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authorFrank Baker <fbaker@hdfgroup.org>1999-05-03 21:54:10 (GMT)
committerFrank Baker <fbaker@hdfgroup.org>1999-05-03 21:54:10 (GMT)
commita3d84da7df8e3d4226eb937cbabd3384fabd2762 (patch)
tree8576203277e9ce7e64da91f858650917b326934b /doc/html
parent2ea07058c9fd49188d57b15699fbca05510b4da1 (diff)
downloadhdf5-a3d84da7df8e3d4226eb937cbabd3384fabd2762.zip
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[svn-r1244] Datatypes.html
DatatypesEnum.html EnumMap.gif Added enumeration datatypes -- First pass, only minimal editing. Intro paragraph in Datatypes.html; details in DatatypesEnum.html. EnumMap.gif is a figure for DatatypesEnum.html. Tools.html Added new h5toh4 supported object and data type. H5.intro.html Corrected transposed "start coordinates" in Example 1.
Diffstat (limited to 'doc/html')
-rw-r--r--doc/html/Datatypes.html21
-rw-r--r--doc/html/DatatypesEnum.html921
-rw-r--r--doc/html/EnumMap.gifbin0 -> 1682 bytes
-rw-r--r--doc/html/H5.intro.html2
-rw-r--r--doc/html/Tools.html16
5 files changed, 949 insertions, 11 deletions
diff --git a/doc/html/Datatypes.html b/doc/html/Datatypes.html
index 604b480..f0872b6 100644
--- a/doc/html/Datatypes.html
+++ b/doc/html/Datatypes.html
@@ -1150,7 +1150,21 @@ H5Tinsert (surf_id, "y", HOFFSET(surf_t,y), complex_id);
</table>
</center>
- <h2>7. Sharing Data Types among Datasets</h2>
+ <a name="Datatypes_Enum">&nbsp;</a>
+ <h2>7. <a href="DatatypesEnum.html">Enumeration Data Types</a></h2>
+
+ An HDF5 enumeration data type is a 1:1 mapping between a set of
+ symbols and a set of integer values, and an order is imposed on
+ the symbols by their integer values. The symbols are passed
+ between the application and library as character strings and all
+ the values for a particular enumeration type are of the same
+ integer type, which is not necessarily a native type.
+ <p>
+ Details of enumeration data types and the related functions
+ are discussed on a separate
+ <a href="DatatypesEnum.html">Enumeration Data Types</a> page.
+
+ <h2>8. Sharing Data Types among Datasets</h2>
<p>If a file has lots of datasets which have a common data type
then the file could be made smaller by having all the datasets
@@ -1196,7 +1210,7 @@ hid_t dset4 = H5Dcreate (file, "dset4", t2, space, H5P_DEFAULT);
</center>
<a name="Datatypes-DataConversion">
- <h2>8. Data Conversion</h2>
+ <h2>9. Data Conversion</h2>
</a>
<p>The library is capable of converting data from one type to
@@ -1553,7 +1567,6 @@ H5Tregister(H5T_PERS_SOFT, "cus2be",
conversion path whether that conversion path was actually used
or not.
-<<<<<<< Datatypes.html
<hr>
@@ -1621,7 +1634,7 @@ And in this document, the
</address>
<!-- Created: Thu Dec 4 14:57:32 EST 1997 -->
<!-- hhmts start -->
-Last modified: Wed Dec 16 13:04:58 EST 1998
+Last modified: 30 April 1999
<!-- hhmts end -->
diff --git a/doc/html/DatatypesEnum.html b/doc/html/DatatypesEnum.html
new file mode 100644
index 0000000..414ab2f
--- /dev/null
+++ b/doc/html/DatatypesEnum.html
@@ -0,0 +1,921 @@
+<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
+<html>
+ <head>
+ <title>Enumeration Data Types in the Data Type Interface (H5T)</title>
+ </head>
+
+ <body bgcolor="#FFFFFF">
+
+
+<hr>
+<center>
+<table border=0 width=98%>
+<tr><td valign=top align=left>
+ <a href="H5.intro.html">Introduction to HDF5</a>&nbsp;<br>
+ <a href="RM_H5Front.html">HDF5 Reference Manual</a>&nbsp;<br>
+ <a href="index.html">Other HDF5 documents and links</a>&nbsp;<br>
+ <!--
+ <a href="Glossary.html">Glossary</a><br>
+ -->
+</td>
+<td valign=top align=right>
+ And in this document, the
+ <a href="H5.user.html">HDF5 User's Guide</a>:&nbsp;&nbsp;&nbsp;&nbsp;
+ <a href="Files.html">Files</a>&nbsp;&nbsp;
+ <br>
+ <a href="Datasets.html">Datasets</a>&nbsp;&nbsp;
+ <a href="Datatypes.html">Data Types</a>&nbsp;&nbsp;
+ <a href="Dataspaces.html">Dataspaces</a>&nbsp;&nbsp;
+ <a href="Groups.html">Groups</a>&nbsp;&nbsp;
+ <a href="References.html">References</a>&nbsp;&nbsp;
+ <br>
+ <a href="Attributes.html">Attributes</a>&nbsp;&nbsp;
+ <a href="Properties.html">Property Lists</a>&nbsp;&nbsp;
+ <a href="Errors.html">Error Handling</a>&nbsp;&nbsp;
+ <a href="Filters.html">Filters</a>&nbsp;&nbsp;
+ <a href="Caching.html">Caching</a>&nbsp;&nbsp;
+ <br>
+ <a href="Chunking.html">Chunking</a>&nbsp;&nbsp;
+ <a href="Debugging.html">Debugging</a>&nbsp;&nbsp;
+ <a href="Environment.html">Environment</a>&nbsp;&nbsp;
+ <a href="ddl.html">DDL</a>&nbsp;&nbsp;
+ <a href="Ragged.html">Ragged Arrays</a>&nbsp;&nbsp;
+<!--
+<hr>
+And in this document, the
+<a href="H5.user.html">HDF5 User's Guide</a>:&nbsp;&nbsp;&nbsp;&nbsp;
+ <a href="Attributes.html">H5A</a>&nbsp;&nbsp;
+ <a href="Datasets.html">H5D</a>&nbsp;&nbsp;
+ <a href="Errors.html">H5E</a>&nbsp;&nbsp;
+ <a href="Files.html">H5F</a>&nbsp;&nbsp;
+ <a href="Groups.html">H5G</a>&nbsp;&nbsp;
+ <a href="Properties.html">H5P</a>&nbsp;&nbsp;
+ <a href="References.html">H5R & H5I</a>&nbsp;&nbsp;
+ <a href="Ragged.html">H5RA</a>&nbsp;&nbsp;
+ <a href="Dataspaces.html">H5S</a>&nbsp;&nbsp;
+ <a href="Datatypes.html">H5T</a>&nbsp;&nbsp;
+ <a href="Filters.html">H5Z</a>&nbsp;&nbsp;
+ <a href="Caching.html">Caching</a>&nbsp;&nbsp;
+ <a href="Chunking.html">Chunking</a>&nbsp;&nbsp;
+ <a href="Debugging.html">Debugging</a>&nbsp;&nbsp;
+ <a href="Environment.html">Environment</a>&nbsp;&nbsp;
+ <a href="ddl.html">DDL</a>&nbsp;&nbsp;
+-->
+</td></tr>
+</table>
+</center>
+<hr>
+
+
+ <h1>The Data Type Interface (H5T) <font size=-1><i>(contitnued)</i></font></h1>
+
+ <p align=right><font size=-1><i>
+ (Return to <a href="Datatypes.html#Datatypes_Enum">Data Types Interface (H5T)</a>.)
+ </font></i>
+
+ <h2>7. Enumeration Data Types</h2>
+
+ <h3>7.1. Introduction</h2>
+
+ <p>An HDF enumeration data type is a 1:1 mapping between a set of
+ symbols and a set of integer values, and an order is imposed on
+ the symbols by their integer values. The symbols are passed
+ between the application and library as character strings and all
+ the values for a particular enumeration type are of the same
+ integer type, which is not necessarily a native type.
+
+ <h3>7.2. Creation</h2>
+
+ <p>Creation of an enumeration data type resembles creation of a
+ compound data type: first an empty enumeration type is created,
+ then members are added to the type, then the type is optionally
+ locked.
+
+ <dl>
+ <dt><code>hid_t H5Tcreate(H5T_class_t <em>type_class</em>,
+ size_t <em>size</em>)</code>
+ <dd>This function creates a new empty enumeration data type based
+ on a native signed integer type. The first argument is the
+ constant <code>H5T_ENUM</code> and the second argument is the
+ size in bytes of the native integer on which the enumeration
+ type is based. If the architecture does not support a native
+ signed integer of the specified size then an error is
+ returned.
+
+ <pre>
+/* Based on a native signed short */
+hid_t hdf_en_colors = H5Tcreate(H5T_ENUM, sizeof(short));</pre>
+
+
+ <dt><code>hid_t H5Tenum_create(hid_t <em>base</em>)</code>
+ <dd>This function creates a new empty enumeration data type based
+ on some integer data type <em>base</em> and is a
+ generalization of the <code>H5Tcreate()</code> function. This
+ function is useful when creating an enumeration type based on
+ some non-native integer data type, but it can be used for
+ native types as well.
+
+ <pre>
+/* Based on a native unsigned short */
+hid_t hdf_en_colors_1 = H5Tenum_create(H5T_NATIVE_USHORT);
+
+/* Based on a MIPS 16-bit unsigned integer */
+hid_t hdf_en_colors_2 = H5Tenum_create(H5T_MIPS_UINT16);
+
+/* Based on a big-endian 16-bit unsigned integer */
+hid_t hdf_en_colors_3 = H5Tenum_create(H5T_STD_U16BE);</pre>
+
+
+ <dt><code>herr_t H5Tenum_insert(hid_t <em>etype</em>, const char
+ *<em>symbol</em>, void *<em>value</em>)</code>
+ <dd>Members are inserted into the enumeration data type
+ <em>etype</em> with this function. Each member has a symbolic
+ name <em>symbol</em> and some integer representation
+ <em>value</em>. The <em>value</em> argument must point to a value
+ of the same data type as specified when the enumeration type
+ was created. The order of member insertion is not important
+ but all symbol names and values must be unique within a
+ particular enumeration type.
+
+ <pre>
+short val;
+H5Tenum_insert(hdf_en_colors, "RED", (val=0,&amp;val));
+H5Tenum_insert(hdf_en_colors, "GREEN", (val=1,&amp;val));
+H5Tenum_insert(hdf_en_colors, "BLUE", (val=2,&amp;val));
+H5Tenum_insert(hdf_en_colors, "WHITE", (val=3,&amp;val));
+H5Tenum_insert(hdf_en_colors, "BLACK", (val=4,&amp;val));</pre>
+
+
+ <dt><code>herr_t H5Tlock(hid_t <em>etype</em>)</code>
+ <dd>This function locks a data type so it cannot be modified or
+ freed unless the entire HDF5 library is closed. Its use is
+ completely optional but using it on an application data type
+ makes that data type act like a predefined data type.
+
+ <pre>
+H5Tlock(hdf_en_colors);</pre>
+
+ </dl>
+
+ <h3>7.3. Integer Operations</h2>
+
+ <p>Because an enumeration data type is derived from an integer
+ data type, any operation which can be performed on integer data
+ types can also be performed on enumeration data types. This
+ includes:
+
+ <p>
+ <center>
+ <table>
+ <tr>
+ <td><code>H5Topen()</code></td>
+ <td><code>H5Tcreate()</code></td>
+ <td><code>H5Tcopy()</code></td>
+ <td><code>H5Tclose()</code></td>
+ </tr><tr>
+ <td><code>H5Tequal()</code></td>
+ <td><code>H5Tlock()</code></td>
+ <td><code>H5Tcommit()</code></td>
+ <td><code>H5Tcommitted()</code></td>
+ </tr><tr>
+ <td><code>H5Tget_class()</code></td>
+ <td><code>H5Tget_size()</code></td>
+ <td><code>H5Tget_order()</code></td>
+ <td><code>H5Tget_pad()</code></td>
+ </tr><tr>
+ <td><code>H5Tget_precision()</code></td>
+ <td><code>H5Tget_offset()</code></td>
+ <td><code>H5Tget_sign()</code></td>
+ <td><code>H5Tset_size()</code></td>
+ </tr><tr>
+ <td><code>H5Tset_order()</code></td>
+ <td><code>H5Tset_precision()</code></td>
+ <td><code>H5Tset_offset()</code></td>
+ <td><code>H5Tset_pad()</code></td>
+ </tr><tr>
+ <td><code>H5Tset_sign()</code></td>
+ </tr>
+ </table>
+ </center>
+
+ <p>In addition, the new function <code>H5Tget_super()</code> will
+ be defined for all data types that are derived from existing
+ types (currently just enumeration types).
+
+ <dl>
+ <dt><code>hid_t H5Tget_super(hid_t <em>type</em>)</code>
+ <dd>Return the data type from which <em>type</em> is
+ derived. When <em>type</em> is an enumeration data type then
+ the returned value will be an integer data type but not
+ necessarily a native type. One use of this function would be
+ to create a new enumeration type based on the same underlying
+ integer type and values but with possibly different symbols.
+
+ <pre>
+hid_t itype = H5Tget_super(hdf_en_colors);
+hid_t hdf_fr_colors = H5Tenum_create(itype);
+H5Tclose(itype);
+
+short val;
+H5Tenum_insert(hdf_fr_colors, "ouge", (val=0,&amp;val));
+H5Tenum_insert(hdf_fr_colors, "vert", (val=1,&amp;val));
+H5Tenum_insert(hdf_fr_colors, "bleu", (val=2,&amp;val));
+H5Tenum_insert(hdf_fr_colors, "blanc", (val=3,&amp;val));
+H5Tenum_insert(hdf_fr_colors, "noir", (val=4,&amp;val));
+H5Tlock(hdf_fr_colors);</pre>
+ </dl>
+
+ <h3>7.4. Type Functions</h2>
+
+ <p>A small set of functions is available for querying properties
+ of an enumeration type. These functions are likely to be used
+ by browsers to display data type information.
+
+ <dl>
+ <dt><code>int H5Tget_nmembers(hid_t <em>etype</em>)</code>
+ <dd>When given an enumeration data type <em>etype</em> this
+ function returns the number of members defined for that
+ type. This function is already implemented for compound data
+ types.
+
+ <br><br>
+ <dt><code>char *H5Tget_member_name(hid_t <em>etype</em>, int
+ <em>membno</em>)</code>
+ <dd>Given an enumeration data type <em>etype</em> this function
+ returns the symbol name for the member indexed by
+ <em>membno</em>. Members are numbered from zero to
+ <em>N</em>-1 where <em>N</em> is the return value from
+ <code>H5Tget_nmembers()</code>. The members are stored in no
+ particular order. This function is already implemented for
+ compound data types. If an error occurs then the null pointer
+ is returned. The return value should be freed by calling
+ <code>free()</code>.
+
+ <br><br>
+ <dt><code>herr_t H5Tget_member_value(hid_t <em>etype</em>, int
+ <em>membno</em>, void *<em>value</em>/*out*/)</code>
+ <dd>Given an enumeration data type <em>etype</em> this function
+ returns the value associated with the member indexed by
+ <em>membno</em> (as described for
+ <code>H5Tget_member_name()</code>). The value returned
+ is in the domain of the underlying integer
+ data type which is often a native integer type. The
+ application should ensure that the memory pointed to by
+ <em>value</em> is large enough to contain the result (the size
+ can be obtained by calling <code>H5Tget_size()</code> on
+ either the enumeration type or the underlying integer type
+ when the type is not known by the C compiler.
+
+ <pre>
+int i, n = H5Tget_nmembers(hdf_en_colors);
+for (i=0; i&lt;n; i++) {
+ char *symbol = H5Tget_member_name(hdf_en_colors, i);
+ short val;
+ H5Tget_member_value(hdf_en_colors, i, &amp;val);
+ printf("#%d %20s = %d\n", i, symbol, val);
+ free(symbol);
+}</pre>
+
+ <p>
+ Output:
+ <pre>
+#0 BLACK = 4
+#1 BLUE = 2
+#2 GREEN = 1
+#3 RED = 0
+#4 WHITE = 3</pre>
+ </dl>
+
+ <h3>7.5. Data Functions</h2>
+
+ <p>In addition to querying about the enumeration type properties,
+ an application may want to make queries about enumerated
+ data. These functions perform efficient mappings between symbol
+ names and values.
+
+ <dl>
+ <dt><code>herr_t H5Tenum_valueof(hid_t <em>etype</em>, const char
+ *<em>symbol</em>, void *<em>value</em>/*out*/)</code>
+ <dd>Given an enumeration data type <em>etype</em> this function
+ returns through <em>value</em> the bit pattern associated with
+ the symbol name <em>symbol</em>. The <em>value</em> argument
+ should point to memory which is large enough to hold the result,
+ which is returned as the underlying integer data type specified
+ when the enumeration type was created, often a native integer
+ type.
+
+ <br><br>
+ <dt><code>herr_t H5Tenum_nameof(hid_t <em>etype</em>, void
+ *<em>value</em>, char *<em>symbol</em>, size_t
+ <em>size</em>)</code>
+ <dd>This function translates a bit pattern pointed to by
+ <em>value</em> to a symbol name according to the mapping
+ defined in the enumeration data type <em>etype</em> and stores
+ at most <em>size</em> characters of that name (counting the
+ null terminator) to the <em>symbol</em> buffer. If the name is
+ longer than the result buffer then the result is not null
+ terminated and the function returns failure. If <em>value</em>
+ points to a bit pattern which is not in the domain of the
+ enumeration type then the first byte of the <em>symbol</em>
+ buffer is set to zero and the function fails.
+
+ <pre>
+short data[1000] = {4, 2, 0, 0, 5, 1, ...};
+int i;
+char symbol[32];
+
+for (i=0; i<1000; i++) {
+ if (H5Tenum_nameof(hdf_en_colors, data+i, symbol,
+ sizeof symbol))&lt;0) {
+ if (symbol[0]) {
+ strcpy(symbol+sizeof(symbol)-4, "...");
+ } else {
+ strcpy(symbol, "UNKNOWN");
+ }
+ }
+ printf("%d %s\n", data[i], symbol);
+}
+printf("}\n");</pre>
+
+ <p>
+ Output:
+ <pre>
+
+4 BLACK
+2 BLUE
+0 RED
+0 RED
+5 UNKNOWN
+1 GREEN
+...</pre>
+ </dl>
+
+ <h3>7.6. Conversion</h2>
+
+ <p>Enumerated data can be converted from one type to another
+ provided the destination enumeration type contains all the
+ symbols of the source enumeration type. The conversion operates
+ by matching up the symbol names of the source and destination
+ enumeration types to build a mapping from source value to
+ destination value. For instance, if we are translating from an
+ enumeration type that defines a sequence of integers as the
+ values for the colors to a type that defines a different bit for
+ each color then the mapping might look like this:
+
+ <p><img src="EnumMap.gif" alt="Enumeration Mapping">
+
+ <p>That is, a source value of <code>2</code> which corresponds to
+ <code>BLUE</code> would be mapped to <code>0x0004</code>. The
+ following code snippet builds the second data type, then
+ converts a raw data array from one data type to another, and
+ then prints the result.
+
+ <pre>
+/* Create a new enumeration type */
+short val;
+hid_t bits = H5Tcreate(H5T_ENUM, sizeof val);
+H5Tenum_insert(bits, "RED", (val=0x0001,&amp;val));
+H5Tenum_insert(bits, "GREEN", (val=0x0002,&amp;val));
+H5Tenum_insert(bits, "BLUE", (val=0x0004,&amp;val));
+H5Tenum_insert(bits, "WHITE", (val=0x0008,&amp;val));
+H5Tenum_insert(bits, "BLACK", (val=0x0010,&amp;val));
+
+/* The data */
+short data[6] = {1, 4, 2, 0, 3, 5};
+
+/* Convert the data from one type to another */
+H5Tconvert(hdf_en_colors, bits, 5, data, NULL);
+
+/* Print the data */
+for (i=0; i&lt;6; i++) {
+ printf("0x%04x\n", (unsigned)(data[i]));
+}</pre>
+
+ <p>
+ Output:
+ <pre>
+
+0x0002
+0x0010
+0x0004
+0x0001
+0x0008
+0xffff</pre>
+
+ <p>If the source data stream contains values which are not in the
+ domain of the conversion map then an overflow exception is
+ raised within the library, causing the application defined
+ overflow handler to be invoked (see
+ <code>H5Tset_overflow()</code>). If no overflow handler is
+ defined then all bits of the destination value will be set.
+
+ <p>The HDF library will not provide conversions between enumerated
+ data and integers although the application is free to do so
+ (this is a policy we apply to all classes of HDF data
+ types). However, since enumeration types are derived from
+ integer types it is permissible to treat enumerated data as
+ integers and perform integer conversions in that context.
+
+ <h3>7.7. Symbol Order</h2>
+
+ <p>Symbol order is determined by the integer values associated
+ with each symbol. When the integer data type is a native type,
+ testing the relative order of two symbols is an easy process:
+ simply compare the values of the symbols. If only the symbol
+ names are available then the values must first be determined by
+ calling <code>H5Tenum_valueof()</code>.
+
+ <pre>
+short val1, val2;
+H5Tenum_valueof(hdf_en_colors, "WHITE", &amp;val1);
+H5Tenum_valueof(hdf_en_colors, "BLACK", &amp;val2);
+if (val1 &lt; val2) ...</pre>
+
+ <p>When the underlying integer data type is not a native type then
+ the easiest way to compare symbols is to first create a similar
+ enumeration type that contains all the same symbols but has a
+ native integer type (HDF type conversion features can be used to
+ convert the non-native values to native values). Once we have a
+ native type we can compare symbol order as just described. If
+ <code>foreign</code> is some non-native enumeration type then a
+ native type can be created as follows:
+
+ <pre>
+int n = H5Tget_nmembers(foreign);
+hid_t itype = H5Tget_super(foreign);
+void *val = malloc(n * MAX(H5Tget_size(itype), sizeof(int)));
+char *name = malloc(n * sizeof(char*));
+int i;
+
+/* Get foreign type information */
+for (i=0; i&lt;n; i++) {
+ name[i] = H5Tget_member_name(foreign, i);
+ H5Tget_member_value(foreign, i,
+ (char*)val+i*H5Tget_size(foreign));
+}
+
+/* Convert integer values to new type */
+H5Tconvert(itype, H5T_NATIVE_INT, n, val, NULL);
+
+/* Build a native type */
+hid_t native = H5Tenum_create(H5T_NATIVE_INT);
+for (i=0; i&lt;n; i++) {
+ H5Tenum_insert(native, name[i], ((int*)val)[i]);
+ free(name[i]);
+}
+free(name);
+free(val);</pre>
+
+ <p>It is also possible to convert enumerated data to a new type
+ that has a different order defined for the symbols. For
+ instance, we can define a new type, <code>reverse</code> that
+ defines the same five colors but in the reverse order.
+
+ <pre>
+short val;
+int i;
+char sym[8];
+short data[5] = {0, 1, 2, 3, 4};
+
+hid_t reverse = H5Tenum_create(H5T_NATIVE_SHORT);
+H5Tenum_insert(reverse, "BLACK", (val=0,&amp;val));
+H5Tenum_insert(reverse, "WHITE", (val=1,&amp;val));
+H5Tenum_insert(reverse, "BLUE", (val=2,&amp;val));
+H5Tenum_insert(reverse, "GREEN", (val=3,&amp;val));
+H5Tenum_insert(reverse, "RED", (val=4,&amp;val));
+
+/* Print data */
+for (i=0; i<5; i++) {
+ H5Tenum_nameof(hdf_en_colors, data+i, sym, sizeof sym);
+ printf ("%d %s\n", data[i], sym);
+}
+
+puts("Converting...");
+H5Tconvert(hdf_en_colors, reverse, 5, data, NULL);
+
+/* Print data */
+for (i=0; i<5; i++) {
+ H5Tenum_nameof(reverse, data+i, sym, sizeof sym);
+ printf ("%d %s\n", data[i], sym);
+}</pre>
+
+ <p>
+ Output:
+ <pre>
+0 RED
+1 GREEN
+2 BLUE
+3 WHITE
+4 BLACK
+Converting...
+4 RED
+3 GREEN
+2 BLUE
+1 WHITE
+0 BLACK</pre>
+
+ <h3>7.8. Equality</h2>
+
+ <p>The order that members are inserted into an enumeration type is
+ unimportant; the important part is the associations between the
+ symbol names and the values. Thus, two enumeration data types
+ will be considered equal if and only if both types have the same
+ symbol/value associations and both have equal underlying integer
+ data types. Type equality is tested with the
+ <code>H5Tequal()</code> function.
+
+ <h3>7.9. Interacting with C's <code>enum</code> Type</h2>
+
+ <p>Although HDF enumeration data types are similar to C
+ <code>enum</code> data types, there are some important
+ differences:
+
+ <p>
+ <center>
+ <table border width="80%">
+ <tr>
+ <th>Difference</th>
+ <th>Motivation/Implications</th>
+ </tr>
+
+ <tr>
+ <td valign=top>Symbols are unquoted in C but quoted in
+ HDF.</td>
+ <td valign=top>This allows the application to manipulate
+ symbol names in ways that are not possible with C.</td>
+ </tr>
+
+ <tr>
+ <td valign=top>The C compiler automatically replaces all
+ symbols with their integer values but HDF requires
+ explicit calls to do the same.</td>
+ <td valign=top>C resolves symbols at compile time while
+ HDF resolves symbols at run time.</td>
+ </tr>
+
+ <tr>
+ <td valign=top>The mapping from symbols to integers is
+ <em>N</em>:1 in C but 1:1 in HDF.</td>
+ <td valign=top>HDF can translate from value to name
+ uniquely and large <code>switch</code> statements are
+ not necessary to print values in human-readable
+ format.</td>
+ </tr>
+
+ <tr>
+ <td valign=top>A symbol must appear in only one C
+ <code>enum</code> type but may appear in multiple HDF
+ enumeration types.</td>
+ <td valign=top>The translation from symbol to value in HDF
+ requires the data type to be specified while in C the
+ data type is not necessary because it can be inferred
+ from the symbol.</td>
+ </tr>
+
+ <tr>
+ <td valign=top>The underlying integer value is always a
+ native integer in C but can be a foreign integer type in
+ HDF.</td>
+ <td valign=top>This allows HDF to describe data that might
+ reside on a foreign architecture, such as data stored in
+ a file.</td>
+ </tr>
+
+ <tr>
+ <td valign=top>The sign and size of the underlying integer
+ data type is chosen automatically by the C compiler but
+ must be fully specified with HDF.</td>
+ <td valign=top>Since HDF doesn't require finalization of a
+ data type, complete specification of the type must be
+ supplied before the type is used. Requiring that
+ information at the time of type creation was a design
+ decision to simplify the library.</td>
+ </tr>
+ </table>
+ </center>
+
+ <p>The examples below use the following C data types:
+
+ <p>
+ <table width="90%" bgcolor="white">
+ <tr>
+ <td>
+ <code><pre>
+/* English color names */
+typedef enum {
+ RED,
+ GREEN,
+ BLUE,
+ WHITE,
+ BLACK
+} c_en_colors;
+
+/* Spanish color names, reverse order */
+typedef enum {
+ NEGRO
+ BLANCO,
+ AZUL,
+ VERDE,
+ ROJO,
+} c_sp_colors;
+
+/* No enum definition for French names */
+ </pre></code>
+ </td>
+ </tr>
+ </table>
+
+ <h4>Creating HDF Types from C Types</h3>
+
+ <p>An HDF enumeration data type can be created from a C
+ <code>enum</code> type simply by passing pointers to the C
+ <code>enum</code> values to <code>H5Tenum_insert()</code>. For
+ instance, to create HDF types for the <code>c_en_colors</code>
+ type shown above:
+
+ <p>
+ <table width="90%" bgcolor="white">
+ <tr>
+ <td>
+ <code><pre>
+
+c_en_colors val;
+hid_t hdf_en_colors = H5Tcreate(H5T_ENUM, sizeof(c_en_colors));
+H5Tenum_insert(hdf_en_colors, "RED", (val=RED, &amp;val));
+H5Tenum_insert(hdf_en_colors, "GREEN", (val=GREEN,&amp;val));
+H5Tenum_insert(hdf_en_colors, "BLUE", (val=BLUE, &amp;val));
+H5Tenum_insert(hdf_en_colors, "WHITE", (val=WHITE,&amp;val));
+H5Tenum_insert(hdf_en_colors, "BLACK", (val=BLACK,&amp;val));</pre></code>
+ </td>
+ </tr>
+ </table>
+
+ <h4>Name Changes between Applications</h3>
+
+ <p>Occassionally two applicatons wish to exchange data but they
+ use different names for the constants they exchange. For
+ instance, an English and a Spanish program may want to
+ communicate color names although they use different symbols in
+ the C <code>enum</code> definitions. The communication is still
+ possible although the applications must agree on common terms
+ for the colors. The following example shows the Spanish code to
+ read the values assuming that the applications have agreed that
+ the color information will be exchanged using Enlish color
+ names:
+
+ <p>
+ <table width="90%" bgcolor="white">
+ <tr>
+ <td>
+ <code><pre>
+
+c_sp_colors val, data[1000];
+hid_t hdf_sp_colors = H5Tcreate(H5T_ENUM, sizeof(c_sp_colors));
+H5Tenum_insert(hdf_sp_colors, "RED", (val=ROJO, &amp;val));
+H5Tenum_insert(hdf_sp_colors, "GREEN", (val=VERDE, &amp;val));
+H5Tenum_insert(hdf_sp_colors, "BLUE", (val=AZUL, &amp;val));
+H5Tenum_insert(hdf_sp_colors, "WHITE", (val=BLANCO, &amp;val));
+H5Tenum_insert(hdf_sp_colors, "BLACK", (val=NEGRO, &amp;val));
+
+H5Dread(dataset, hdf_sp_colors, H5S_ALL, H5S_ALL, H5P_DEFAULT, data);</pre></code>
+ </td>
+ </tr>
+ </table>
+
+
+ <h4>Symbol Ordering across Applications</h3>
+
+ <p>Since symbol ordering is completely determined by the integer values
+ assigned to each symbol in the <code>enum</code> definition,
+ ordering of <code>enum</code> symbols cannot be preserved across
+ files like with HDF enumeration types. HDF can convert from one
+ application's integer values to the other's so a symbol in one
+ application's C <code>enum</code> gets mapped to the same symbol
+ in the other application's C <code>enum</code>, but the relative
+ order of the symbols is not preserved.
+
+ <p>For example, an application may be defined to use the
+ definition of <code>c_en_colors</code> defined above where
+ <code>WHITE</code> is less than <code>BLACK</code>, but some
+ other application might define the colors in some other
+ order. If each application defines an HDF enumeration type based
+ on that application's C <code>enum</code> type then HDF will
+ modify the integer values as data is communicated from one
+ application to the other so that a <code>RED</code> value
+ in the first application is also a <code>RED</code> value in the
+ other application.
+
+ <p>A case of this reordering of symbol names was also shown in the
+ previous code snippet (as well as a change of language), where
+ HDF changed the integer values so 0 (<code>RED</code>) in the
+ input file became 4 (<code>ROJO</code>) in the <code>data</code>
+ array. In the input file, <code>WHITE</code> was less than
+ <code>BLACK</code>; in the application the opposite is true.
+
+ <p>In fact, the ability to change the order of symbols is often
+ convenient when the enumeration type is used only to group
+ related symbols that don't have any well defined order
+ relationship.
+
+ <h4>Internationalization</h3>
+
+ <p>The HDF enumeration type conversion features can also be used
+ to provide internationalization of debugging output. A program
+ written with the <code>c_en_colors</code> data type could define
+ a separate HDF data type for languages such as English, Spanish,
+ and French and cast the enumerated value to one of these HDF
+ types to print the result.
+
+ <p>
+ <table width="90%" bgcolor="white">
+ <tr>
+ <td>
+ <code><pre>
+
+c_en_colors val, *data=...;
+
+hid_t hdf_sp_colors = H5Tcreate(H5T_ENUM, sizeof val);
+H5Tenum_insert(hdf_sp_colors, "ROJO", (val=RED, &amp;val));
+H5Tenum_insert(hdf_sp_colors, "VERDE", (val=GREEN, &amp;val));
+H5Tenum_insert(hdf_sp_colors, "AZUL", (val=BLUE, &amp;val));
+H5Tenum_insert(hdf_sp_colors, "BLANCO", (val=WHITE, &amp;val));
+H5Tenum_insert(hdf_sp_colors, "NEGRO", (val=BLACK, &amp;val));
+
+hid_t hdf_fr_colors = H5Tcreate(H5T_ENUM, sizeof val);
+H5Tenum_insert(hdf_fr_colors, "OUGE", (val=RED, &amp;val));
+H5Tenum_insert(hdf_fr_colors, "VERT", (val=GREEN, &amp;val));
+H5Tenum_insert(hdf_fr_colors, "BLEU", (val=BLUE, &amp;val));
+H5Tenum_insert(hdf_fr_colors, "BLANC", (val=WHITE, &amp;val));
+H5Tenum_insert(hdf_fr_colors, "NOIR", (val=BLACK, &amp;val));
+
+void
+nameof(lang_t language, c_en_colors val, char *name, size_t size)
+{
+ switch (language) {
+ case ENGLISH:
+ H5Tenum_nameof(hdf_en_colors, &amp;val, name, size);
+ break;
+ case SPANISH:
+ H5Tenum_nameof(hdf_sp_colors, &amp;val, name, size);
+ break;
+ case FRENCH:
+ H5Tenum_nameof(hdf_fr_colors, &amp;val, name, size);
+ break;
+ }
+}</pre></code>
+ </td>
+ </tr>
+ </table>
+
+ <h3>7.10. Goals That Have Been Met</h2>
+
+ <p>The main goal of enumeration types is to provide communication
+ of enumerated data using symbolic equivalence. That is, a
+ symbol written to a dataset by one application should be read as
+ the same symbol by some other application.
+
+ <p>
+ <table width="90%">
+ <tr>
+ <td valign=top><b>Architecture Independence</b></td>
+ <td valign=top>Two applications shall be able to exchange
+ enumerated data even when the underlying integer values
+ have different storage formats. HDF accomplishes this for
+ enumeration types by building them upon integer types.</td>
+ </tr>
+
+ <tr>
+ <td valign=top><b>Preservation of Order Relationship</b></td>
+ <td valign=top>The relative order of symbols shall be
+ preserved between two applications that use equivalent
+ enumeration data types. Unlike numeric values that have
+ an implicit ordering, enumerated data has an explicit
+ order defined by the enumeration data type and HDF
+ records this order in the file.</td>
+ </tr>
+
+ <tr>
+ <td valign=top><b>Order Independence</b></td>
+ <td valign=top>An application shall be able to change the
+ relative ordering of the symbols in an enumeration data
+ type. This is accomplished by defining a new type with
+ different integer values and converting data from one type
+ to the other.</td>
+ </tr>
+
+ <tr>
+ <td valign=top><b>Subsets</b></td>
+ <td valign=top>An application shall be able to read
+ enumerated data from an archived dataset even after the
+ application has defined additional members for the
+ enumeration type. An application shall be able to write
+ to a dataset when the dataset contains a superset of the
+ members defined by the application. Similar rules apply
+ for in-core conversions between enumerated data
+ types.</td>
+ </tr>
+
+ <tr>
+ <td valign=top><b>Targetable</b></td>
+ <td valign=top>An application shall be able to target a
+ particular architecture or application when storing
+ enumerated data. This is accomplished by allowing
+ non-native underlying integer types and converting the
+ native data to non-native data.</td>
+ </tr>
+
+ <tr>
+ <td valign=top><b>Efficient Data Transfer</b></td>
+ <td valign=top>An application that defines a file dataset
+ that corresponds to some native C enumerated data array
+ shall be able to read and write to that dataset directly
+ using only Posix read and write functions. HDF already
+ optimizes this case for integers, so the same optimization
+ will apply to enumerated data.
+ </tr>
+
+ <tr>
+ <td valign=top><b>Efficient Storage</b></td>
+ <td valign=top>Enumerated data shall be stored in a manner
+ which is space efficient. HDF stores the enumerated data
+ as integers and allows the application to chose the size
+ and format of those integers.</td>
+ </tr>
+ </table>
+
+
+ <p align=right><font size=-1><i>
+ (Return to <a href="Datatypes.html#Datatypes_Enum">Data Types Interface (H5T)</a>.)
+ </font></i>
+
+<hr>
+<center>
+<table border=0 width=98%>
+<tr><td valign=top align=left>
+ <a href="H5.intro.html">Introduction to HDF5</a>&nbsp;<br>
+ <a href="RM_H5Front.html">HDF5 Reference Manual</a>&nbsp;<br>
+ <a href="index.html">Other HDF5 documents and links</a>&nbsp;<br>
+ <!--
+ <a href="Glossary.html">Glossary</a><br>
+ -->
+</td>
+<td valign=top align=right>
+ And in this document, the
+ <a href="H5.user.html">HDF5 User's Guide</a>:&nbsp;&nbsp;&nbsp;&nbsp;
+ <a href="Files.html">Files</a>&nbsp;&nbsp;
+ <br>
+ <a href="Datasets.html">Datasets</a>&nbsp;&nbsp;
+ Data Types&nbsp;&nbsp;
+ <a href="Dataspaces.html">Dataspaces</a>&nbsp;&nbsp;
+ <a href="Groups.html">Groups</a>&nbsp;&nbsp;
+ <a href="References.html">References</a>&nbsp;&nbsp;
+ <br>
+ <a href="Attributes.html">Attributes</a>&nbsp;&nbsp;
+ <a href="Properties.html">Property Lists</a>&nbsp;&nbsp;
+ <a href="Errors.html">Error Handling</a>&nbsp;&nbsp;
+ <a href="Filters.html">Filters</a>&nbsp;&nbsp;
+ <a href="Caching.html">Caching</a>&nbsp;&nbsp;
+ <br>
+ <a href="Chunking.html">Chunking</a>&nbsp;&nbsp;
+ <a href="Debugging.html">Debugging</a>&nbsp;&nbsp;
+ <a href="Environment.html">Environment</a>&nbsp;&nbsp;
+ <a href="ddl.html">DDL</a>&nbsp;&nbsp;
+ <a href="Ragged.html">Ragged Arrays</a>&nbsp;&nbsp;
+<!--
+<hr>
+And in this document, the
+<a href="H5.user.html">HDF5 User's Guide</a>:&nbsp;&nbsp;&nbsp;&nbsp;
+ <a href="Attributes.html">H5A</a>&nbsp;&nbsp;
+ <a href="Datasets.html">H5D</a>&nbsp;&nbsp;
+ <a href="Errors.html">H5E</a>&nbsp;&nbsp;
+ <a href="Files.html">H5F</a>&nbsp;&nbsp;
+ <a href="Groups.html">H5G</a>&nbsp;&nbsp;
+ <a href="Properties.html">H5P</a>&nbsp;&nbsp;
+ <a href="References.html">H5R & H5I</a>&nbsp;&nbsp;
+ <a href="Ragged.html">H5RA</a>&nbsp;&nbsp;
+ <a href="Dataspaces.html">H5S</a>&nbsp;&nbsp;
+ <a href="Datatypes.html">H5T</a>&nbsp;&nbsp;
+ <a href="Filters.html">H5Z</a>&nbsp;&nbsp;
+ <a href="Caching.html">Caching</a>&nbsp;&nbsp;
+ <a href="Chunking.html">Chunking</a>&nbsp;&nbsp;
+ <a href="Debugging.html">Debugging</a>&nbsp;&nbsp;
+ <a href="Environment.html">Environment</a>&nbsp;&nbsp;
+ <a href="ddl.html">DDL</a>&nbsp;&nbsp;
+-->
+</td></tr>
+</table>
+</center>
+
+
+<hr>
+<address>
+<a href="mailto:hdfhelp@ncsa.uiuc.edu">HDF Help Desk</a>
+</address>
+<!-- Created: Thu Dec 4 14:57:32 EST 1997 -->
+<!-- hhmts start -->
+Last modified: 30 April 1999
+<!-- hhmts end -->
+
+
+</body>
+</html>
diff --git a/doc/html/EnumMap.gif b/doc/html/EnumMap.gif
new file mode 100644
index 0000000..d06f06a
--- /dev/null
+++ b/doc/html/EnumMap.gif
Binary files differ
diff --git a/doc/html/H5.intro.html b/doc/html/H5.intro.html
index c3f7cb7..6c32ad7 100644
--- a/doc/html/H5.intro.html
+++ b/doc/html/H5.intro.html
@@ -696,7 +696,7 @@ the data is stored in another union of hyperslabs in the memory dataspace.
<FONT FACE="Times"><P>Four parameters are required to describe a completely general hyperslab. Each parameter is an array whose rank is the same as that of the dataspace:
<UL>
-</FONT><CODE><LI>start</CODE>: a starting location for the hyperslab. In the example <CODE>start</CODE> is (1,0).
+</FONT><CODE><LI>start</CODE>: a starting location for the hyperslab. In the example <CODE>start</CODE> is (0,1).
<CODE><LI>stride</CODE>: the number of elements to separate each element or block to be selected. In the example <CODE>stride</CODE><I> </I> is (4,3). If the stride parameter is set to NULL, the stride size defaults to 1 in each dimension.
<CODE><LI>count</CODE>: the number of elements or blocks to select along each dimension. In the example, <CODE>count</CODE> is (2,4).
<CODE><LI>block</CODE>: the size of the block selected from the dataspace. In the example, <CODE>block</CODE> is (3,2). If the block parameter is set to NULL, the block size defaults to a single element in each dimension, as if the block array was set to all 1s.</UL>
diff --git a/doc/html/Tools.html b/doc/html/Tools.html
index 33ab227..fbbf31d 100644
--- a/doc/html/Tools.html
+++ b/doc/html/Tools.html
@@ -326,10 +326,9 @@ These tools enable the user to examine HDF5 files interactively.
<p>
The <code>-h</code> option causes the following
syntax summary to be displayed:<br>
- <dir><code>
- h5toh4 file.h5 file.hdf<br>
- h5toh4 file.h5<br>
- h5toh4 -m file1.h5 file2.h5 ...<br></code></dir>
+ <pre> h5toh4 file.h5 file.hdf
+ h5toh4 file.h5
+ h5toh4 -m file1.h5 file2.h5 ...</pre>
<p>
@@ -358,6 +357,11 @@ These tools enable the user to examine HDF5 files interactively.
be fixed or extendable. The members of the
compound datatype are constrained to be no more
than rank 4.
+ <li>HDF5 dataset objects of single dimension and fixed length string
+ datatype are converted into HDF4 Vdata objects. The HDF4 Vdata is a
+ single field whose order is the length of the HDF5 string type. The
+ number of records of the Vdata is the length of the single dimension
+ which may be fixed or extendable.
</ul>
Other objects are not converted and are not recorded
@@ -365,7 +369,7 @@ These tools enable the user to examine HDF5 files interactively.
<p>
Attributes associated with any of the supported HDF5
objects are carried over to the HDF4 objects.
- Attributes may be of integer or floating point datatype
+ Attributes may be of integer, floating point, or fixed length string datatype
and they may have up to 32 fixed dimensions.
<p>
All datatypes are converted to big-endian.
@@ -432,7 +436,7 @@ Tools&nbsp;&nbsp;
<a href="mailto:hdfhelp@ncsa.uiuc.edu">HDF Help Desk</a>
<br>
-Last modified: 30 October 1998
+Last modified: 29 April 1999
</body>
</html>