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Improve documentation for creation of MOBI header

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This commit is contained in:
Kovid Goyal 2009-05-29 12:32:08 -07:00
parent 60146aeb6f
commit 01b75a68a4
1 changed files with 103 additions and 14 deletions
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117
src/calibre/ebooks/mobi/writer.py
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@ -29,8 +29,6 @@ from calibre.ebooks.oeb.base import urlnormalize
from calibre.ebooks.compression.palmdoc import compress_doc
# TODO:
# - Allow override CSS (?)
# - Generate index records
# - Optionally rasterize tables
EXTH_CODES = {
@ -427,30 +425,121 @@ class MobiWriter(object):
metadata = self._oeb.metadata
exth = self._build_exth()
record0 = StringIO()
# The PalmDOC Header
record0.write(pack('>HHIHHHH', self._compression, 0,
self._text_length, self._text_nrecords, RECORD_SIZE, 0, 0))
self._text_length,
self._text_nrecords, RECORD_SIZE, 0, 0)) # 0 - 15 (0x0 - 0xf)
uid = random.randint(0, 0xffffffff)
title = str(metadata.title[0])
# The MOBI Header
# 0x0 - 0x3
record0.write('MOBI')
record0.write(pack('>IIIII', 0xe8, 2, 65001, uid, 6))
record0.write('\xff' * 40)
record0.write(pack('>I', self._text_nrecords + 1))
record0.write(pack('>II', 0xe8 + 16 + len(exth), len(title)))
record0.write(iana2mobi(str(metadata.language[0])))
# 0x4 - 0x7 : Length of header
# 0x8 - 0x11 : MOBI type
# type meaning
# 0x002 MOBI book (chapter - chapter navigation)
# 0x101 News - Hierarchical navigation with sections and articles
# 0x102 News feed - Flat navigation
# 0x103 News magazine - same as 1x101
# 0xC - 0xF : Text encoding (65001 is utf-8)
# 0x10 - 0x13 : UID
# 0x14 - 0x17 : Generator version
record0.write(pack('>IIIII',
0xe8, 2, 65001, uid, 6))
# 0x18 - 0x1f : Unknown
record0.write('\xff' * 8)
# 0x20 - 0x23 : Secondary index record
# TODO: implement
record0.write('\xff' * 4)
# 0x24 - 0x3f : Unknown
record0.write('\xff' * 28)
# 0x40 - 0x43 : Offset of first non-text record
record0.write(pack('>I',
self._text_nrecords + 1))
# 0x44 - 0x4b : title offset, title length
record0.write(pack('>II',
0xe8 + 16 + len(exth), len(title)))
# 0x4c - 0x4f : Language specifier
record0.write(iana2mobi(
str(metadata.language[0])))
# 0x50 - 0x57 : Unknown
record0.write('\0' * 8)
record0.write(pack('>II', 6, self._text_nrecords + 1))
# 0x58 - 0x5b : Format version
# 0x5c - 0x5f : First image record number
record0.write(pack('>II',
6, self._text_nrecords + 1))
# 0x60 - 0x63 : First HUFF/CDIC record number
# 0x64 - 0x67 : Number of HUFF/CDIC records
# 0x68 - 0x6b : First DATP record number
# 0x6c - 0x6f : Number of DATP records
record0.write('\0' * 16)
# 0x70 - 0x73 : EXTH flags
record0.write(pack('>I', 0x50))
# 0x74 - 0x93 : Unknown
record0.write('\0' * 32)
record0.write(pack('>IIII', 0xffffffff, 0xffffffff, 0, 0))
# 0x94 - 0x97 : DRM offset
# 0x98 - 0x9b : DRM count
# 0x9c - 0x9f : DRM size
# 0xa0 - 0xa3 : DRM flags
record0.write(pack('>IIII',
0xffffffff, 0xffffffff, 0, 0))
# 0xa4 - 0xaf : Unknown
record0.write('\0'*12)
# 0xb0 - 0xb1 : First content record number
# 0xb2 - 0xb3 : last content record number
# (Includes Image, DATP, HUFF, DRM)
# TODO: implement
record0.write(pack('>I', 0xffffffff))
# 0xb4 - 0xb7 : Unknown
record0.write('\0'*4)
# 0xb8 - 0xbb : FCIS record number
record0.write(pack('>I', 0xffffffff))
# 0xbc - 0xbf : Unknown (FCIS record count?)
record0.write(pack('>I', 0))
# 0xc0 - 0xc3 : FLIS record number
record0.write(pack('>I', 0xffffffff))
# 0xc4 - 0xc7 : Unknown (FLIS record count?)
record0.write(pack('>I', 0))
# 0xc8 - 0xcf : Unknown
record0.write('\0'*8)
# 0xd0 - 0xdf : Unknown
record0.write(pack('>IIII', 0xffffffff, 0, 0xffffffff, 0xffffffff))
# 0xe0 - 0xe3 : Extra record data
# The '5' is a bitmask of extra record data at the end:
# - 0x1: <extra multibyte bytes><size> (?)
# - 0x4: <uncrossable breaks><size>
# Of course, the formats aren't quite the same.
# TODO: What the hell are the rest of these fields?
record0.write(pack('>IIIIIIIIIIIIIIIII',
0, 0, 0, 0xffffffff, 0, 0xffffffff, 0, 0xffffffff, 0, 0xffffffff,
0, 0xffffffff, 0, 0xffffffff, 0xffffffff, 5, 0xffffffff))
record0.write(pack('>I', 5))
# 0xe4 - 0xe7 : Primary index record
# TODO: Implement
record0.write(pack('>I', 0xffffffff))
record0.write(exth)
record0.write(title)
record0 = record0.getvalue()