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EBook-Tools-v0.5.4
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/ EBook::Tools::PalmDoc

NAME

EBook::Tools::PalmDoc - Palm::PDB handler for manipulating the PalmDoc/PilotDoc/AportisDoc format

SYNOPSIS

use EBook::Tools::PalmDoc qw(uncompress_palmdoc);
use Palm::PDB;

my $pdb = Palm::PDB->new();

or

use EBook::Tools::PalmDoc qw(:all);

my $pdb = EBook::Tools::PalmDoc->new();
$pdb->set_text($text);
$pdb->Write('textfile.pdb');

my $pdb2 = EBook::Tools::PalmDoc->new();
$pdb2->{attributes}{resource} = 1;
$pdb->import_textfile('textfile.txt');
$pdb->Write('textfile.prc');

DESCRIPTION

This module contains a Palm::PDB handler (subclassed from Palm::Raw) and some associated general procedures for dealing with PalmDoc books. This handles PalmDoc and only PalmDoc. For Mobipocket, eReader, or other .pdb/.prc formats, see the module specific to the format.

CONSTRUCTOR

new()

Instantiates a new Ebook::Tools::PalmDoc object. To create a Palm Resource file instead of a Palm Database file, set $self->{attributes}{resource} to be true immediately after construction.

Create a new Doc object. By default, it's not a resource database. Setting $self->{attributes}{resource} to 1 before any manipulations will cause it to become a resource database.

ACCESSOR METHODS

bookmarks()

Returns a hash of bookmarks, where the keys are the bookmark offsets and the values are the bookmark names.

text()

Returns the text of the file

html()

Returns the text of the file converted to HTML via HTML::TextToHTML.

MODIFIER METHODS

These methods have two naming/capitalization schemes -- methods directly related to the subclassing of Palm::PDB use its MethodName capitalization style. Any other methods are lowercase_with_underscores for consistency with the rest of EBook::Tools.

ParseRecord(%record)

Parses PDB records, updating the object attributes. This method is called automatically on every database record (in .pdb files) during Load().

ParseResource(%resource)

Parses PDB resources, updating object attributes. This is called automatically on every database resource (in .prc files) during Load().

ParseRecordBookmark($data,$currentrecord)

Parses bookmark records/resources, updating object attributes, most notably $self->{bookmarks}.

The $currentrecord argument is optional, but without it the debugging information may be less useful. This is called automatically by ParseRecord() and ParseResource() as needed.

ParseRecordText($data)

Parses text records, updating object attributes, most notably appending text to $self->{text}.

This is called automatically by "ParseRecord()" and "ParseResource()" as needed.

set_text(@text)

Uses the contents of @text (concatenated) as the text of the PDB.

import_textfile($filename)

Set the contents of the Doc to the contents of the file and sets the name of the PDB to the basename of the file.

PROCEDURES

All procedures are exportable, but none are exported by default.

compress_palmdoc($text)

Compresses input text using the simplified Lempel-Ziv 77 encoding used by PalmDoc and some other formats and returns the compressed string.

See "uncompress_palmdoc()" for more details on the algorithm.

This procedure was taken from Palm::Doc with some minor changes.

parse_palmdoc_header($data)

Takes as an argument a scalar containing the 16 bytes of the PalmDoc header (also used by Mobipocket). Returns a hashref containing those values keyed to recognizable names.

See:

http://wiki.mobileread.com/wiki/DOC#PalmDOC

and

http://wiki.mobileread.com/wiki/MOBI

keys

The returned hashref will have the following keys:

  • compression

    Possible values:

    1 - no compression
    2 - PalmDoc compression
    128 - iSilo3?
    17480 (the characters 'DH') - Mobipocket 'Dictionary Huffman' compression (aka HuffDic aka Huff/CDIC)

    A warning will be carped if an unknown value is found.

  • textlength

    Uncompressed length of book text in bytes

  • textrecords

    Number of PDB records used for book text

  • recordsize

    Maximum size of each record containing book text. This should always be 2048 (for some Mobipocket files) or 4096 (for everything else). A warning will be carped if it isn't.

  • spare

    Two bytes that should always be zero. A warning will be carped if they aren't.

  • unknown12

    32 bits of unknown data, generally zero. This key may be changed later if more information is discovered. Use with caution.

Note that the current position component of the header is discarded.

uncompress_palmdoc($data,%args)

Uncompresses data compressed using the simplified Lempel-Ziv 77 scheme used by PalmDoc and some other formats, and returns the uncompressed string.

If an error is encountered during uncompression outputs a debug message and returns undef.

Arguments

uncompress_palmdoc takes one optional named argument:

trailing

This specifies the number of trailing bytes to ignore on each record during decompression. Extra data such as this is sometimes found on version 6 Mobipocket records.

Algorithm

The decoding mechanism is as follows:

Start by reading a byte from the compressed stream. If the byte is:

  • 0x00: copy unmodified

  • 0x01 to 0x08: "Type A" command

    This specifies that the next 1-8 bytes are to be copied unmodified.

  • 0x09 to 0x7f: copy unmodified

  • 0x80 to 0xbf: "Type B" command

    This specifies that the 16 bits (two characters) starting at that point represent a length-offset pair. Of the 16 bits that make up these two bytes, the two leftmost bits (which should be '10') are simply an identifier and are discarded. The next 11 bits encode the offset backwards from the end of uncompressed text, and the last three encode the length of text to copy from that point (copying n+3 bytes).

  • 0xc0 to 0xff: "Type C" command

    This compresses spaces with the next character, with the value of that character being XORed with 0x80.

BUGS

  • There isn't really any good way to detect the encoding from a PalmDoc file, and I haven't even tried. You may have some luck with Encode::Detect. On top of this, the encodings aren't entirely conformant with what you might expect, and vary by version of PalmOS. See:

    http://www.df.lth.se/~triad/krad/recode/palm.html

    for details.

  • PalmDoc files in resource (.prc) form are almost entirely untested. Use at your own risk (but feel free to file bug reports).

  • Although bookmarks can be extracted, they cannot be added to a new file.

  • Unit tests are unwritten.

AUTHOR

Zed Pobre <zed@debian.org>

COPYRIGHT

Copyright 2008 Zed Pobre

Licensed to the public under the terms of the GNU GPL, version 2

SEE ALSO