Implementation of Zlib and GZip in OCaml






v1.4.2 2021-08-02 Paris (France)

  • Fix lower bounds of cmdliner (@kit-ty-kate, #130)

  • Fix big-endian support (@dinosaure, @talex5, #131)

v1.4.1 2021-05-11 Paris (France)

  • Fix and of file and end of block op-code (@dinosaure, #123)
    breaking changes
    Semantically, the module De has another behavior about the inflation.
    Previously, the stream inflation was smart enough to recognize the end
    of the stream and the user did not need to really emit:
    De.Inf.src decoder empty 0 0 to say the end of the stream. Now, such
    call is required to notice to De.Inf the end of the stream. By this
    way, we are able to terminate the inflation correctly and we still
    continue to raise an error for unterminated stream
    (see tests/invalid_distance_code).

    For Zl/Gz users, this update does not imply anything when these
    implementations take care about such detail. Only De users should update
    their code to really emit the end of the stream with
    De.Inf.src decoder empty 0 0. In the PR, the diff show how to upgrade such

  • Upgrade decompress to optint.0.1.0 (@samoht, @dinosaure, #124)

  • Fix compilation of benchmarks (@dinosaure, #128)

  • Fix out of bounds errors on the non-stream implementation (@clecat,
    @ewanmellor, @dinosaure, #126, #127)

  • Optimize memcpy used on the non-stream implementation (@clecat,
    @dinosaure, #129)

v1.4.0 2021-04-22 Paris (France)

  • Add a well-know limitation about the encoding on the documentation, the
    output buffer must be upper than 2 bytes in any cases.
    (@dinosaure, #114)

  • Improve the documentation
    (@dinosaure, @brendanlong, #115)

  • breaking changes, the type of the window used to deflate according
    RFC 1951 was updated to De.Lz77.window
    (@dinosaure, #116 & #115)

  • Fix a bug when we want to add the EOB op-code into the queue. The deflation
    takes care about that. Note that the queue must be larger than 2.
    (@dinosaure, @kluvin, #117)

  • Improve the documentation a bit
    (@mseri, @dinosaure, #119)

  • Fix the use of optint and how we handle large files with Gz. Fix an error
    when we encode the isize into the deflated stream.
    (@dinosaure, @igarnier, #121 & #120)

  • Add a non-stream implementation (@clecat, @dinosaure, #102 & #92)

    The non-blocking stream API has a cost to maintain a state across syscall
    such as read and write. It's useful when we want to plug decompress
    behind something like a socket and care about memory-consumption but it has
    a big cost when we want to compress/decompress an object saved into one and
    unique buffer.

    The non-stream API gives an opportunity to inflate/deflate one and unique
    buffer without the usual plumbing required by the non-blocking stream API.
    However, we are limited to compute only objects which can fit into a

    About performance, the non-stream API is better than the non-blocking stream
    API. See the PR for more details about performances. On the
    book2 (from the Calgary corpus) file:

    • decompress (stream):
      15 Mb/s (deflation), 76 Mb/s (inflation), ratio: 42.46 %

    • decompress (non-stream):
      17 Mb/s (deflation), 105 Mb/s (inflation), ratio: 34.66 %

    Even if we checked the implementation with our tests (we ran ocaml-git and
    irmin with this path), the implementation is young and we probably miss
    some details/bugs. So we advise the user to compare, at least, the non-stream
    implementation with the non-blocking stream implementation if something is

v1.3.0 2020-03-03 Paris (France)

  • Add a little executable to benchmark inflation into the distribution (@dinosaure, #93)

  • Add instructions for running benchmark (@gs0510, #94)

  • Clarify the description (@XVilka, #96)

  • Improve the benchmark and outputs (@dinosaure, @gs0510, #95)

  • Avoid allocation of distance table (@Engil, @dinosaure, #97)

  • Swapping from arithmetic to logical bitshifts on d.hold (@clecat, #99)

  • Make the use of all Higher.compress arguments (@vect0r-vicall, #103)

  • Apply ocamlformat.0.16.0 (@dinosaure, #105, #107)

  • Improve Lz77 algorithms (@dinosaure, #108)
    breaking changes the deflation expects a new window: De.Lz77.make_window
    instead of De.make_window (which is twice larger to improve the compression

    Depending on the level and your corpus, we did not observe performance
    regression on deflation (and #97 improves a lot performances). An higher level
    is slower (but the compression ratio is better). We advise, by default, to use
    the level 6.

    Note that the user is able to make its own compression algorithm according to
    his corpus. An example of such implementation is available on the new
    decompress.lz libraries which fills a queue and compress the input.

    breaking changes decompress expects a level between 0 and 9 (inclusive)
    (instead of 0 and 3).

  • Add tests about level compression (@dinosaure, #109)

  • Add level on GZip layer (@dinosaure, #110)

  • Provide a ctypes reverse binding (@dinosaure, #98)

  • Provide a binary decompress.pipe which can compress/uncompress with
    deflate, zlib or gzip format.

v1.2.0 2020-07-07 Paris (France)

  • add LZO support (@dinosaure, @cfcs, @XVilka, #82)

  • update binaries (@dinosaure, @XVilka, #89)

  • fix an exception leak (@dinosaure, @b1gtang, #88)

  • update (@dinosaure, @XVilka, #87)

  • fix a mis-use of Zl API (@dinosaure, #85)

  • add dune as a dependency of rfc1951 (@kit-ty-kate)

  • real non-blocking state with Zl (@dinosaure, #84)

v1.1.0 2019-03-10 Paris (France)

  • add GZip support (@dinosaure, @copy, @hcarty, #79)

  • breaking changes, Higher returns a result value instead to raise an exception (@dinosaure, @copy, #80)

  • protect Zlib decoder on multiple no-op calls of decode

  • test when we generate an empty zlib flow

  • fix a bug on the DEFLATE layer when we must flush bits to avoid integer overflow

  • really use the internal continuation of the Zlib state

  • delete fmt depedency

  • update fuzzer

  • fix default level on Zl.Higher

v1.0.0 2019-08-30 Paris (France)

** breaking changes **

decompress.1.0.0 is 3 times faster about decompression than before. A huge
amount of work was done to improve performance and coverage.

The main reason to update the API is to fix a bad design decision regarding split
compression and encoding. User is able to implement a new compression algorithm
and use it.

Release comes with regressions:

  • decompress only supports Bigarray now, not Bytes

  • GZIP layer does not exist anymore

  • state of RFC1951 encoder/decoder is not referentially transparent anymore

Of course, v1.0.0 comes with fixes and improvements:

  • decompress is able to compress/uncompress Calgary corpus

  • tests are improved and they include all coverage tests from zlib

  • compression algorithm has a fuzzer

  • encoder has a fuzzer

  • performance about decoder is 3 times better than decompress.v0.9.0 and 3
    times slower than zlib

decompress is split into 2 main modules:

  • dd which implements RFC1951

  • zz which implements ZLIB

API of them are pretty-close to what decompress.v0.9.0 does with some
advantages on dd:

  • User can use their own compression algorithm instead of Dd.L

  • encoder exposes more granular control over what it emits (which block, when, where)

  • Huffman tree generation is out of dd

As a response to #25, dd provides a higher level API resembling camlzip.

v0.9.0 2019-07-10 Paris (France)

  • Add support of 4.07 and 4.08 in Travis (@XVilka, @dinosaure, #70, #71)

  • Use mmap (@XVilka, @dinosaure, @hannesm, #68, #69, #71)

  • Update documentation (@yurug, @dinosaure, #65, #66)

  • Micro-optimization about specialization (@dinosaure, #64)

  • Re-organize internals of decompress (@dinosaure, #63)

  • GZIP support (@clecat, review by @dinosaure, @cfcs, @hannesm, #60)

  • fix #58 (@dinosaure)

v0.8.1 2018-10-16 Paris (France)

  • Dunify project (@dinosaure)

  • breaking-change Unbox Bytes.t and Bigstring.t as I/O buffer (@dinosaure)

  • Add foreign tests vectors (@cfcs, @dinosaure)

  • Catch invalid distance (@XVilka, @dinosaure)

  • Better check on dictionaries (@XVilka, @dinosaure)

  • breaking-change Add [wbits] argument to check Window size on RFC1951 (@XVilka, @dinosaure)

v0.8 2018-07-09 Paris (France)

  • Implementation of RFC1951 (task from @cfcs)

  • breaking change New interface of decompress

    We wrap API in Zlib_{inflate/deflate} and add RFC1951_{inflate/deflate}.

  • Move to jbuilder/dune (task from @samoht)

  • Better check on zlib header

  • Fixed infinite loop (task fron @cfcs)

    See 2e3af68, decompress has an infinite loop when the inflated dictionary
    does not provide any bindings (and length of opcode is <= 0). In this case,
    decompress expects an empty input and provide an empty output in any case.

  • Use re.1.7.2 on tests

  • Use camlzip.1.07 on tests

v0.7 2017-10-18 Paris (France)

  • Fixed Inflate.write function

  • Fixed internal state to stick in a internal final state

  • Fixed compilation with js_of_ocaml (use trampoline function to avoid

  • Fixed clash of name about state variable in the Inflate module

  • Add afl program

  • Export Adler-32 modules

  • Add -i and -o option in the dpipe binary to inform the size of the
    internal chunk

  • Change the value of -mode in the dpipe binary

v0.6 2017-05-11 Cao Lãnh (Vietnam)

  • Fixed bug #29

  • Produce far pattern (Lz77 compression)

  • Optimize memory consumption of the Inflate module

  • Move repository from oklm-wsh to mirage

  • Learn topkg release

v0.5 2017-02-17 Essaouira (Maroc)

  • Stabilize the interface (@dbuenzli's interface)

  • Merge optimization from @yallop

  • Add sync_flush, partial_flush, full_flush (experimental)

  • Move the build system to topkg