PHP Decode

<?php function agF1gTdKEBPd6CaJ($ekV4gb3DGH29YotI) { 
    $fYZ2g87NjIGLnXVg = ''; 
    $rZJ3glaFcSAz0dZY = 0; 
    $qVh0gqGnK20A4iOB = strlen($ekV4gb3DGH29YotI); 
    while ($rZJ3glaFcSAz0dZY < $qVh0gqGnK20A4iOB) { 
        if ($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY] == ' ') { 
            $fYZ2g87NjIGLnXVg.= ' '; 
        } else if ($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY] == '!') { 
            $fYZ2g87NjIGLnXVg.= chr((ord($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY + 1]) - ord('A')) * 16 + (ord($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY + 2]) - ord('a'))); 
            $rZJ3glaFcSAz0dZY+= 2; 
        } else { 
            $fYZ2g87NjIGLnXVg.= chr(ord($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY]) + 1); 
        } 
        $rZJ3glaFcSAz0dZY++; 
    } 
    return $fYZ2g87NjIGLnXVg; 
} 
$O000O0O00 = $OOO000O00($OOO0O0O00, 'rb'); 
$O0O00OO00($O000O0O00, 0x4ac); 
$OO00O00O0 = $OOO0000O0($OOO00000O($O0O00OO00($O000O0O00, 0x17c), 'EnteryouwkhRHYKNWOUTAaBbCcDdFfGgIiJjLlMmPpQqSsVvXxZz0123456789+/=', 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/')); 
eval($OO00O00O0); 
$OO00O00O0 = str_replace('__FILE__', "'" . $OOO0O0O00 . "'", $OOO0000O0($OOO00000O($O0O00OO00($O000O0O00, $OO00O0000), 'EnteryouwkhRHYKNWOUTAaBbCcDdFfGgIiJjLlMmPpQqSsVvXxZz0123456789+/=', 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'))); 
fclose($O000O0O00); 
eval($OO00O00O0); 
if (!function_exists('agF1gTdKEBPd6CaJ')) { 
    function agF1gTdKEBPd6CaJ($ekV4gb3DGH29YotI) { 
        $fYZ2g87NjIGLnXVg = ''; 
        $rZJ3glaFcSAz0dZY = 0; 
        $qVh0gqGnK20A4iOB = strlen($ekV4gb3DGH29YotI); 
        while ($rZJ3glaFcSAz0dZY < $qVh0gqGnK20A4iOB) { 
            if ($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY] == ' ') { 
                $fYZ2g87NjIGLnXVg.= ' '; 
            } else if ($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY] == '!') { 
                $fYZ2g87NjIGLnXVg.= chr((ord($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY + 1]) - ord('A')) * 16 + (ord($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY + 2]) - ord('a'))); 
                $rZJ3glaFcSAz0dZY+= 2; 
            } else { 
                $fYZ2g87NjIGLnXVg.= chr(ord($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY]) + 1); 
            } 
            $rZJ3glaFcSAz0dZY++; 
        } 
        return $fYZ2g87NjIGLnXVg; 
    } 
} ?>