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-rw-r--r--doc/html/RM_H5Z.html172
1 files changed, 138 insertions, 34 deletions
diff --git a/doc/html/RM_H5Z.html b/doc/html/RM_H5Z.html
index e53146c..333d394 100644
--- a/doc/html/RM_H5Z.html
+++ b/doc/html/RM_H5Z.html
@@ -44,32 +44,52 @@ And in this document, the
</center>
<hr>
<!-- #EndLibraryItem --><center>
-<h1>H5Z: Compression Interface</h1>
+<h1>H5Z: Filter and Compression Interface</h1>
</center>
-<h2>Compression API Functions</h2>
+<h2>Filter and Compression API Functions</h2>
-This function enable the user to configure a new compression
-method for the local environment.
+These functions enable the user to configure new filters
+for the local environment.
-<table border=0>
+<table border=0 width=80%>
<tr><td valign=top>
<ul>
<li><a href="#Compression-Register">H5Zregister</a>
</ul>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
<ul>
- &nbsp;
+ <li><a href="#Compression-Unregister">H5Zunregister</a>
+</ul>
+</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
+<ul>
+ <li><a href="#Compression-FilterAvail">H5Zfilter_avail</a>
</ul>
</td></tr>
</table>
<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.
+HDF5 supports a filter pipeline that provides the capability for standard
+and customized raw data processing during I/O operations.
+HDF5 is distributed with a small set of standard filters such as
+compression (gzip and a shuffling algorithm) and
+error checking (Fletcher32 checksum).
+For further flexibility, the library includes tools enabling a
+user application to extend the pipeline through the
+creation and registration of customized filters.
+<p>
+As mentioned above, one set of filters distributed with HDF5 provides
+built-in methods for raw data compression.
+The flexibility of the filter pipeline implementation enables the
+definition of additional compression methods by a user application.
+A compression method<br>
+&nbsp;&mdash;&nbsp;
+ is associated with a dataset when the dataset is created,<br>
+&nbsp;&mdash;&nbsp;
+ can be used only with chunked data (ie., datasets stored in the
+ <code>H5D_CHUNKED</code> storage layout), and<br>
+&nbsp;&mdash;&nbsp;
+ is applied independently to each chunk of the dataset.
<p>
The HDF5 library does not support compression for contiguous datasets
because of the difficulty of implementing random access for partial I/O.
@@ -84,28 +104,42 @@ data compression.
<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>,
+ <dd><em>herr_t</em> <code>H5Zregister</code>(<em>H5Z_filter_t</em> <code>filter</code>,
+ <em>const char *</em><code>comment</code>,
<em>H5Z_func_t</em> <code>function</code>
)
<dt><strong>Purpose:</strong>
- <dd> Registers new compression / uncompression function.
+ <dd> Registers new filter.
<dt><strong>Description:</strong>
- <dd><code>H5Zregister</code> registers a new compression / uncompression
- function for the compression method specified by
- the method number, <code>method</code>.
+ <dd><code>H5Zregister</code> registers a new filter with the
+ HDF5 library.
+ <p>
+ Making a new filter available to an application is a two-step
+ process. The first step is to <span class="termEmphasis">define</span>
+ the new filter <code>function</code> as described below.
+ This step can be skipped only when the filter is predifined, as is
+ the case with the Fletcher32 checksum and shuffle filters that
+ are distributed with the HDF5 Library.
+ This call to <code>H5Zregister</code>,
+ <span class="termEmphasis">registering</span> the filter with the
+ library, is the second step.
+ <p>
+ The new filter is specified by the filter identifier
+ <code>filter</code>.
<p>
- <code>name</code> is used for debugging and may be the null pointer.
+ <code>comment</code> is used for debugging and may be
+ the null pointer.
<p>
- <code>function</code> is a user-defined function providing both
- compression and uncompression; it may be the null pointer.
+ <code>function</code> is a user-defined function
+ which performs the action of the filter.
<p>
- The statistics associated with a method number are not reset
+ The statistics associated with a filter are not reset
by this function; they accumulate over the life of the library.
- <p><strong>New filters</strong> are defined in two phases. Before a filter can be
- linked into the application with <code>H5Zregister</code>,
- <code>H5Z_func_t</code> must first be defined as follows:
+ <p><strong>New filters.</strong> Before a filter can be
+ linked into an application with <code>H5Zregister</code>,
+ the filter must be defined as described in the HDF5 Library
+ header file <code>H5Zpublic.h</code>:
<dir>
<em>typedef size_t</em> (*<code>H5Z_func_t</code>)
@@ -118,12 +152,12 @@ data compression.
</dir>
<p>The parameters <code>flags</code>, <code>cd_nelmts</code>,
- and <code>cd_values</code> are the same as for the
- <code>H5Pset_filter()</code> function.
+ and <code>cd_values</code> are the same as for the function
+ <code>H5Pset_filter</code>.
The additional flag <code>H5Z_FLAG_REVERSE</code> is set when
the filter is called as part of the input pipeline.
The parameter <code>*buf</code> points to the input buffer
- which has a total size of <code>*buf_size</code> bytes,
+ which has a size of <code>*buf_size</code> bytes,
<code>nbytes</code> of which are valid data.
<p>The filter should perform the transformation in place if
possible and return the number of valid bytes or zero for
@@ -136,13 +170,14 @@ data compression.
<dt><strong>Parameters:</strong>
<dl>
- <dt><em>H5Z_method_t</em> <code>method</code>
- <dd>IN: Number specifying compression method.
- <dt><em>const char *</em><code>name</code>
- <dd>IN: Name associated with the method number.
- Used for debugging purposes only.
+ <dt><em>H5Z_filter_t</em> <code>method</code>
+ <dd>IN: Filter identifier.
+ <dt><em>const char *</em><code>comment</code>
+ <dd>IN: String associated with the filter;
+ used for debugging purposes only.
+ May be the null pointer.
<dt><em>H5Z_func_t</em> <code>function</code>
- <dd>IN: Compression / uncompression method.
+ <dd>IN: Filter function.
</dl>
<dt><strong>Returns:</strong>
<dd>Returns a non-negative value if successful;
@@ -150,6 +185,75 @@ data compression.
</dl>
+
+
+<hr>
+<dl>
+ <dt><strong>Name:</strong> <a name="Compression-Unregister">H5Zunregister</a>
+ <dt><strong>Signature:</strong>
+ <dd><em>herr_t</em> <code>H5Zunregister</code>(<em>H5Z_filter_t</em> <code>filter</code>)
+ <dt><strong>Purpose:</strong>
+ <dd>Unregisters a filter.
+ <dt><strong>Description:</strong>
+ <dd><code>H5Zunregister</code> unregisters the filter
+ specified in <code>filter</code>.  
+ <p>
+ After a call to <code>H5Zunregister</code>, the filter
+ specified in <code>filter</code> will no longer be
+ available to the application.
+ <dt><strong>Parameters:</strong>
+ <dl>
+ <dt><em>H5Z_filter_t</em> <code>filter</code>
+ <dd>IN: Identifier of the filter to be unregistered.
+ </dl>
+ <dt><strong>Returns:</strong>
+ <dd>Returns a non-negative value if successful;
+ otherwise returns a negative value.
+ <!--
+ <dt><strong>Non-C API(s):</strong>
+ <dd><a href="fortran/h5p_FORTRAN.html#h5pget_nfilters_f"
+ target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
+ --> <!--
+ <img src="Graphics/Java.gif">
+ <img src="Graphics/C++.gif">
+ -->
+</dl>
+
+<hr>
+<dl>
+ <dt><strong>Name:</strong> <a name="Compression-FilterAvail">H5Zfilter_avail</a>
+ <dt><strong>Signature:</strong>
+ <dd><em>herr_t</em> <code>H5Zfilter_avail</code>(<em>H5Z_filter_t</em> <code>filter</code>)
+ <dt><strong>Purpose:</strong>
+ <dd>Determines whether a filter is available.
+ <dt><strong>Description:</strong>
+ <dd><code>H5Zfilter_avail</code> determines whether the filter
+ specified in <code>filter</code> is available to the application.
+ <dt><strong>Parameters:</strong>
+ <dl>
+ <dt><em>H5Z_filter_t</em> <code>filter</code>
+ <dd>IN: Filter identifier.
+ </dl>
+ <dt><strong>Returns:</strong>
+ <dd>Returns a non-negative value if successful;
+ otherwise returns a negative value.
+ <!--
+ <dt><strong>Non-C API(s):</strong>
+ <dd><a href="fortran/h5p_FORTRAN.html#h5pget_nfilters_f"
+ target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
+ --> <!--
+ <img src="Graphics/Java.gif">
+ <img src="Graphics/C++.gif">
+ -->
+</dl>
+
+
+
+
+
+
+
+
<!-- #BeginLibraryItem "/ed_libs/NavBar_RM.lbi" --><hr>
<center>
<table border=0 width=98%>
@@ -192,7 +296,7 @@ And in this document, the
Describes HDF5 Release 1.5, Unreleased Development Branch
</address><!-- #EndLibraryItem -->
-Last modified: 11 February 2003
+Last modified: 2 April 2003
</body>
</html>