mini_gzip - embeddable, minimal, in-memory GZIP API
Embeddable, minimal GZIP functionality, with API designed to work from memory. Only supports decompression for now.
I wrote it when I needed a small piece of code to give me decompression in
an embedded system I was working with, and I found out that most of the
GZIP-related programs use POSIX FILE API, which made the examples not work
for my case.
The mini_gzip is based on miniz library
(https://code.google.com/p/miniz/), which provides an API for operating on
data compressed according to deflate algorithm. Added is a layer which
provides a container for the GZIP files and let me do some verification.
To build
Everything should be fairly self-contained, and built with:
make
How to use
The API operates on struct mini_gzip structures, which are containers for
the memory with GZIPed data. You must call mini_gz_init() on the structure
1st for the rest of the API to work correctly. Next, you must call
mini_gz_start(&gz, mem_in, size), where gz is the initialized container
and with GZIPed data pointed by mem_in of the size of size. To unpack,
you call mini_gz_unpack(&gz, mem_out, memsize), where the first argument
is the initialized container, the second mem_out is a pointer to the
output memory, and memsize is its lenght. It's important to have enough
bytes in the output buffer for decompressed data.
To test
Simple test is provided:
make test
To test by yourself, you can do:
wk:/w/repos/mini_gzip> ls -la miniz.o
-rw-r--r-- 1 wk staff 114348 20 paź 09:46 miniz.o
wk:/w/repos/mini_gzip> md5 miniz.o
MD5 (miniz.o) = e6199aade2020b6040fa160baee47d68
wk:/w/repos/mini_gzip> gzip miniz.o
wk:/w/repos/mini_gzip> ls -la miniz.o.gz
-rw-r--r-- 1 wk staff 44965 20 paź 09:46 miniz.o.gz
wk:/w/repos/mini_gzip> ./mini_gzip miniz.o.gz miniz.o
flag_c: 0 is_gzipped: 1
in_fn: miniz.o.gz out_fn: miniz.o level 6
--- testing decompression --
out_len = 114348
ret = 114348
wk:/w/repos/mini_gzip> md5 miniz.o
MD5 (miniz.o) = e6199aade2020b6040fa160baee47d68References
After publishing mini_gzip on HackerNews, byuu (http://byuu.org/) mentioned he has much leaner implementation of GZIP:
- https://gitlab.com/higan/higan/blob/master/nall/decode/gzip.hpp
- https://gitlab.com/higan/higan/blob/master/nall/decode/inflate.hpp
Author
- Wojciech Adam Koszek, [email protected]
- http://www.koszek.com