397 lines
12 KiB
PHP
397 lines
12 KiB
PHP
|
<?php
|
||
|
|
||
|
/* PEL: PHP Exif Library. A library with support for reading and
|
||
|
* writing all Exif headers in JPEG and TIFF images using PHP.
|
||
|
*
|
||
|
* Copyright (C) 2004, 2005 Martin Geisler.
|
||
|
*
|
||
|
* This program is free software; you can redistribute it and/or modify
|
||
|
* it under the terms of the GNU General Public License as published by
|
||
|
* the Free Software Foundation; either version 2 of the License, or
|
||
|
* (at your option) any later version.
|
||
|
*
|
||
|
* This program is distributed in the hope that it will be useful,
|
||
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
|
* GNU General Public License for more details.
|
||
|
*
|
||
|
* You should have received a copy of the GNU General Public License
|
||
|
* along with this program in the file COPYING; if not, write to the
|
||
|
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
|
||
|
* Boston, MA 02110-1301 USA
|
||
|
*/
|
||
|
|
||
|
/* $Id: PelConvert.php 387 2005-10-05 11:02:52Z mgeisler $ */
|
||
|
|
||
|
|
||
|
/**
|
||
|
* Routines for converting back and forth between bytes and integers.
|
||
|
*
|
||
|
* @author Martin Geisler <mgeisler@users.sourceforge.net>
|
||
|
* @version $Revision: 387 $
|
||
|
* @date $Date: 2005-10-05 13:02:52 +0200 (Wed, 05 Oct 2005) $
|
||
|
* @license http://www.gnu.org/licenses/gpl.html GNU General Public
|
||
|
* License (GPL)
|
||
|
* @package PEL
|
||
|
*/
|
||
|
|
||
|
/**
|
||
|
* Conversion functions to and from bytes and integers.
|
||
|
*
|
||
|
* The functions found in this class are used to convert bytes into
|
||
|
* integers of several sizes ({@link bytesToShort}, {@link
|
||
|
* bytesToLong}, and {@link bytesToRational}) and convert integers of
|
||
|
* several sizes into bytes ({@link shortToBytes} and {@link
|
||
|
* longToBytes}).
|
||
|
*
|
||
|
* All the methods are static and they all rely on an argument that
|
||
|
* specifies the byte order to be used, this must be one of the class
|
||
|
* constants {@link LITTLE_ENDIAN} or {@link BIG_ENDIAN}. These
|
||
|
* constants will be referred to as the pseudo type PelByteOrder
|
||
|
* throughout the documentation.
|
||
|
*
|
||
|
* @author Martin Geisler <mgeisler@users.sourceforge.net>
|
||
|
* @package PEL
|
||
|
*/
|
||
|
class PelConvert {
|
||
|
|
||
|
/**
|
||
|
* Little-endian (Intel) byte order.
|
||
|
*
|
||
|
* Data stored in little-endian byte order store the least
|
||
|
* significant byte first, so the number 0x12345678 becomes 0x78
|
||
|
* 0x56 0x34 0x12 when stored with little-endian byte order.
|
||
|
*/
|
||
|
const LITTLE_ENDIAN = true;
|
||
|
|
||
|
/**
|
||
|
* Big-endian (Motorola) byte order.
|
||
|
*
|
||
|
* Data stored in big-endian byte order store the most significant
|
||
|
* byte first, so the number 0x12345678 becomes 0x12 0x34 0x56 0x78
|
||
|
* when stored with big-endian byte order.
|
||
|
*/
|
||
|
const BIG_ENDIAN = false;
|
||
|
|
||
|
|
||
|
/**
|
||
|
* Convert an unsigned short into two bytes.
|
||
|
*
|
||
|
* @param int the unsigned short that will be converted. The lower
|
||
|
* two bytes will be extracted regardless of the actual size passed.
|
||
|
*
|
||
|
* @param PelByteOrder one of {@link LITTLE_ENDIAN} and {@link
|
||
|
* BIG_ENDIAN}.
|
||
|
*
|
||
|
* @return string the bytes representing the unsigned short.
|
||
|
*/
|
||
|
static function shortToBytes($value, $endian) {
|
||
|
if ($endian == self::LITTLE_ENDIAN)
|
||
|
return chr($value) . chr($value >> 8);
|
||
|
else
|
||
|
return chr($value >> 8) . chr($value);
|
||
|
}
|
||
|
|
||
|
|
||
|
/**
|
||
|
* Convert a signed short into two bytes.
|
||
|
*
|
||
|
* @param int the signed short that will be converted. The lower
|
||
|
* two bytes will be extracted regardless of the actual size passed.
|
||
|
*
|
||
|
* @param PelByteOrder one of {@link LITTLE_ENDIAN} and {@link
|
||
|
* BIG_ENDIAN}.
|
||
|
*
|
||
|
* @return string the bytes representing the signed short.
|
||
|
*/
|
||
|
static function sShortToBytes($value, $endian) {
|
||
|
/* We can just use shortToBytes, since signed shorts fits well
|
||
|
* within the 32 bit signed integers used in PHP. */
|
||
|
return self::shortToBytes($value, $endian);
|
||
|
}
|
||
|
|
||
|
|
||
|
/**
|
||
|
* Convert an unsigned long into four bytes.
|
||
|
*
|
||
|
* Because PHP limits the size of integers to 32 bit signed, one
|
||
|
* cannot really have an unsigned integer in PHP. But integers
|
||
|
* larger than 2^31-1 will be promoted to 64 bit signed floating
|
||
|
* point numbers, and so such large numbers can be handled too.
|
||
|
*
|
||
|
* @param int the unsigned long that will be converted. The
|
||
|
* argument will be treated as an unsigned 32 bit integer and the
|
||
|
* lower four bytes will be extracted. Treating the argument as an
|
||
|
* unsigned integer means that the absolute value will be used. Use
|
||
|
* {@link sLongToBytes} to convert signed integers.
|
||
|
*
|
||
|
* @param PelByteOrder one of {@link LITTLE_ENDIAN} and {@link
|
||
|
* BIG_ENDIAN}.
|
||
|
*
|
||
|
* @return string the bytes representing the unsigned long.
|
||
|
*/
|
||
|
static function longToBytes($value, $endian) {
|
||
|
/* We cannot convert the number to bytes in the normal way (using
|
||
|
* shifts and modulo calculations) because the PHP operator >> and
|
||
|
* function chr() clip their arguments to 2^31-1, which is the
|
||
|
* largest signed integer known to PHP. But luckily base_convert
|
||
|
* handles such big numbers. */
|
||
|
$hex = str_pad(base_convert($value, 10, 16), 8, '0', STR_PAD_LEFT);
|
||
|
if ($endian == self::LITTLE_ENDIAN)
|
||
|
return (chr(hexdec($hex{6} . $hex{7})) .
|
||
|
chr(hexdec($hex{4} . $hex{5})) .
|
||
|
chr(hexdec($hex{2} . $hex{3})) .
|
||
|
chr(hexdec($hex{0} . $hex{1})));
|
||
|
else
|
||
|
return (chr(hexdec($hex{0} . $hex{1})) .
|
||
|
chr(hexdec($hex{2} . $hex{3})) .
|
||
|
chr(hexdec($hex{4} . $hex{5})) .
|
||
|
chr(hexdec($hex{6} . $hex{7})));
|
||
|
}
|
||
|
|
||
|
|
||
|
/**
|
||
|
* Convert a signed long into four bytes.
|
||
|
*
|
||
|
* @param int the signed long that will be converted. The argument
|
||
|
* will be treated as a signed 32 bit integer, from which the lower
|
||
|
* four bytes will be extracted.
|
||
|
*
|
||
|
* @param PelByteOrder one of {@link LITTLE_ENDIAN} and {@link
|
||
|
* BIG_ENDIAN}.
|
||
|
*
|
||
|
* @return string the bytes representing the signed long.
|
||
|
*/
|
||
|
static function sLongToBytes($value, $endian) {
|
||
|
/* We can convert the number into bytes in the normal way using
|
||
|
* shifts and modulo calculations here (in contrast with
|
||
|
* longToBytes) because PHP automatically handles 32 bit signed
|
||
|
* integers for us. */
|
||
|
if ($endian == self::LITTLE_ENDIAN)
|
||
|
return (chr($value) .
|
||
|
chr($value >> 8) .
|
||
|
chr($value >> 16) .
|
||
|
chr($value >> 24));
|
||
|
else
|
||
|
return (chr($value >> 24) .
|
||
|
chr($value >> 16) .
|
||
|
chr($value >> 8) .
|
||
|
chr($value));
|
||
|
}
|
||
|
|
||
|
|
||
|
/**
|
||
|
* Extract an unsigned byte from a string of bytes.
|
||
|
*
|
||
|
* @param string the bytes.
|
||
|
*
|
||
|
* @param int the offset. The byte found at the offset will be
|
||
|
* returned as an integer. The must be at least one byte available
|
||
|
* at offset.
|
||
|
*
|
||
|
* @return int the unsigned byte found at offset, e.g., an integer
|
||
|
* in the range 0 to 255.
|
||
|
*/
|
||
|
static function bytesToByte($bytes, $offset) {
|
||
|
return ord($bytes{$offset});
|
||
|
}
|
||
|
|
||
|
|
||
|
/**
|
||
|
* Extract a signed byte from bytes.
|
||
|
*
|
||
|
* @param string the bytes.
|
||
|
*
|
||
|
* @param int the offset. The byte found at the offset will be
|
||
|
* returned as an integer. The must be at least one byte available
|
||
|
* at offset.
|
||
|
*
|
||
|
* @return int the signed byte found at offset, e.g., an integer in
|
||
|
* the range -128 to 127.
|
||
|
*/
|
||
|
static function bytesToSByte($bytes, $offset) {
|
||
|
$n = self::bytesToByte($bytes, $offset);
|
||
|
if ($n > 127)
|
||
|
return $n - 256;
|
||
|
else
|
||
|
return $n;
|
||
|
}
|
||
|
|
||
|
|
||
|
/**
|
||
|
* Extract an unsigned short from bytes.
|
||
|
*
|
||
|
* @param string the bytes.
|
||
|
*
|
||
|
* @param int the offset. The short found at the offset will be
|
||
|
* returned as an integer. There must be at least two bytes
|
||
|
* available beginning at the offset given.
|
||
|
*
|
||
|
* @return int the unsigned short found at offset, e.g., an integer
|
||
|
* in the range 0 to 65535.
|
||
|
*
|
||
|
* @param PelByteOrder one of {@link LITTLE_ENDIAN} and {@link
|
||
|
* BIG_ENDIAN}.
|
||
|
*/
|
||
|
static function bytesToShort($bytes, $offset, $endian) {
|
||
|
if ($endian == self::LITTLE_ENDIAN)
|
||
|
return (ord($bytes{$offset+1}) * 256 +
|
||
|
ord($bytes{$offset}));
|
||
|
else
|
||
|
return (ord($bytes{$offset}) * 256 +
|
||
|
ord($bytes{$offset+1}));
|
||
|
}
|
||
|
|
||
|
|
||
|
/**
|
||
|
* Extract a signed short from bytes.
|
||
|
*
|
||
|
* @param string the bytes.
|
||
|
*
|
||
|
* @param int the offset. The short found at offset will be returned
|
||
|
* as an integer. There must be at least two bytes available
|
||
|
* beginning at the offset given.
|
||
|
*
|
||
|
* @return int the signed byte found at offset, e.g., an integer in
|
||
|
* the range -32768 to 32767.
|
||
|
*
|
||
|
* @param PelByteOrder one of {@link LITTLE_ENDIAN} and {@link
|
||
|
* BIG_ENDIAN}.
|
||
|
*/
|
||
|
static function bytesToSShort($bytes, $offset, $endian) {
|
||
|
$n = self::bytesToShort($bytes, $offset, $endian);
|
||
|
if ($n > 32767)
|
||
|
return $n - 65536;
|
||
|
else
|
||
|
return $n;
|
||
|
}
|
||
|
|
||
|
|
||
|
/**
|
||
|
* Extract an unsigned long from bytes.
|
||
|
*
|
||
|
* @param string the bytes.
|
||
|
*
|
||
|
* @param int the offset. The long found at offset will be returned
|
||
|
* as an integer. There must be at least four bytes available
|
||
|
* beginning at the offset given.
|
||
|
*
|
||
|
* @return int the unsigned long found at offset, e.g., an integer
|
||
|
* in the range 0 to 4294967295.
|
||
|
*
|
||
|
* @param PelByteOrder one of {@link LITTLE_ENDIAN} and {@link
|
||
|
* BIG_ENDIAN}.
|
||
|
*/
|
||
|
static function bytesToLong($bytes, $offset, $endian) {
|
||
|
if ($endian == self::LITTLE_ENDIAN)
|
||
|
return (ord($bytes{$offset+3}) * 16777216 +
|
||
|
ord($bytes{$offset+2}) * 65536 +
|
||
|
ord($bytes{$offset+1}) * 256 +
|
||
|
ord($bytes{$offset}));
|
||
|
else
|
||
|
return (ord($bytes{$offset}) * 16777216 +
|
||
|
ord($bytes{$offset+1}) * 65536 +
|
||
|
ord($bytes{$offset+2}) * 256 +
|
||
|
ord($bytes{$offset+3}));
|
||
|
}
|
||
|
|
||
|
|
||
|
/**
|
||
|
* Extract a signed long from bytes.
|
||
|
*
|
||
|
* @param string the bytes.
|
||
|
*
|
||
|
* @param int the offset. The long found at offset will be returned
|
||
|
* as an integer. There must be at least four bytes available
|
||
|
* beginning at the offset given.
|
||
|
*
|
||
|
* @return int the signed long found at offset, e.g., an integer in
|
||
|
* the range -2147483648 to 2147483647.
|
||
|
*
|
||
|
* @param PelByteOrder one of {@link LITTLE_ENDIAN} and {@link
|
||
|
* BIG_ENDIAN}.
|
||
|
*/
|
||
|
static function bytesToSLong($bytes, $offset, $endian) {
|
||
|
$n = self::bytesToLong($bytes, $offset, $endian);
|
||
|
if ($n > 2147483647)
|
||
|
return $n - 4294967296;
|
||
|
else
|
||
|
return $n;
|
||
|
}
|
||
|
|
||
|
|
||
|
/**
|
||
|
* Extract an unsigned rational from bytes.
|
||
|
*
|
||
|
* @param string the bytes.
|
||
|
*
|
||
|
* @param int the offset. The rational found at offset will be
|
||
|
* returned as an array. There must be at least eight bytes
|
||
|
* available beginning at the offset given.
|
||
|
*
|
||
|
* @return array the unsigned rational found at offset, e.g., an
|
||
|
* array with two integers in the range 0 to 4294967295.
|
||
|
*
|
||
|
* @param PelByteOrder one of {@link LITTLE_ENDIAN} and {@link
|
||
|
* BIG_ENDIAN}.
|
||
|
*/
|
||
|
static function bytesToRational($bytes, $offset, $endian) {
|
||
|
return array(self::bytesToLong($bytes, $offset, $endian),
|
||
|
self::bytesToLong($bytes, $offset+4, $endian));
|
||
|
}
|
||
|
|
||
|
|
||
|
/**
|
||
|
* Extract a signed rational from bytes.
|
||
|
*
|
||
|
* @param string the bytes.
|
||
|
*
|
||
|
* @param int the offset. The rational found at offset will be
|
||
|
* returned as an array. There must be at least eight bytes
|
||
|
* available beginning at the offset given.
|
||
|
*
|
||
|
* @return array the signed rational found at offset, e.g., an array
|
||
|
* with two integers in the range -2147483648 to 2147483647.
|
||
|
*
|
||
|
* @param PelByteOrder one of {@link LITTLE_ENDIAN} and {@link
|
||
|
* BIG_ENDIAN}.
|
||
|
*/
|
||
|
static function bytesToSRational($bytes, $offset, $endian) {
|
||
|
return array(self::bytesToSLong($bytes, $offset, $endian),
|
||
|
self::bytesToSLong($bytes, $offset+4, $endian));
|
||
|
}
|
||
|
|
||
|
|
||
|
/**
|
||
|
* Format bytes for dumping.
|
||
|
*
|
||
|
* This method is for debug output, it will format a string as a
|
||
|
* hexadecimal dump suitable for display on a terminal. The output
|
||
|
* is printed directly to standard out.
|
||
|
*
|
||
|
* @param string the bytes that will be dumped.
|
||
|
*
|
||
|
* @param int the maximum number of bytes to dump. If this is left
|
||
|
* out (or left to the default of 0), then the entire string will be
|
||
|
* dumped.
|
||
|
*/
|
||
|
static function bytesToDump($bytes, $max = 0) {
|
||
|
$s = strlen($bytes);
|
||
|
|
||
|
if ($max > 0)
|
||
|
$s = min($max, $s);
|
||
|
|
||
|
$line = 24;
|
||
|
|
||
|
for ($i = 0; $i < $s; $i++) {
|
||
|
printf('%02X ', ord($bytes{$i}));
|
||
|
|
||
|
if (($i+1) % $line == 0)
|
||
|
print("\n");
|
||
|
}
|
||
|
print("\n");
|
||
|
}
|
||
|
|
||
|
}
|
||
|
|
||
|
?>
|