525 lines
16 KiB
PHP
525 lines
16 KiB
PHP
<?php
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/* PEL: PHP Exif Library. A library with support for reading and
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* writing all Exif headers in JPEG and TIFF images using PHP.
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*
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* Copyright (C) 2004, 2005 Martin Geisler.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program in the file COPYING; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301 USA
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*/
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/* $Id: PelDataWindow.php 387 2005-10-05 11:02:52Z mgeisler $ */
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/**
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* A container for bytes with a limited window of accessible bytes.
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*
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* @author Martin Geisler <mgeisler@users.sourceforge.net>
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* @version $Revision: 387 $
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* @date $Date: 2005-10-05 13:02:52 +0200 (Wed, 05 Oct 2005) $
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* @license http://www.gnu.org/licenses/gpl.html GNU General Public License (GPL)
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* @package PEL
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*/
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/**#@+ Required class definitions. */
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require_once('PelException.php');
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require_once('PelConvert.php');
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/**#@-*/
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/**
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* An exception thrown when an invalid offset is encountered.
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*
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* @package PEL
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* @subpackage Exception
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*/
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class PelDataWindowOffsetException extends PelException {}
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/**
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* An exception thrown when an invalid window is encountered.
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*
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* @package PEL
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* @subpackage Exception
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*/
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class PelDataWindowWindowException extends PelException {}
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/**
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* The window.
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*
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* @package PEL
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*/
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class PelDataWindow {
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/**
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* The data held by this window.
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*
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* The string can contain any kind of data, including binary data.
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*
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* @var string
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*/
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private $data = '';
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/**
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* The byte order currently in use.
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*
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* This will be the byte order used when data is read using the for
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* example the {@link getShort} function. It must be one of {@link
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* PelConvert::LITTLE_ENDIAN} and {@link PelConvert::BIG_ENDIAN}.
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*
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* @var PelByteOrder
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* @see setByteOrder, getByteOrder
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*/
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private $order;
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/**
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* The start of the current window.
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*
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* All offsets used for access into the data will count from this
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* offset, effectively limiting access to a window starting at this
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* byte.
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*
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* @var int
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* @see setWindowStart
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*/
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private $start = 0;
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/**
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* The size of the current window.
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*
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* All offsets used for access into the data will be limited by this
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* variable. A valid offset must be strictly less than this
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* variable.
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*
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* @var int
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* @see setWindowSize
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*/
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private $size = 0;
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/**
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* Construct a new data window with the data supplied.
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*
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* @param string the data that this window will contain. The data
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* will be copied into the new data window.
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*
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* @param boolean the initial byte order of the window. This must
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* be either {@link PelConvert::LITTLE_ENDIAN} or {@link
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* PelConvert::BIG_ENDIAN}. This will be used when integers are
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* read from the data, and it can be changed later with {@link
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* setByteOrder()}.
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*/
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function __construct($d = '', $e = PelConvert::LITTLE_ENDIAN) {
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$this->data = $d;
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$this->order = $e;
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$this->size = strlen($d);
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}
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/**
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* Get the size of the data window.
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*
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* @return int the number of bytes covered by the window. The
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* allowed offsets go from 0 up to this number minus one.
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*
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* @see getBytes()
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*/
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function getSize() {
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return $this->size;
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}
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/**
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* Change the byte order of the data.
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*
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* @param PelByteOrder the new byte order. This must be either
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* {@link PelConvert::LITTLE_ENDIAN} or {@link
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* PelConvert::BIG_ENDIAN}.
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*/
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function setByteOrder($o) {
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$this->order = $o;
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}
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/**
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* Get the currently used byte order.
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*
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* @return PelByteOrder this will be either {@link
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* PelConvert::LITTLE_ENDIAN} or {@link PelConvert::BIG_ENDIAN}.
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*/
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function getByteOrder() {
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return $this->order;
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}
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/* Move the start of the window forward.
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*
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* @param int the new start of the window. All new offsets will be
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* calculated from this new start offset, and the size of the window
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* will shrink to keep the end of the window in place.
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*/
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function setWindowStart($start) {
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if ($start < 0 || $start > $this->size)
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throw new PelDataWindowWindowException('Window [%d, %d] does ' .
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'not fit in window [0, %d]',
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$start, $this->size, $this->size);
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$this->start += $start;
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$this->size -= $start;
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}
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/**
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* Adjust the size of the window.
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*
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* The size can only be made smaller.
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*
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* @param int the desired size of the window. If the argument is
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* negative, the window will be shrunk by the argument.
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*/
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function setWindowSize($size) {
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if ($size < 0)
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$size += $this->size;
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if ($size < 0 || $size > $this->size)
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throw new PelDataWindowWindowException('Window [0, %d] ' .
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'does not fit in window [0, %d]',
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$size, $this->size);
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$this->size = $size;
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}
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/**
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* Make a new data window with the same data as the this window.
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*
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* @param mixed if an integer is supplied, then it will be the start
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* of the window in the clone. If left unspecified, then the clone
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* will inherit the start from this object.
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*
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* @param mixed if an integer is supplied, then it will be the size
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* of the window in the clone. If left unspecified, then the clone
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* will inherit the size from this object.
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*
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* @return PelDataWindow a new window that operates on the same data
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* as this window, but (optionally) with a smaller window size.
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*/
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function getClone($start = false, $size = false) {
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$c = clone $this;
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if (is_int($start))
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$c->setWindowStart($start);
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if (is_int($size))
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$c->setWindowSize($size);
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return $c;
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}
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/**
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* Validate an offset against the current window.
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*
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* @param int the offset to be validated. If the offset is negative
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* or if it is greater than or equal to the current window size,
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* then a {@link PelDataWindowOffsetException} is thrown.
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*
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* @return void if the offset is valid nothing is returned, if it is
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* invalid a new {@link PelDataWindowOffsetException} is thrown.
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*/
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private function validateOffset($o) {
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if ($o < 0 || $o >= $this->size)
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throw new PelDataWindowOffsetException('Offset %d not within [%d, %d]',
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$o, 0, $this->size-1);
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}
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/**
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* Return some or all bytes visible in the window.
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*
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* This method works just like the standard {@link substr()}
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* function in PHP with the exception that it works within the
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* window of accessible bytes and does strict range checking.
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*
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* @param int the offset to the first byte returned. If a negative
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* number is given, then the counting will be from the end of the
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* window. Invalid offsets will result in a {@link
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* PelDataWindowOffsetException} being thrown.
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*
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* @param int the size of the sub-window. If a negative number is
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* given, then that many bytes will be omitted from the result.
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*
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* @return string a subset of the bytes in the window. This will
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* always return no more than {@link getSize()} bytes.
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*/
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function getBytes($start = false, $size = false) {
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if (is_int($start)) {
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if ($start < 0)
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$start += $this->size;
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$this->validateOffset($start);
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} else {
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$start = 0;
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}
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if (is_int($size)) {
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if ($size <= 0)
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$size += $this->size - $start;
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$this->validateOffset($start+$size);
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} else {
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$size = $this->size - $start;
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}
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return substr($this->data, $this->start + $start, $size);
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}
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/**
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* Return an unsigned byte from the data.
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*
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* @param int the offset into the data. An offset of zero will
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* return the first byte in the current allowed window. The last
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* valid offset is equal to {@link getSize()}-1. Invalid offsets
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* will result in a {@link PelDataWindowOffsetException} being
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* thrown.
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*
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* @return int the unsigned byte found at offset.
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*/
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function getByte($o = 0) {
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/* Validate the offset --- this throws an exception if offset is
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* out of range. */
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$this->validateOffset($o);
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/* Translate the offset into an offset into the data. */
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$o += $this->start;
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/* Return an unsigned byte. */
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return PelConvert::bytesToByte($this->data, $o);
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}
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/**
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* Return a signed byte from the data.
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*
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* @param int the offset into the data. An offset of zero will
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* return the first byte in the current allowed window. The last
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* valid offset is equal to {@link getSize()}-1. Invalid offsets
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* will result in a {@link PelDataWindowOffsetException} being
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* thrown.
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*
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* @return int the signed byte found at offset.
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*/
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function getSByte($o = 0) {
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/* Validate the offset --- this throws an exception if offset is
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* out of range. */
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$this->validateOffset($o);
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/* Translate the offset into an offset into the data. */
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$o += $this->start;
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/* Return a signed byte. */
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return PelConvert::bytesToSByte($this->data, $o);
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}
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/**
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* Return an unsigned short read from the data.
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*
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* @param int the offset into the data. An offset of zero will
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* return the first short available in the current allowed window.
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* The last valid offset is equal to {@link getSize()}-2. Invalid
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* offsets will result in a {@link PelDataWindowOffsetException}
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* being thrown.
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*
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* @return int the unsigned short found at offset.
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*/
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function getShort($o = 0) {
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/* Validate the offset+1 to see if we can safely get two bytes ---
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* this throws an exception if offset is out of range. */
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$this->validateOffset($o);
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$this->validateOffset($o+1);
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/* Translate the offset into an offset into the data. */
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$o += $this->start;
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/* Return an unsigned short. */
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return PelConvert::bytesToShort($this->data, $o, $this->order);
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}
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/**
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* Return a signed short read from the data.
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*
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* @param int the offset into the data. An offset of zero will
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* return the first short available in the current allowed window.
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* The last valid offset is equal to {@link getSize()}-2. Invalid
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* offsets will result in a {@link PelDataWindowOffsetException}
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* being thrown.
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*
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* @return int the signed short found at offset.
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*/
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function getSShort($o = 0) {
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/* Validate the offset+1 to see if we can safely get two bytes ---
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* this throws an exception if offset is out of range. */
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$this->validateOffset($o);
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$this->validateOffset($o+1);
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/* Translate the offset into an offset into the data. */
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$o += $this->start;
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/* Return a signed short. */
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return PelConvert::bytesToSShort($this->data, $o, $this->order);
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}
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/**
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* Return an unsigned long read from the data.
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*
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* @param int the offset into the data. An offset of zero will
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* return the first long available in the current allowed window.
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* The last valid offset is equal to {@link getSize()}-4. Invalid
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* offsets will result in a {@link PelDataWindowOffsetException}
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* being thrown.
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*
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* @return int the unsigned long found at offset.
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*/
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function getLong($o = 0) {
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/* Validate the offset+3 to see if we can safely get four bytes
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* --- this throws an exception if offset is out of range. */
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$this->validateOffset($o);
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$this->validateOffset($o+3);
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/* Translate the offset into an offset into the data. */
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$o += $this->start;
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/* Return an unsigned long. */
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return PelConvert::bytesToLong($this->data, $o, $this->order);
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}
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/**
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* Return a signed long read from the data.
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*
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* @param int the offset into the data. An offset of zero will
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* return the first long available in the current allowed window.
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* The last valid offset is equal to {@link getSize()}-4. Invalid
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* offsets will result in a {@link PelDataWindowOffsetException}
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* being thrown.
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*
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* @return int the signed long found at offset.
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*/
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function getSLong($o = 0) {
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/* Validate the offset+3 to see if we can safely get four bytes
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* --- this throws an exception if offset is out of range. */
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$this->validateOffset($o);
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$this->validateOffset($o+3);
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/* Translate the offset into an offset into the data. */
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$o += $this->start;
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/* Return a signed long. */
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return PelConvert::bytesToSLong($this->data, $o, $this->order);
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}
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/**
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* Return an unsigned rational read from the data.
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*
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* @param int the offset into the data. An offset of zero will
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* return the first rational available in the current allowed
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* window. The last valid offset is equal to {@link getSize()}-8.
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* Invalid offsets will result in a {@link
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* PelDataWindowOffsetException} being thrown.
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*
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* @return array the unsigned rational found at offset. A rational
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* number is represented as an array of two numbers: the enumerator
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* and denominator. Both of these numbers will be unsigned longs.
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*/
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function getRational($o = 0) {
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return array($this->getLong($o), $this->getLong($o+4));
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}
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/**
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* Return a signed rational read from the data.
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*
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* @param int the offset into the data. An offset of zero will
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* return the first rational available in the current allowed
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* window. The last valid offset is equal to {@link getSize()}-8.
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* Invalid offsets will result in a {@link
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* PelDataWindowOffsetException} being thrown.
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*
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* @return array the signed rational found at offset. A rational
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* number is represented as an array of two numbers: the enumerator
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* and denominator. Both of these numbers will be signed longs.
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*/
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function getSRational($o = 0) {
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return array($this->getSLong($o), $this->getSLong($o+4));
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}
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/**
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* String comparison on substrings.
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*
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* @param int the offset into the data. An offset of zero will make
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* the comparison start with the very first byte available in the
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* window. The last valid offset is equal to {@link getSize()}
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* minus the length of the string. If the string is too long, then
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* a {@link PelDataWindowOffsetException} will be thrown.
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*
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* @param string the string to compare with.
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*
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* @return boolean true if the string given matches the data in the
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* window, at the specified offset, false otherwise. The comparison
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* will stop as soon as a mismatch if found.
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*/
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function strcmp($o, $str) {
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/* Validate the offset of the final character we might have to
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* check. */
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$s = strlen($str);
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$this->validateOffset($o);
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$this->validateOffset($o + $s - 1);
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/* Translate the offset into an offset into the data. */
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$o += $this->start;
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/* Check each character, return as soon as the answer is known. */
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for ($i = 0; $i < $s; $i++) {
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if ($this->data{$o + $i} != $str{$i})
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return false;
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}
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/* All characters matches each other, return true. */
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return true;
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}
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/**
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* Return a string representation of the data window.
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*
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* @return string a description of the window with information about
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* the number of bytes accessible, the total number of bytes, and
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* the window start and stop.
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*/
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function __toString() {
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return Pel::fmt('DataWindow: %d bytes in [%d, %d] of %d bytes',
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$this->size,
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$this->start, $this->start + $this->size,
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strlen($this->data));
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}
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}
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?>
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