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Library for reading and writing NBT files, as used by Minecraft.
Ruby
Tag: nbtfile-0.1.0

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README.rdoc

nbtfile

NBTFile is a low-level library for reading and writing NBT-format files, as used by the popular game Minecraft.

Official Specification

The official (if somewhat confusing) specification for the NBT file format may be found at www.minecraft.net/docs/NBT.txt

Data Model

The NBT data model has ten different data types:

- 8-bit signed integers (Tag_Byte)
- 16-bit signed integers (Tag_Short)
- 32-bit signed integers (Tag_Int)
- 64-bit signed integers (Tag_Long)
- 32-bit floating-point numbers (Tag_Float)
- 64-bit floating-point numbers (Tag_Double)
- UTF-8 strings (Tag_String)
- raw byte strings (Tag_Byte_Array)
- homogenous lists (Tag_List)
- compound structures (Tag_Compound)

Compound structures (Tag_Compound) are unordered collections where each item (“tag”) has a name associated with it. Compound structures are heterogenous; the elements of a compound structure may be any mixture of types.

Lists (Tag_List) are ordered collections of unnamed items. Lists are homogenous; every element of a particular list must have the same type. Note that all lists have the same type (Tag_List) regardless of the type of their elements.

Items of an eleventh “type” (Tag_End) serve to terminate compound structures and lists (of any type). The wording of the official specification could permit lists of Tag_End, but this is not supported in practice.

The top level of an NBT file must be a single-element compound structure.

Syntax

NBT files are gzip-compressed; the structure of the uncompressed data can be described by the following ABNF (see RFC 5234).

nbt-data = tag-compound

tag-compound = TAG-COMPOUND name compound-body

compound-body = *tag TAG-END

tag = TAG-BYTE name byte /
      TAG-SHORT name short /
      TAG-INT name int /
      TAG-LONG name long /
      TAG-FLOAT name float /
      TAG-DOUBLE name double /
      TAG-STRING name string /
      TAG-BYTE-ARRAY name byte-array /
      TAG-LIST name list /
      tag-compound

name = string

list = TAG-BYTE list-length *byte /
       TAG-SHORT list-length *short /
       TAG-INT list-length *int /
       TAG-LONG list-length *long /
       TAG-FLOAT list-length *float /
       TAG-DOUBLE list-length *double /
       TAG-STRING list-length *string /
       TAG-BYTE-ARRAY list-length *byte-array /
       TAG-LIST list-length *list /
       TAG-COMPOUND list-length *compound-body

list-length = int

; see RFC 3629 for definition of UTF8-octets
string = string-length UTF8-octets

string-length = short

byte-array = byte-array-length *byte

byte-array-length = int

byte = OCTET ; 8-bit signed integer

short = 2OCTET ; 16-bit signed integer, big-endian

int = 4OCTET ; 32-bit signed integer, big-endian

long = 8OCTET ; 64-bit signed integer, big-endian

float = 4OCTET ; 32-bit float, big-endian, IEEE 754-2008

double = 8OCTET ; 64-bit float, big-endian, IEEE 754-2008

TAG-END = %x00
TAG-BYTE = %x01
TAG-SHORT = %x02
TAG-INT = %x03
TAG-LONG = %x04
TAG-FLOAT = %x05
TAG-DOUBLE = %x06
TAG-BYTE-ARRAY = %x07
TAG-STRING = %x08
TAG-LIST = %x09
TAG-COMPOUND = %x0a

Interface

Low-level API

NBTFile.tokenize

NBTFile.emit

High-level API

NBTFile.load

Note on Patches/Pull Requests

  • Fork the project.

  • Make your feature addition or bug fix.

  • Add tests for it. This is important so I don't break it in a future version unintentionally.

  • Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)

  • Send me a pull request. Bonus points for topic branches.

Copyright

Copyright © 2010 MenTaLguY. See LICENSE for details.

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