voxelcore/doc/en/scripting/builtins/libbyteutil.md

byteutil library

The library provides functions for working with byte arrays represented as tables or Bytearrays.

byteutil.pack(format: str, ...) -> Bytearray
byteutil.tpack(format: str, ...) -> table

Returns a byte array containing the provided values packed according to the format string. The arguments must exactly match the values required by the format.

The format string consists of special characters and value characters.

Special characters specify the byte order for the subsequent values:

Character	Byte Order
@	System
=	System
<	Little-endian
>	Big-endian
!	Network (big-endian)

Value characters describe the type and size.

Character	C++ Equivalent	Lua Type	Size
b	int8_t	number	1 byte
B	uint8_t	number	1 byte
?	bool	boolean	1 byte
h	int16_t	number	2 bytes
H	uint16_t	number	2 bytes
i	int32_t	number	4 bytes
I	uint32_t	number	4 bytes
f	float32_t	number	4 bytes
l	int64_t	number	8 bytes
L	uint64_t	number	8 bytes
d	float64_t	number	8 bytes

Warning

Due to the absence of an integer type in Lua for values l and L, only an output size of 8 bytes is guaranteed; the value may differ from what is expected.

byteutil.unpack(format: str, bytes: table|Bytearray) -> ...

Extracts values ​​from a byte array based on a format string.

Example:

debug.print(byteutil.tpack('>iBH?', -8, 250, 2019, true))
-- outputs:
-- debug.print(
--  {
--    255,
--    255,
--    255,
--    248,
--    250,
--    7,
--    227,
--    1
--  }
-- )

local bytes = byteutil.pack('>iBH?', -8, 250, 2019, true)
print(byteutil.unpack('>iBH?', bytes))
-- outputs:
--  -8      250     2019    true