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authorQuincey Koziol <koziol@hdfgroup.org>2003-07-03 20:45:53 (GMT)
committerQuincey Koziol <koziol@hdfgroup.org>2003-07-03 20:45:53 (GMT)
commit3523cd7413c4bfa1389ba32ea07782354b7f0456 (patch)
treedf8dd4ce6c658113c39f89dc7aa65d0f177a1daa /doc/html/H5.format.html
parent1a769534d88d8d257887aa299a4ab4856918fb92 (diff)
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[svn-r7161] Purpose:
Further updates Description: More updates on file format information. Platforms tested: Mozilla 1.4.0
Diffstat (limited to 'doc/html/H5.format.html')
-rw-r--r--doc/html/H5.format.html85
1 files changed, 51 insertions, 34 deletions
diff --git a/doc/html/H5.format.html b/doc/html/H5.format.html
index 418ba66..3cfb966 100644
--- a/doc/html/H5.format.html
+++ b/doc/html/H5.format.html
@@ -839,8 +839,8 @@
<td>Each tree has 2<em>K</em>+1 keys with 2<em>K</em>
child pointers interleaved between the keys. The number
of keys and child pointers actually containing valid
- values is determined by the <em>Entries Used</em> field. If
- that field is <em>N</em> then the B-link tree contains
+ values is determined by the node's <em>Entries Used</em> field.
+ If that field is <em>N</em> then the B-link tree contains
<em>N</em> child pointers and <em>N</em>+1 keys.</td>
</tr>
@@ -856,7 +856,22 @@
tree points.
<p>
The format of the key depends on the node type.
- For nodes of node type 1, the key is formatted as follows:
+ For nodes of node type 0 (group nodes), the key is formatted as
+ follows:
+ <center>
+ <table>
+ <tr valign=top align=left>
+ <td width=40%>A single field of <i>Size of Lengths</i>
+ bytes</td>
+ <td>Indicates the byte offset into the local heap
+ for the first object name in the subtree which
+ that key describes.</td>
+ </tr>
+ </table>
+ </center>
+ <p>
+ For nodes of node type 1 (chunked raw data nodes), the key is
+ formatted as follows:
<center>
<table>
<tr valign=top align=left>
@@ -867,46 +882,41 @@
<td>Filter mask, a 32-bit bitfield indicating which
filters have been applied to that chunk.</td>
</tr><tr valign=top align=left>
- <td><i>N</i> fields of 8 bytes each</td>
+ <td><em>N</em> 64-bit fields</td>
<td>A 64-bit index indicating the offset of the
chunk within the dataset where <i>N</i> is the number
of dimensions of the dataset. For example, if
a chunk in a 3-dimensional dataset begins at the
position <code>[5,5,5]</code>, there will be three
- such 8-bit indices, each with the value of
+ such 64-bit indices, each with the value of
<code>5</code>.</td>
</tr>
</table>
</center>
- <p>
- For nodes of node type 0, the key is formatted as follows:
- <center>
- <table>
- <tr valign=top align=left>
- <td width=40%>A single field of <i>Size of Lengths</i>
- bytes</td>
- <td>Indicates the byte offset into the local heap
- for the first object name in the subtree which
- that key describes.</td>
- </tr>
- </table>
- </center>
</td>
</tr>
<tr valign=top>
- <td>Child Pointers</td>
- <td>The tree node contains file addresses of subtrees or
+ <td>Child Pointer</td>
+ <td>
+ <P>The tree node contains file addresses of subtrees or
data depending on the node level. Nodes at Level 0 point
- to data addresses, either data chunk or group nodes.
+ to data addresses, either raw data chunk or group nodes.
Nodes at non-zero levels point to other nodes of the
- same B-tree.</td>
+ same B-tree.
+ </P>
+ <P>For raw data chunk nodes, the child pointer is the address
+ of a single raw data chunk. For group nodes, the child pointer
+ points to a <A href="#SymbolTable">symbol table</A>, which contains
+ information for multiple symbol table entries.
+ </P>
+ </td>
</tr>
</table>
</center>
<p>
- Each B-tree node looks like this:
+ Conceptually, each B-tree node looks like this:
<center>
<table>
@@ -929,7 +939,7 @@
above Level 0) or to data (at Level 0).
Each key[<i>i</i>] describes an <i>item</i> stored by the B-tree
(a chunk or an object of a group node). The range of values
- represented by child[<i>i</i>] are indicated by key[<i>i</i>]
+ represented by child[<i>i</i>] is indicated by key[<i>i</i>]
and key[<i>i</i>+1].
@@ -956,11 +966,12 @@
<h3><a name="SymbolTable">Disk Format: Level 1B - Group and Symbol Nodes</a></h3>
<p>A group is an object internal to the file that allows
- arbitrary nesting of objects (including other groups).
- A group maps a set of names to a set of file
- address relative to the base address. Certain meta data
- for an object to which the group points can be duplicated
- in the group symbol table in addition to the object header.
+ arbitrary nesting of objects within the file (including other groups).
+ A group maps a set of names in the group to a set of relative
+ file addresses where objects with those names are located in
+ the file. Certain metadata for an object to which the group points
+ can be cached in the group's symbol table in addition to the
+ object's header.
<p>An HDF5 object name space can be stored hierarchically by
partitioning the name into components and storing each
@@ -995,7 +1006,7 @@
<tr align=center>
<td>Version Number</td>
- <td>Reserved for Future Use</td>
+ <td>Reserved (0)</td>
<td colspan=2>Number of Symbols</td>
<tr align=center>
@@ -1013,7 +1024,7 @@
<tr valign=top>
<td>Node Signature</td>
- <td>The ASCII character string <code>SNOD</code> is
+ <td>The ASCII character string "<code>SNOD</code>" is
used to indicate the
beginning of a group node. This gives file
consistency checking utilities a better chance of
@@ -1023,7 +1034,8 @@
<tr valign=top>
<td>Version Number</td>
<td>The version number for the group node. This
- document describes version 1.</td>
+ document describes version 1. (There is no version '0'
+ of the group node)</td>
</tr>
<tr valign=top>
@@ -1038,8 +1050,13 @@
<tr valign=top>
<td>Group Entries</td>
- <td>Each symbol has an entry in the group node.
- The format of the entry is described below.</td>
+ <td>
+ <P>Each symbol has an entry in the group node.
+ The format of the entry is described below.
+ There are 2<EM>K</EM> entries in each group node, where
+ <EM>K</EM> is the "Group Leaf Node K" value from the
+ <A href="#SuperBlock">super block</A>.
+ </td>
</tr>
</table>
</center>