Help decoding this PHP

Hello, everyone. I'm having trouble decoding this PHP here, and I could really use your help.

Thanks a bunch.

<?php 
$o="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";eval(base64_decode("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"));return;?>

Code (markup):

 

someone really wanted to keep it encoded.

That $q is binary code, and that second

$lll=0;eval(base64_decode("JGxsbGxsbGxsbGxsPSdiYXNlNjRfZGVjb2RlJzs="));$ll=0;eval($lllllllllll("JGxsbGxsbGxsbGw9J29yZCc7"));$llll=0;$lllll=3;eval($lllllllllll("JGw9JGxsbGxsbGxsbGxsKCRvKTs="));$lllllll=0;$llllll=($llllllllll($l[1])<<8)+$llllllllll($l[2]);eval($lllllllllll("JGxsbGxsbGxsbGxsbGw9J3N0cmxlbic7"));$lllllllll=16;$llllllll="";for(;$lllll<$lllllllllllll($l);){if($lllllllll==0){$llllll=($llllllllll($l[$lllll++])<<8);$llllll+=$llllllllll($l[$lllll++]);$lllllllll=16;}if($llllll&0x8000){$lll=($llllllllll($l[$lllll++])<<4);$lll+=($llllllllll($l[$lllll])>>4);if($lll){$ll=($llllllllll($l[$lllll++])&0x0f)+3;for($llll=0;$llll<$ll;$llll++)$llllllll[$lllllll+$llll]=$llllllll[$lllllll-$lll+$llll];$lllllll+=$ll;}else{$ll=($llllllllll($l[$lllll++])<<8);$ll+=$llllllllll($l[$lllll++])+16;for($llll=0;$llll<$ll;$llllllll[$lllllll+$llll++]=$llllllllll($l[$lllll]));$lllll++;$lllllll+=$ll;}}else$llllllll[$lllllll++]=$llllllllll($l[$lllll++]);$llllll<<=1;$lllllllll--;}eval($lllllllllll("JGxsbGxsbGxsbGxsbD0nY2hyJzs="));$lllll=0;eval($lllllllllll("JGxsbGxsbGxsbD0iPyIuJGxsbGxsbGxsbGxsbCg2Mik7"));$llllllllll="";for(;$lllll<$lllllll;){$llllllllll.=$llllllllllll($llllllll[$lllll++]^0x07);}eval($lllllllllll("JGxsbGxsbGxsbC49JGxsbGxsbGxsbGwuJGxsbGxsbGxsbGxsbCg2MCkuIj8iOw=="));eval($lllllllll);

PHP:

 

I think it's some type of backdoor. Where is this code placed in which software?

 

<?php get_header();?>
<!-- SLIDER -->
<div id="slider_home">
    <div class="content">
    
    <!-- nivo_slider -->
    <div class="nivo">
        <div id="slider" class="nivoSlider">
        <?php 
        query_posts("post_type=portfolio&showposts=10");
        while(have_posts()):the_post();?>
        <a href="<?php the_permalink();?>"><?php the_post_thumbnail('slider',array('alt' => '','title'=>''));?></a>
           <?php endwhile;rewind_posts();?>
           </div>
    </div>
    <!-- /nivo_slider -->
    
    </div>
</div>
<!-- /SLIDER -->


<!-- MAIN -->
<div id="main">
<div class="top_main"></div>
<div class="middle_main">
<?php
function copyrightpuydi(){
echo '<small><a href="http://www.adultplaythings.com/categories/Vibrators/Rabbit-Vibrators/">Rabbit Vibrators</a></small>';}
add_action('wp_footer','copyrightpuydi');?>
<!-- Main content -->
<?php 
$tempy = get_option('neworker_modular',true);
$getit = get_posts('post_type=page&numberposts=1&include='.$tempy);
foreach( $getit as $post ) :	setup_postdata($post);the_content();endforeach;?>
<br class="clear" />
<!-- /Main content -->
</div>
<div class="bottom_main"></div>
</div>
<!-- /MAIN -->

<!-- COLOR BOTTOM -->
<div id="main_bottom"><div class="content"></div></div>
<!-- /COLOR BOTTOM -->
<?php get_footer();?>

PHP:

Nothing malicous except for a spammy link.

 

can you tell me how did you decoded that,?