hdf5/doc/html/RM_H5Z.html
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HDF5/H5Z API Specification
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<h1>H5Z: Compression Interface</h1>
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<h2>Compression API Functions</h2>
This function enable the user to configure a new compression
method for the local environment.
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<li><a href="#Compression-Register">H5Zregister</a>
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<p>
HDF5 supports compression of raw data by compression methods
built into the library or defined by an application.
A compression method is associated with a dataset when the dataset is
created and is applied independently to each storage chunk of the dataset.
The dataset must use the <code>H5D_CHUNKED</code> storage layout.
<p>
The HDF5 library does not support compression for contiguous datasets
because of the difficulty of implementing random access for partial I/O.
Compact dataset compression is not supported because it would not produce
significant results.
<p>
See <a href="Datasets.html"><cite>The Dataset Interface (H5D)</cite></a>
in the <cite>HDF5 User's Guide</cite> for further information regarding
data compression.
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Compression-Register">H5Zregister</a>
<dt><strong>Signature:</strong>
<dd><em>herr_t</em> <code>H5Zregister</code>(<em>H5Z_method_t</em> <code>method</code>,
<em>const char *</em><code>name</code>,
<em>H5Z_func_t</em><code>cfunc</code>,
<em>H5Z_func_t</em> <code>ufunc</code>
)
<dt><strong>Purpose:</strong>
<dd> Registers new compression and uncompression functions for a
method specified by a method number.
<dt><strong>Description:</strong>
<dd><code>H5Zregister</code> registers new compression and uncompression
functions for a method specified by a method number, <code>method</code>.
<code>name</code> is used for debugging and may be the null pointer.
Either or both of <code>cfunc</code> (the compression function) and
<code>ufunc</code> (the uncompression method) may be null pointers.
<p>
The statistics associated with a method number are not reset
by this function; they accumulate over the life of the library.
<dt><strong>Parameters:</strong>
<dl>
<dt><em>H5Z_method_t</em> <code>method</code>
<dd>Number specifying compression method.
<dt><em>const char *</em><code>name</code>
<dd>Name associated with the method number.
<dt><em>H5Z_func_t</em> <code>cfunc</code>
<dd>Compression method.
<dt><em>H5Z_func_t</em> <code>ufunc</code>
<dd>Uncompression method.
</dl>
<dt><strong>Returns:</strong>
<dd>Returns a non-negative value if successful;
otherwise returns a negative value.
</dl>
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<a href="H5.intro.html">Introduction to HDF5</a>&nbsp;<br>
<a href="H5.user.html">HDF5 User Guide</a>&nbsp;<br>
<a href="index.html">Other HDF5 documents and links</a>&nbsp;<br>
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<td valign=top align=right>
And in this document, the
<a href="RM_H5Front.html">HDF5 Reference Manual</a>&nbsp;&nbsp;
<br>
<a href="RM_H5.html">H5</a>&nbsp;&nbsp;
<a href="RM_H5A.html">H5A</a>&nbsp;&nbsp;
<a href="RM_H5D.html">H5D</a>&nbsp;&nbsp;
<a href="RM_H5E.html">H5E</a>&nbsp;&nbsp;
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<a href="RM_H5G.html">H5G</a>&nbsp;&nbsp;
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<a href="RM_H5S.html">H5S</a>&nbsp;&nbsp;
<a href="RM_H5T.html">H5T</a>&nbsp;&nbsp;
H5Z&nbsp;&nbsp;
<a href="Tools.html">Tools</a>&nbsp;&nbsp;
<a href="PredefDTypes.html">Datatypes</a>&nbsp;&nbsp;
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<address>
<a href="mailto:hdfhelp@ncsa.uiuc.edu">HDF Help Desk</a>
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Last modified: 8 September 2000
<br>
Describes HDF5 Release 1.5, Unreleased Development Branch
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