Zlib
====

Legacy data compression library - Consider using zlib-ng instead

.. toctree::
   :maxdepth: 1
   :caption: Contents:

Overview
--------

`Zlib <https://zlib.net/>`_ is a general-purpose, lossless data-compression library. However, it is now considered legacy on Discoverer and clusters.

.. warning::
    We strongly recommend using :doc:`zlib-ng` with its compatibility mode (zlib-ng-compat) instead of zlib. 
    Zlib-ng-compat provides:

    * Drop-in replacement for zlib
    * Significant performance improvements through SIMD optimizations
    * Automatic CPU feature detection and optimization
    * Full API compatibility with zlib

To switch to zlib-ng-compat, simply load its module instead of zlib::

    $ module load zlib-ng-compat/<version>

Also, refer to the :doc:`zlib-ng` documentation for more details.

Available versions
------------------

To view available zlib versions::

    $ module load zlib

Build recipes and configuration details are maintained in our GitLab repository:

* `Build Recipes <https://gitlab.discoverer.bg/vkolev/recipes/-/tree/main/zlib>`_

Compiler support
----------------

Each zlib version is built against multiple compiler sets, though we recommend using :doc:`zlib-ng` instead.

Still supported builds (but soon to be retired)::

    $ module avail zlib/*/*llvm    # LLVM build
    $ module avail zlib/*/*gcc     # GCC build

Retired builds (but still available in the public software repository)::

    $ module avail zlib/*/*intel   # Intel oneAPI build
    $ module avail zlib/*/*nvidia  # NVIDIA HPC SDK build
    $ module avail zlib/*/*aocc    # AMD AOCC build

Migration to zlib-ng
--------------------

For dynamically linked programs::

    $ module load zlib-ng-compat/<version>
    $ ./your_program   # will automatically use libz.so from zlib-ng-compat installation

For programs requiring recompilation against the zlib-ng-compat library::

    $ module load zlib-ng-compat/<version>
    $ <compiler or linker> <flags> <source_files or object files> -lz

.. note::
    The zlib-ng-compat provides the same API and ABI as zlib, making it a safe replacement 
    with significant performance benefits through CPU-specific optimizations based on SIMD instructions.

Getting Help
------------

For additional assistance:

* See the :doc:`help` documentation