imported>Drainedsoul |
imported>Fenhl |
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| All data sent over the network is [http://en.wikipedia.org/wiki/Endianness#Big-endian big-endian], that is the bytes are sent from most significant byte to least significant byte. The majority of everyday computers are little-endian, therefore it may be necessary to change the endianness before sending data over the network.
| | #REDIRECT [[Data types]] |
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| Other than 'String' and 'Metadata', which are decoded with a custom function, these data formats are identical to those provided by the Java classes [http://download.oracle.com/javase/1.4.2/docs/api/java/io/DataInputStream.html DataInputStream] and [http://download.oracle.com/javase/1.4.2/docs/api/java/io/DataOutputStream.html DataOutputStream].
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| {| class="wikitable"
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| |- class="row0"
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| | class="col0" |
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| ! class="col1" | Size
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| ! class="col2" | Range
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| ! class="col3" | Notes
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| |- class="row1"
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| ! class="col0 centeralign" | bool
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| | class="col1 centeralign" | 1
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| | class="col2" | 0 or 1
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| | class="col3" | Value can be either true (0x01) or false (0x00)
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| |- class="row2"
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| ! class="col0 centeralign" | byte
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| | class="col1 centeralign" | 1
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| | class="col2" | -128 to 127
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| | class="col3" | Signed, two's complement
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| |- class="row3"
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| ! class="col0 centeralign" | short
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| | class="col1 centeralign" | 2
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| | class="col2" | -32768 to 32767
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| | class="col3" | Signed, two's complement
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| |- class="row4"
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| ! class="col0 centeralign" | int
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| | class="col1 centeralign" | 4
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| | class="col2" | -2147483648 to 2147483647
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| | class="col3" | Signed, two's complement
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| |- class="row5"
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| ! class="col0 centeralign" | long
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| | class="col1 centeralign" | 8
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| | class="col2" | -9223372036854775808 to 9223372036854775807
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| | class="col3" | Signed, two's complement
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| |- class="row8"
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| ! class="col0 centeralign" | 128-bit integer
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| | class="col1 centeralign" | 16
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| | class="col2" | 0 to 340282366920938463463374607431768211455
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| | class="col3" | Unsigned, two's complement
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| Used in [http://wiki.vg/Protocol#Entity_Properties_.280x2C.29 0x2C] to transmit UUIDs.
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| The vanilla Minecraft server internally sends this as two longs.
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| |- class="row7"
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| ! class="col0 centeralign" | float
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| | class="col1 centeralign" | 4
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| | class="col2" |
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| See [http://java.sun.com/docs/books/jls/third_edition/html/typesValues.html#4.2.3 this]
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| | class="col3" | Single-precision 32-bit IEEE 754 floating point
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| |- class="row8"
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| ! class="col0 centeralign" | double
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| | class="col1 centeralign" | 8
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| | class="col2" |
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| See [http://java.sun.com/docs/books/jls/third_edition/html/typesValues.html#4.2.3 this]
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| | class="col3" | Double-precision 64-bit IEEE 754 floating point
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| |- class="row9"
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| ! class="col0 centeralign" | string
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| | class="col1 centeralign" | ≥ 2 <br />≤ 240
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| | class="col2" | N/A
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| | class="col3" | [http://en.wikipedia.org/wiki/UTF-16 UTF-16] big-endian string prefixed by a short containing the length of the string in code units.
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| UTF-16 is a variable-length encoding, which means that a single Unicode code point (what most programmers think of as a "character") may be encoded by a variable number of code units.
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| UTF-16 encodes code points as either one or two 16 bit code units.
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| Characters in the Basic Multilingual Plane (U+0000 through U+FFFF inclusive) are encoded as one 16 bit code unit.
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| Characters in the other Unicode planes (U+10000 through U+10FFFF inclusive) are encoded as two 16 bit code units (a high/low "surrogate pair").
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| Therefore, the length in bytes of a string may be obtained by multiplying the number of code units by two, and the opposite operation may be performed by dividing by two.
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| However, since UTF-16 is variable-length, the number of code units is totally unrelated to the number of code points (i.e. "characters"), and you will actually have to decode the string to obtain this information.
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| It was historically believed that the Minecraft protocol used the fixed-width encoding UCS-2, however this has since been proven to be incorrect.
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| |- class="row9"
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| ! class="col0 centeralign" | metadata
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| | class="col1 centeralign" | Varies
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| | class="col2" | See [[Entities#Entity_Metadata_Format|this]]
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| | class="Col3" |
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| |}
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| Some data may be stored as an "absolute integer", which is a more precise kind of integer, and a less precise kind of double. The conversion from double to absolute integer is like so:
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| abs_int = (int)double * 32;
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| And back again:
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| double = (double)abs_int / 32;
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| [[Category:Protocol Details]]
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| [[Category:Minecraft Modern]] | |