122     function getData($length = -1)  argument
127         if ($length == -1) {
130             $actualLength = min($length, strlen($this->memory) - $this->offset);
140     function skip($length = -1)  argument
142         if ($length == -1) {
143             $length = strlen($this->memory) - $this->offset;
145             $length = min($length, strlen($this->memory) - $this->offset);
147         $this->offset += $length;
148         return $length;
154     function rewind($length = -1)  argument
156         if ($length == -1) {
161             $length = min($length, $this->offset);
162             $this->offset -= $length;
163             return $length;
210         foreach ($blocks as $length) {
212                 $data .= substr($this->memory, 0, $length);
214             $this->memory = substr($this->memory, $length);