Skip to content

global zlib

lzlib, by Tiago Dionizio.

Reference:

  • Old location: http://luaforge.net/projects/lzlib/.
  • More recent git repo (archived): https://github.com/LuaDist/lzlib
  • On luarocks: https://luarocks.org/modules/hisham/lzlib

😱 Types incomplete or incorrect? 🙏 Please contribute!

methods

zlib.version

function zlib.version() -> version string

@return version - For example 1.2.13

😱 Types incomplete or incorrect? 🙏 Please contribute!

Return the zlib version.

Example:

local version = zlib.version()
assert(version == '1.2.13')

Reference:

zlib.adler32

function zlib.adler32(
  adler32: number?,
  buffer: string?
) -> adler32 number

Return the initial adler32 value.

Call to update the adler32 value, adler32 is the current value, buffer is passed to adler32 zlib function and the updated value is returned.

This function is not related to compression but is exported anyway because it might be useful in applications using the compression library.

Example:

local adler = zlib.adler32()
assert(adler == 1.0)
adler = zlib.adler32(adler, 'some text')
assert(adler == 300417946.0)
adler = zlib.adler32(adler, 'some text')
assert(adler == 1144063795.0)
adler = zlib.adler32(adler, 'some text')
assert(adler == 2530937548.0)

Reference:

zlib.adler32

function zlib.adler32(
  crc32: number?,
  buffer: string?
) -> crc32 number

Return the initial crc32 (Cyclic Redundancy Check) value.

Call to update the crc32 value, crc32 is the current value, buffer is passed to crc32 zlib function and the updated value is returned.

This function is not related to compression but is exported anyway because it might be useful in applications using the compression library.

Example:

local crc = zlib.crc32()
assert(crc == 0.0)
crc = zlib.crc32(crc, 'some text')
assert(crc == 1337638330.0)
crc = zlib.crc32(crc, 'some text')
assert(crc == 2768805016.0)
crc = zlib.crc32(crc, 'some text')
assert(crc == 1021719064.0)

Reference:

zlib.compress

function zlib.compress(
  buffer: string,
  level: integer?,
  method: integer?,
  window_bits: integer?,
  mem_level: sub<integer,default>?,
  strategy: sub<integer,default>?
) -> buffer string
@param level - The compression level must be -1 (default compression), or between 0 and 9: 1 gives best speed, 9 gives best compression, 0 gives no compression at all (the input data is simply copied a block at a time).

@param method - The method parameter is the compression method. It must be 8 (Z_DEFLATED) in this version of the library.

@param window_bits - The window_bits parameter is the base two logarithm of the maximum window size (the size of the history buffer). It should be in the range 8..15 for this version of the library, default 15.

@param mem_level - 8

@param strategy - Z_DEFAULT_STRATEGY

Return a string containing the compressed buffer according to the given parameters.

Example:

local orig = [[
Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam
nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat,
sed diam voluptua.
]]
assert(string.len(zlib.compress(orig)) < string.len(orig))

Reference:

zlib.decompress

function zlib.decompress(
  buffer: string,
  window_bits: integer?
) ->  string
@param window_bits - The window_bits parameter is the base two logarithm of the maximum window size (the size of the history buffer). It should be in the range 8..15 for this version of the library, default 15.

Return the decompressed stream after processing the given buffer.

Example:

local uncompressed = 'Lorem ipsum'
local compressed = zlib.compress(uncompressed)
local result = zlib.decompress(compressed)
assert(result == uncompressed)

Reference:

zlib.compressobj

function zlib.compressobj(
  level: integer?,
  method: integer?,
  window_bits: integer?,
  mem_level: sub<integer,default>?,
  strategy: sub<integer,default>?
) ->  ZStream {
    adlerreset = function,
    compress = function,
    decompress = function,
    flush = function,
    close = function,
    adler = function,
}
@param level - The compression level must be -1 (default compression), or between 0 and 9: 1 gives best speed, 9 gives best compression, 0 gives no compression at all (the input data is simply copied a block at a time).

@param method - The method parameter is the compression method. It must be 8 (Z_DEFLATED) in this version of the library.

@param window_bits - The window_bits parameter is the base two logarithm of the maximum window size (the size of the history buffer). It should be in the range 8..15 for this version of the library, default 15.

@param mem_level - 8

@param strategy - Z_DEFAULT_STRATEGY

Return a deflate stream.

In the upstream project this function is called zlib.deflate().

Example:

local z_stream = zlib.compressobj(1)
local result = z_stream:compress('test')
assert(type(result) == 'string')

Reference:

zlib.decompressobj

function zlib.decompressobj(window_bits: integer?) ->  ZStream {
    adlerreset = function,
    compress = function,
    decompress = function,
    flush = function,
    close = function,
    adler = function,
}
@param window_bits - The window_bits parameter is the base two logarithm of the maximum window size (the size of the history buffer). It should be in the range 8..15 for this version of the library, default 15.

Return an inflate stream.

In the upstream project this function is called zlib.inflate().

Example:

local z_stream_com = zlib.compressobj(1)
local compressed = z_stream_com:compress('test')
compressed = compressed .. z_stream_com:flush()

local z_stream_decomp = zlib.decompressobj()
local result = z_stream_decomp:decompress(compressed)
assert(result == 'test')

Reference: