!$fp) exit("couldn't open log");
if(isset($_GET['start'])) $start=$_GET['start']; else {
        $cnt=0;
        while(!feof($fp)){ $line=fgets($fp); $cnt++; }
        rewind($fp);
        if($cnt>$maxlines) $start=$cnt-$maxlines-1; else $start=0;
}
$i=0;
while(!feof($fp)){
        $line=fgets($fp);
        if(empty(trim($line))) continue;
        if(strpos($line,'****')!==false) continue;
        if($i<$start){ $i++; continue; }
        echo $line;
        $i++;
}
echo "/*asdf*/$i"; // output separator and current highest line number