Module lpack
Corona binding to lpack, a simple Lua library for packing and unpacking binary data.
local lpack = require("plugin.serialize").lpack
The library contains two functions: pack and unpack.
pack is called as follows: pack(F,x1,x2,...), where F is a string describing
how the values x1, x2, ... are to be interpreted and formatted. Each letter
in the format string F consumes one of the given values. Only values of type
number or string are accepted. pack returns a (binary) string containing the
values packed as described in F. The letter codes understood by pack are listed
below (they are inspired by Perl's codes but are not the same). Numbers
following letter codes in F indicate repetitions.
unpack is called as follows: unpack(s,F,[init]), where s is a (binary) string
containing data packed as if by pack, F is a format string describing what is
to be read from s, and the optional init marks where in s to begin reading the
values. unpack returns one value per letter in F until F or s is exhausted
(the letters codes are the same as for pack, except that numbers following 'A'
are interpreted as the number of characters to read into the string, not as
repetitions).
The first value returned by unpack is the next unread position in s, which can be used as the init position in a subsequent call to unpack. This allows you to unpack values in a loop or in several steps. If the position returned by unpack is beyond the end of s, then s has been exhausted; any calls to unpack starting beyond the end of s will always return nil values.
Notice in the original:
This code is hereby placed in the public domain. Please send comments, suggestions, and bug reports to lhf@tecgraf.puc-rio.br.
Codes
- z: zero-terminated string
- p: string preceded by length byte
- P: string preceded by length word
- a: string preceded by length size_t
- A: string
- f: float
- d: double
- n: Lua number
- c: char
- b: byte = unsigned char
- h: short
- H: unsigned short
- i: int
- I: unsigned int
- l: long
- L: unsigned long
- <: little endian
- >: big endian
- =: native endian
Functions
| pack (f, ...) | Packs values into string (see summary for more info) |
| unpack (s, f[, init]) | Unpacks values from a string (see summary for more info). |
Functions
- pack (f, ...)
-
Packs values into string (see summary for more info)
Parameters:
- f string Format string.
- ... Values to pack.
Returns:
-
string
Packed string.
- unpack (s, f[, init])
-
Unpacks values from a string (see summary for more info).
Parameters:
Returns:
- int Next unread position.
- Value(s) from string.