**********************************************************************
* Author : Brian Maher <maherb at brimworks dot com>
* Library : lua_zlib - Lua 5.1 interface to zlib
*
* The MIT License
*
* Copyright (c) 2009 Brian Maher
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
**********************************************************************
To use this library, you need zlib, get it here:
http://www.gzip.org/zlib/
To build this library, you can use CMake and get it here:
http://www.cmake.org/cmake/resources/software.html
...or you can use GNU Make.
make <platform>
Loading the library:
If you built the library as a loadable package
[local] zlib = require 'zlib'
If you compiled the package statically into your application, call
the function "luaopen_zlib(L)". It will create a table with the zlib
functions and leave it on the stack.
-- zlib functions --
major, minor, patch = zlib.version()
returns numeric zlib version for the major, minor, and patch
levels of the version dynamically linked in.
function stream = zlib.deflate([ int compression_level ])
If no compression_level is provided uses Z_DEFAULT_COMPRESSION (6),
compression level is a number from 1-9 where zlib.BEST_SPEED is 1
and zlib.BEST_COMPRESSION is 9.
Returns a "stream" function that compresses (or deflates) all
strings passed in. Specifically, use it as such:
string deflated, bool eof, number bytes_in number bytes_out =
stream(string input [, 'sync' | 'full' | 'finish'])
Takes input and deflates and returns a portion of it,
optionally forcing a flush.
A 'sync' flush will force all pending output to be flushed to
the return value and the output is aligned on a byte boundary,
so that the decompressor can get all input data available so
far. Flushing may degrade compression for some compression
algorithms and so it should be used only when necessary.
A 'full' flush will flush all output as with 'sync', and the
compression state is reset so that decompression can restart
from this point if previous compressed data has been damaged
or if random access is desired. Using Z_FULL_FLUSH too often
can seriously degrade the compression.
A 'finish' flush will force all pending output to be processed
and results in the stream become unusable. Any future
attempts to print anything other than the empty string will
result in an error that begins with IllegalState.
The eof result is true if 'finish' was specified, otherwise
it is false.
The bytes_in is how many bytes of input have been passed to
stream, and bytes_out is the number of bytes returned in
deflated string chunks.
stream = zlib.inflate([windowBits])
Returns a "stream" function that decompresses (or inflates) all
strings passed in. Optionally specify a windowBits argument
that is passed to inflateInit2(), see zlib.h for details about
this argument. By default, gzip header detection is done, and
the max window size is used.
The "stream" function should be used as such:
string inflated, bool eof, number bytes_in, number bytes_out = stream(string input)
Takes input and inflates and returns a portion of it. If it
detects the end of a deflation stream, then total will be the
total number of bytes read from input and all future calls to
stream() with a non empty string will result in an error that
begins with IllegalState.
No flush options are provided since the maximal amount of
input is always processed.
eof will be true when the input string is determined to be at
the "end of the file".
The bytes_in is how many bytes of input have been passed to
stream, and bytes_out is the number of bytes returned in
inflated string chunks.
init = zlib.adler32()
checksum = zlib.adler32(string input)
new checksum = zlib.adler32(partical string input, previous checksum)
new checksum = zlib.adler32(previous checksum, remain part checksum, remain part length)
init = zlib.crc32()
checksum = zlib.crc32(string input)
new checksum = zlib.crc32(partical string input, previous checksum)
new checksum = zlib.crc32(previous checksum, remain part checksum, remain part length)
these function used to compute the checksum of a string data.
there two algorithm of checksum, adler32 and crc32.
if you call the function without argument, it will give a
initial value used in partical mode.
if you call the function with a string, the checksum of this
string is returned.
if you call the function with a string and a preious checksum
(partical mode), the function will compute the checksum of the
string concated with preious string input (used to compute
preious checksum) and the new string input given in call. e.g.
assert(zlib.adler32 "onetwo" == zlib.adler32("two", zlib.adler32("one")))
and if you have both checksum of two part input, you can used
the combine mode: just pass the preious checksum, and the
checksum of new part, and the length of the new part. e.g.
assert(zlib.adler32 "onetwo" == zlib.adler32(
zlib.adler32 "one",
zlib.adler32 "two",
3 -- the length of second part "two"
))