mirror of
https://github.com/cshepherd/yagsdisasm.git
synced 2024-12-10 12:50:29 +00:00
233 lines
5.9 KiB
PHP
233 lines
5.9 KiB
PHP
<?php
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/**
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* Input_2MG - YAGSDisasm Input block device for .2MG image files
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* from http://apple2.org.za/gswv/a2zine/Docs/DiskImage_2MG_Info.txt
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*
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*/
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class Input_2MG
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{
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// have we been initialized yet?
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private $is_initialized = false;
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// source filename
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private $source_filename;
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// creator_id
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private $creator_id;
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// 2mg comment
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private $comment = '';
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// number of 512-byte blocks in image
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private $total_blocks;
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// header length
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private $header_length;
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// version number
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private $version_number;
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// image format
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private $image_format;
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// disk is locked?
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private $is_locked=false;
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// offset to image data
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private $image_offset;
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// DOS 3.3 Volume Number
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private $volume_number;
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// volume length in bytes
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private $total_bytes;
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// offset to comment
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private $comment_offset;
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// length of comment
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private $comment_length;
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// 2MG Creator data offset
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private $creator_data_offset;
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// 2MG Creator data length
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private $creator_data_length;
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// our file descriptor
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private $fp;
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public function __construct( $filename )
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{
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$fp = fopen( $filename, 'r' );
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if( !$fp )
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{
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throw new Exception( 'Input_2MG: Unable to open source file '.$filename );
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}
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$this->source_filename = $filename;
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// check for 2MG magic
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$magic = fread( $fp, 4 );
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if( $magic != '2IMG' )
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{
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throw new Exception( 'Input_2MG: source file not a 2MG file' );
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}
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// save creator id
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$this->creator_id = fread( $fp, 4 );
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// get header length (little-endian)
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$byte1 = fread( $fp, 1 );
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$byte2 = fread( $fp, 1 );
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$this->header_length = (ord( $byte2 )*256) + ord( $byte1 );
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// get version number (little-endian)
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$byte1 = fread( $fp, 1 );
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$byte2 = fread( $fp, 1 );
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$this->version_number = (ord( $byte2 )*256) + ord( $byte1 );
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// get image format (little-endian)
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$byte1 = fread( $fp, 1 );
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$byte2 = fread( $fp, 1 );
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$byte3 = fread( $fp, 1 );
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$byte4 = fread( $fp, 1 );
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$image_format_id = (ord( $byte4 )*16777216) + (ord( $byte3 )*65536) + (ord( $byte2 )*256) + ord( $byte1 );
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$known_format_ids = array(
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0 => 'DOS 3.3',
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1 => 'ProDOS',
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2 => 'NIB',
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);
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$this->image_format = $known_format_ids[$image_format_id];
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// flags / volume number (little-endian)
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$byte1 = fread( $fp, 1 );
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$byte2 = fread( $fp, 1 );
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$byte3 = fread( $fp, 1 );
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$byte4 = fread( $fp, 1 );
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if( ord( $byte2 ) && 0x01 )
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{
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$this->volume_number = ord( $byte1 );
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} else {
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if( $image_format_id == 1 )
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{
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$this->volume_number = 254;
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}
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}
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if( ord( $byte4 ) && 0x80 )
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{
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$this->is_locked = true;
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} else {
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$this->is_locked = false;
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}
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// block count (little-endian)
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$byte1 = fread( $fp, 1 );
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$byte2 = fread( $fp, 1 );
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$byte3 = fread( $fp, 1 );
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$byte4 = fread( $fp, 1 );
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$this->total_blocks = (ord( $byte4 )*16777216) + (ord( $byte3 )*65536) + (ord( $byte2 )*256) + ord( $byte1 );
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// offset to image data (little-endian)
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$byte1 = fread( $fp, 1 );
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$byte2 = fread( $fp, 1 );
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$byte3 = fread( $fp, 1 );
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$byte4 = fread( $fp, 1 );
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$this->image_offset = (ord( $byte4 )*16777216) + (ord( $byte3 )*65536) + (ord( $byte2 )*256) + ord( $byte1 );
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// bytes of disk data (little-endian)
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$byte1 = fread( $fp, 1 );
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$byte2 = fread( $fp, 1 );
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$byte3 = fread( $fp, 1 );
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$byte4 = fread( $fp, 1 );
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$this->total_bytes = (ord( $byte4 )*16777216) + (ord( $byte3 )*65536) + (ord( $byte2 )*256) + ord( $byte1 );
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// offset to comment (little-endian)
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$byte1 = fread( $fp, 1 );
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$byte2 = fread( $fp, 1 );
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$byte3 = fread( $fp, 1 );
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$byte4 = fread( $fp, 1 );
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$this->comment_offset = (ord( $byte4 )*16777216) + (ord( $byte3 )*65536) + (ord( $byte2 )*256) + ord( $byte1 );
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// comment length (little-endian)
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$byte1 = fread( $fp, 1 );
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$byte2 = fread( $fp, 1 );
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$byte3 = fread( $fp, 1 );
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$byte4 = fread( $fp, 1 );
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$this->comment_length = (ord( $byte4 )*16777216) + (ord( $byte3 )*65536) + (ord( $byte2 )*256) + ord( $byte1 );
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// creator data offset (little-endian)
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$byte1 = fread( $fp, 1 );
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$byte2 = fread( $fp, 1 );
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$byte3 = fread( $fp, 1 );
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$byte4 = fread( $fp, 1 );
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$this->creator_data_offset = (ord( $byte4 )*16777216) + (ord( $byte3 )*65536) + (ord( $byte2 )*256) + ord( $byte1 );
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// creator data length (little-endian)
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$byte1 = fread( $fp, 1 );
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$byte2 = fread( $fp, 1 );
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$byte3 = fread( $fp, 1 );
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$byte4 = fread( $fp, 1 );
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$this->creator_data_length = (ord( $byte4 )*16777216) + (ord( $byte3 )*65536) + (ord( $byte2 )*256) + ord( $byte1 );
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// reserved bytes
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$reserved = fread( $fp, 8 );
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// get Comment string if present
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if( $this->comment_length > 0 )
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{
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fseek( $fp, $this->comment_offset, SEEK_SET );
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$this->comment = fread( $fp, $this->comment_length );
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}
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$this->is_initialized = true;
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$this->fp = $fp;
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}
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/**
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* getBlocks( $starting_block, $num_blocks ) - Retrieve $num_blocks 512-byte blocks from the file, starting at $starting_block
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* @param $starting_block int, $num_blocks int
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* @return $data str
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*/
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public function getBlocks( $starting_block, $num_blocks )
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{
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fseek( $this->fp, $this->image_offset, SEEK_SET );
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fseek( $this->fp, $starting_block*512, SEEK_CUR );
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$data = '';
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for( $blk=0;$blk<$num_blocks;$blk++ )
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{
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$data .= fread( $this->fp, 512 );
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}
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return $data;
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}
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/**
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* printInfo() - Print some information about this 2MG image
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*/
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public function printInfo()
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{
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echo "Source Filename: ".$this->source_filename."\n";
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echo " Creator ID: ".$this->creator_id."\n";
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echo " Header Length: ".$this->header_length."\n";
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echo " Version Number: ".$this->version_number."\n";
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echo " Image Format: ".$this->image_format."\n";
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if( $this->image_format == 'DOS 3.3' )
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{
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echo " Volume Number: ".$this->volume_number."\n";
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}
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echo " Is Locked? ";
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if( $this->is_locked )
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{
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echo "Yes\n";
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} else {
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echo "No\n";
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}
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echo " Block Count: ".$this->total_blocks."\n";
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echo " Total Bytes: ".$this->total_bytes."\n";
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if( $this->comment != '' )
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{
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echo " Comment: ".$this->comment."\n";
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}
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}
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} |