diff options
| author | Elena Pourmal <epourmal@hdfgroup.org> | 1998-07-08 22:28:21 (GMT) |
|---|---|---|
| committer | Elena Pourmal <epourmal@hdfgroup.org> | 1998-07-08 22:28:21 (GMT) |
| commit | 49f626b81f028a09d5c287156120a5d405008335 (patch) | |
| tree | ee0178875371da97373cb5c08a2fa7a276f94ccd /doc/src/RM_H5T.html | |
| parent | 2f1f2ac4e44efef28ac7b7edaf4f9470b866c9fc (diff) | |
| download | hdf5-49f626b81f028a09d5c287156120a5d405008335.zip hdf5-49f626b81f028a09d5c287156120a5d405008335.tar.gz hdf5-49f626b81f028a09d5c287156120a5d405008335.tar.bz2 | |
[svn-r475] HDF5 Reference Manual files.
Main file is RM_H5Front.html. Created from the Alpha1 Ref. Manual, Alpha1
User's Guide Documents and the Alpha2 Source Code.
Diffstat (limited to 'doc/src/RM_H5T.html')
| -rw-r--r-- | doc/src/RM_H5T.html | 1323 |
1 files changed, 1323 insertions, 0 deletions
diff --git a/doc/src/RM_H5T.html b/doc/src/RM_H5T.html new file mode 100644 index 0000000..46fe6fc --- /dev/null +++ b/doc/src/RM_H5T.html @@ -0,0 +1,1323 @@ +<html> +<head><title> +HDF5/H5T Draft API Specification +</title></head> + +<body> + +<center> +<h1>H5T: Datatype Interface</h1> +</center> + +<h2>Datatype Object API Functions</h2> + +These functions create and manipulate the datatype which describes elements +of a dataset. + +<table border=0> +<tr><td valign=top> +<ul> + <li><a href="#Datatype-Create">H5Tcreate</a> + <li><a href="#Datatype-Copy">H5Tcopy</a> + <li><a href="#Datatype-Equal">H5Tequal</a> + <li><a href="#Datatype-Lock">H5Tlock</a> + <li><a href="#Datatype-GetClass">H5Tget_class</a> + <li><a href="#Datatype-GetSize">H5Tget_size</a> + <li><a href="#Datatype-SetSize">H5Tset_size</a> + <li><a href="#Datatype-GetOrder">H5Tget_order</a> + <li><a href="#Datatype-SetOrder">H5Tset_order</a> + <li><a href="#Datatype-GetPrecision">H5Tget_precision</a> + <li><a href="#Datatype-SetPrecision">H5Tset_precision</a> + <li><a href="#Datatype-GetOffset">H5Tget_offset</a> + <li><a href="#Datatype-SetOffset">H5Tset_offset</a> + <li><a href="#Datatype-GetPad">H5Tget_pad</a> +</ul> +</td><td> </td><td valign=top> +<ul> + <li><a href="#Datatype-SetPad">H5Tset_pad</a> + <li><a href="#Datatype-GetSign">H5Tget_sign</a> + <li><a href="#Datatype-SetSign">H5Tset_sign</a> + <li><a href="#Datatype-GetFields">H5Tget_fields</a> + <li><a href="#Datatype-SetFields">H5Tset_fields</a> + <li><a href="#Datatype-GetEbias">H5Tget_ebias</a> + <li><a href="#Datatype-SetEbias">H5Tset_ebias</a> + <li><a href="#Datatype-GetNorm">H5Tget_norm</a> + <li><a href="#Datatype-SetNorm">H5Tset_norm</a> + <li><a href="#Datatype-GetInpad">H5Tget_inpad</a> + <li><a href="#Datatype-SetInpad">H5Tset_inpad</a> + <li><a href="#Datatype-GetCset">H5Tget_cset</a> + <li><a href="#Datatype-SetCset">H5Tset_cset</a> + <li><a href="#Datatype-GetStrpad">H5Tget_strpad</a> +</ul> +</td><td> </td><td valign=top> +<ul> + <li><a href="#Datatype-SetStrpad">H5Tset_strpad</a> + <li><a href="#Datatype-GetNmembers">H5Tget_nmembers</a> + <li><a href="#Datatype-GetMemberName">H5Tget_member_name</a> + <li><a href="#Datatype-GetMemberOffset">H5Tget_member_offset</a> + <li><a href="#Datatype-GetMemberDims">H5Tget_member_dims</a> + <li><a href="#Datatype-GetMemberType">H5Tget_member_type</a> + <li><a href="#Datatype-Insert">H5Tinsert</a> + <li><a href="#Datatype-Pack">H5Tpack</a> + <li><a href="#Datatype-RegisterHard">H5Tregister_hard</a> + <li><a href="#Datatype-RegisterSoft">H5Tregister_soft</a> + <li><a href="#Datatype-Unregister">H5Tunregister</a> + <li><a href="#Datatype-Close">H5Tclose</a> +</ul> +</td></tr> +</table> + +<hr> + +<dl> +<dt><strong>Name:</strong> <a name="Datatype-Create">H5Tcreate</a> +<dt><strong>Signature:</strong> + <dd><em>hid_t </em><code>H5Tcreate</code>(<em>H5T_class_t </em><code>class</code>, + <em>size_t</em><code>size</code> + ) +<dt><strong>Description:</strong> + <dd>This function creates a new dataype of the specified class with the + specified number of bytes. Currently, only the <code>H5T_COMPOUND</code> + datatype class is supported with this function, use <code>H5Tcopy</code> + to create integer or floating-point datatypes. The datatype ID + returned from this function should be released with H5Tclose or resource + leaks will result. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>H5T_class_t</em> <code>class</code> + <dd>Class of datatype to create. + <dt><em>size_t</em> <code>size</code> + <dd>The number of bytes in the datatype to create. + </dl> +<dt><strong>Returns:</strong> + <dd>Datatype ID on success, negative on failure. +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-Copy">H5Tcopy</a> +<dt><strong>Signature:</strong> + <dd><em>hid_t </em><code>H5Tcopy</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function copies an existing datatype. The datatype ID returned + should be released with H5Tclose or resource leaks will occur. Native + datatypes supported by the library are: + <ul> <dl> + <dt>H5T_NATIVE_CHAR + <dd> Native character type, declare dataset array as 'char' + <dt>H5T_NATIVE_UCHAR + <dd> Native unsigned character type, declare dataset array as 'unsigned char' + <dt>H5T_NATIVE_SHORT + <dd> Native short type, declare dataset array as 'short' + <dt>H5T_NATIVE_USHORT + <dd> Native unsigned short type, declare dataset array as 'unsigned short' + <dt>H5T_NATIVE_INT + <dd> Native int type, declare dataset array as 'int' + <dt>H5T_NATIVE_UINT + <dd> Native unsigned int type, declare dataset array as 'unsigned int' + <dt>H5T_NATIVE_LONG + <dd> Native long type, declare dataset array as 'unsigned long' + <dt>H5T_NATIVE_ULONG + <dd> Native unsigned long type, declare dataset array as 'unsigned long' + <dt>H5T_NATIVE_LLONG + <dd> Native long long type, declare dataset array as 'unsigned long long' + <dt>H5T_NATIVE_ULLONG + <dd> Native unsigned long long type, declare dataset array as 'unsigned long long' + <dt>H5T_NATIVE_INT8 + <dd> Native signed 8-bit type, declare dataset array as 'int8' + <dt>H5T_NATIVE_UINT8 + <dd> Native unsigned 8-bit type, declare dataset array as 'uint8' + <dt>H5T_NATIVE_INT16 + <dd> Native signed 16-bit type, declare dataset array as 'int16' + <dt>H5T_NATIVE_UINT16 + <dd> Native unsigned 16-bit type, declare dataset array as 'uint16' + <dt>H5T_NATIVE_INT32 + <dd> Native signed 32-bit type, declare dataset array as 'int32' + <dt>H5T_NATIVE_UINT32 + <dd> Native unsigned 32-bit type, declare dataset array as 'uint32' + <dt>H5T_NATIVE_INT64 + <dd> Native signed 64-bit type, declare dataset array as 'uint64' + <dt>H5T_NATIVE_UINT64 + <dd> Native unsigned 64-bit type, declare dataset array as 'uint64' + <dt>H5T_NATIVE_FLOAT + <dd> Native single-precision float type, declare dataset array as 'float' + <dt>H5T_NATIVE_DOUBLE + <dd> Native double-precision float type, declare dataset array as 'double' + </dl> </ul> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to copy. + </dl> +<dt><strong>Returns:</strong> + <dd>Datatype ID on success, negative on failure. +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-Equal">H5Tequal</a> +<dt><strong>Signature:</strong> + <dd><em>hbool_t </em><code>H5Tequal</code>(<em>hid_t </em><code>type_id1</code>, + <em>hid_t</em><code>type_id2</code> + ) +<dt><strong>Description:</strong> + <dd>This function determines if two datatype IDs refer to the same + datatype. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id1</code> + <dd>ID of datatype to compare. + <dt><em>hid_t</em> <code>type_id2</code> + <dd>ID of datatype to compare. + </dl> +<dt><strong>Returns:</strong> + <dd>TRUE/FALSE/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-Lock">H5Tlock</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tlock</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function locks a type, making it read-only and non-destrucible. + This is normally done by the library for predefined data types so the + application doesn't inadvertently change or delete a predefined type. + Once a data type is locked it can never be unlocked. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to lock. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetClass">H5Tget_class</a> +<dt><strong>Signature:</strong> + <dd><em>H5T_class_t </em><code>H5Tget_class</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function returns the base class of a datatype. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + </dl> +<dt><strong>Returns:</strong> + <dd>Non-negative type class on success, negative on failure. +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetSize">H5Tget_size</a> +<dt><strong>Signature:</strong> + <dd><em>size_t </em><code>H5Tget_size</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function returns the size of a datatype in bytes. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + </dl> +<dt><strong>Returns:</strong> + <dd>Positve size in bytes on success, 0 on failure. +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-SetSize">H5Tset_size</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tset_size</code>(<em>hid_t </em><code>type_id</code>, + <em>size_t</em><code>size</code> + ) +<dt><strong>Description:</strong> + <dd>This function sets the total size in bytes for an atomic data type (this + operation is not permitted on compound data types). If the size is + decreased so that the significant bits of the data type extend beyond + the edge of the new size, then the `offset' property is decreased + toward zero. If the `offset' becomes zero and the significant + bits of the data type still hang over the edge of the new size, then + the number of significant bits is decreased. + Adjusting the size of an H5T_STRING automatically sets the precision + to 8*size. All data types have a positive size. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to change size. + <dt><em>size_t</em> <code>size</code> + <dd>Size in bytes to modify datatype. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetOrder">H5Tget_order</a> +<dt><strong>Signature:</strong> + <dd><em>H5T_order_t </em><code>H5Tget_order</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function returns the byte order of an atomic datatype. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + </dl> +<dt><strong>Returns:</strong> + <dd>Byte order constant on success, negative on failure +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-SetOrder">H5Tset_order</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tset_order</code>(<em>hid_t </em><code>type_id</code>, + <em>H5T_order_t</em><code>order</code> + ) +<dt><strong>Description:</strong> + <dd>This function sets the byte ordering of an atomic datatype. + Byte orderings currently supported are: + <ul> <dl> + <dt>H5T_ORDER_LE + <dd> Little-endian byte ordering (default) + <dt>H5T_ORDER_BE + <dd> Big-endian byte ordering + <dt>H5T_ORDER_Vax + <dd> VAX-endianness byte ordering (not currently supported) + </dl> </ul> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to set. + <dt><em>H5T_order_t</em> <code>order</code> + <dd>Byte ordering constant. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetPrecision">H5Tget_precision</a> +<dt><strong>Signature:</strong> + <dd><em>size_t </em><code>H5Tget_precision</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function returns the precision of an atomic data type. The + precision is the number of significant bits which, unless padding is + present, is 8 times larger than the value returned by H5Tget_size(). +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + </dl> +<dt><strong>Returns:</strong> + <dd>Number of significant bits on success, 0 on failure +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-SetPrecision">H5Tset_precision</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tset_precision</code>(<em>hid_t </em><code>type_id</code>, + <em>size_t</em><code>precision</code> + ) +<dt><strong>Description:</strong> + <dd>This function sets the precision of an atomic data type. The precision + is the number of significant bits which, unless padding is present, is 8 + times larger than the value returned by H5Tget_size(). + <P>If the precision is increased then the offset is decreased and then + the size is increased to insure that significant bits do not "hang + over" the edge of the data type. + <P>Changing the precision of an H5T_STRING automatically changes the + size as well. The precision must be a multiple of 8. + <P>When decreasing the precision of a floating point type, set the + locations and sizes of the sign, mantissa, and exponent fields + first. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to set. + <dt><em>size_t</em> <code>precision</code> + <dd>Number of bits of precision for datatype. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetOffset">H5Tget_offset</a> +<dt><strong>Signature:</strong> + <dd><em>size_t </em><code>H5Tget_offset</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function retrieves the bit offset of the first significant bit. + The signficant bits of an atomic datum can be offset from the beginning + of the memory for that datum by an amount of padding. The `offset' + property specifies the number of bits of padding that appear to the + "right of" the value. That is, if we have a 32-bit datum with 16-bits + of precision having the value 0x1122 then it will be layed out in + memory as (from small byte address toward larger byte addresses): + <br> + <br> + + <table border align=center cellpadding=4 width="80%"> + <tr align=center> + <th width="20%">Byte Position</th> + <th width="20%">Big-Endian Offset=0</th> + <th width="20%">Big-Endian Offset=16</th> + <th width="20%">Little-Endian Offset=0</th> + <th width="20%">Little-Endian Offset=16</th> + </tr> + <tr align=center> + <td>0:</td> + <td>[ pad]</td> + <td>[0x11]</td> + <td>[0x22]</td> + <td>[ pad]</td> + </tr> + <tr align=center> + <td>1:</td> + <td>[ pad]</td> + <td>[0x22]</td> + <td>[0x11]</td> + <td>[ pad]</td> + </tr> + <tr align=center> + <td>2:</td> + <td>[0x11]</td> + <td>[ pad]</td> + <td>[ pad]</td> + <td>[0x22]</td> + </tr> + <tr align=center> + <td>3:</td> + <td>[0x22]</td> + <td>[ pad]</td> + <td>[ pad]</td> + <td>[0x11]</td> + </tr> + </table> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + </dl> +<dt><strong>Returns:</strong> + <dd>Positive offset value on success, 0 on failure. +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-SetOffset">H5Tset_offset</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tset_offset</code>(<em>hid_t </em><code>type_id</code>, + <em>size_t</em> <code>offset</code> + ) +<dt><strong>Description:</strong> + <dd>This function sets the bit offset of the first significant bit. The + signficant bits of an atomic datum can be offset from the beginning of + the memory for that datum by an amount of padding. The `offset' + property specifies the number of bits of padding that appear to the + "right of" the value. That is, if we have a 32-bit datum with 16-bits + of precision having the value 0x1122 then it will be layed out in + memory as (from small byte address toward larger byte addresses): + <br> + <br> + + <table border align=center cellpadding=4 width="80%"> + <tr align=center> + <th width="20%">Byte Position</th> + <th width="20%">Big-Endian Offset=0</th> + <th width="20%">Big-Endian Offset=16</th> + <th width="20%">Little-Endian Offset=0</th> + <th width="20%">Little-Endian Offset=16</th> + </tr> + <tr align=center> + <td>0:</td> + <td>[ pad]</td> + <td>[0x11]</td> + <td>[0x22]</td> + <td>[ pad]</td> + </tr> + <tr align=center> + <td>1:</td> + <td>[ pad]</td> + <td>[0x22]</td> + <td>[0x11]</td> + <td>[ pad]</td> + </tr> + <tr align=center> + <td>2:</td> + <td>[0x11]</td> + <td>[ pad]</td> + <td>[ pad]</td> + <td>[0x22]</td> + </tr> + <tr align=center> + <td>3:</td> + <td>[0x22]</td> + <td>[ pad]</td> + <td>[ pad]</td> + <td>[0x11]</td> + </tr> + </table> + +<P>If the offset is incremented then the total size is +incremented also if necessary to prevent significant bits of +the value from hanging over the edge of the data type. + +<P>The offset of an H5T_STRING cannot be set to anything but +zero. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to set. + <dt><em>size_t</em> <code>offset</code> + <dd>Offset of first significant bit. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetPad">H5Tget_pad</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tget_pad</code>(<em>hid_t </em><code>type_id</code>, + <em>H5T_pad_t *</em> <code>lsb</code>, + <em>H5T_pad_t *</em> <code>msb</code> + ) +<dt><strong>Description:</strong> + <dd>This function retrieves the padding type of the least and most-significant + bit padding. Valid types are: + <ul> <dl> + <dt>H5T_PAD_ZERO + <dd>Set background to zeros. + <dt>H5T_PAD_ONE + <dd>Set background to ones. + <dt>H5T_PAD_BACKGROUND + <dd>Leave background alone. + </dl> </ul> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + <dt><em>H5T_pad_t *</em> <code>lsb</code> + <dd>Pointer to location to return least-significant bit padding type. + <dt><em>H5T_pad_t *</em> <code>msb</code> + <dd>Pointer to location to return most-significant bit padding type. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-SetPad">H5Tset_pad</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tset_pad</code>(<em>hid_t </em><code>type_id</code>, + <em>H5T_pad_t</em> <code>lsb</code>, + <em>H5T_pad_t</em> <code>msb</code> + ) +<dt><strong>Description:</strong> + <dd>This function sets the least and most-significant bits padding types. + <ul> <dl> + <dt>H5T_PAD_ZERO + <dd>Set background to zeros. + <dt>H5T_PAD_ONE + <dd>Set background to ones. + <dt>H5T_PAD_BACKGROUND + <dd>Leave background alone. + </dl> </ul> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to set. + <dt><em>H5T_pad_t</em> <code>lsb</code> + <dd>Padding type for least-significant bits. + <dt><em>H5T_pad_t</em> <code>msb</code> + <dd>Padding type for most-significant bits. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetSign">H5Tget_sign</a> +<dt><strong>Signature:</strong> + <dd><em>H5T_sign_t </em><code>H5Tget_sign</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function retrieves the sign type for an integer type. + Valid types are: + <ul> <dl> + <dt>H5T_SGN_NONE + <dd>Unsigned integer type. + <dt>H5T_SGN_2 + <dd>Two's complement signed integer type. + </dl> </ul> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + </dl> +<dt><strong>Returns:</strong> + <dd>Non-negative sign type on success, negative on failure +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-SetSign">H5Tset_sign</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tset_sign</code>(<em>hid_t </em><code>type_id</code>, + <em>H5T_sign_t</em> <code>sign</code> + ) +<dt><strong>Description:</strong> + <dd>This function sets the sign proprety for an integer type. + <ul> <dl> + <dt>H5T_SGN_NONE + <dd>Unsigned integer type. + <dt>H5T_SGN_2 + <dd>Two's complement signed integer type. + </dl> </ul> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to set. + <dt><em>H5T_sign_t</em> <code>sign</code> + <dd>Sign type. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetFields">H5Tget_fields</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tget_fields</code>(<em>hid_t </em><code>type_id</code>, + <em>size_t *</em> <code>epos</code>, + <em>size_t *</em> <code>esize</code>, + <em>size_t *</em> <code>mpos</code>, + <em>size_t *</em> <code>msize</code> + ) +<dt><strong>Description:</strong> + <dd>This function retrieves information about the locations of the various + bit fields of a floating point data type. The field positions are bit + positions in the significant region of the data type. Bits are + numbered with the least significant bit number zero. + Any (or even all) of the arguments can be null pointers. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + <dt><em>size_t *</em> <code>epos</code> + <dd>Pointer to location to return exponent bit-position. + <dt><em>size_t *</em> <code>esize</code> + <dd>Pointer to location to return size of exponent in bits. + <dt><em>size_t *</em> <code>mpos</code> + <dd>Pointer to location to return mantissa bit-position. + <dt><em>size_t *</em> <code>msize</code> + <dd>Pointer to location to return size of mantissa in bits. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-SetFields">H5Tset_fields</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tset_fields</code>(<em>hid_t </em><code>type_id</code>, + <em>size_t</em> <code>epos</code>, + <em>size_t</em> <code>esize</code>, + <em>size_t</em> <code>mpos</code>, + <em>size_t</em> <code>msize</code> + ) +<dt><strong>Description:</strong> + <dd>This function sets the locations and sizes of the various floating + point bit fields. The field positions are bit positions in the + significant region of the data type. Bits are numbered with the least + significant bit number zero. + + <P>Fields are not allowed to extend beyond the number of bits of + precision, nor are they allowed to overlap with one another. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to set. + <dt><em>size_t</em> <code>epos</code> + <dd>Exponent bit position. + <dt><em>size_t</em> <code>esize</code> + <dd>Size of exponent in bits. + <dt><em>size_t</em> <code>mpos</code> + <dd>Mantissa bit position. + <dt><em>size_t</em> <code>msize</code> + <dd>Size of mantissa in bits. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetEbias">H5Tget_ebias</a> +<dt><strong>Signature:</strong> + <dd><em>size_t </em><code>H5Tget_ebias</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function retrieves the exponent bias of a floating-point type. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + </dl> +<dt><strong>Returns:</strong> + <dd>Positive value on success, 0 on failure. +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-SetEbias">H5Tset_ebias</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tset_ebias</code>(<em>hid_t </em><code>type_id</code>, + <em>size_t</em> <code>ebias</code> + ) +<dt><strong>Description:</strong> + <dd>This function sets the exponent bias of a floating-point type. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to set. + <dt><em>size_t</em> <code>ebias</code> + <dd>Exponent bias value. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetNorm">H5Tget_norm</a> +<dt><strong>Signature:</strong> + <dd><em>H5T_norm_t </em><code>H5Tget_norm</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function retrieves the mantissa normalization of a floating-point + datatype. Valid normalization values are: + <ul> <dl> + <dt>H5T_NORM_IMPLIED + <dd>MSB of mantissa isn't stored, always 1 + <dt>H5T_NORM_MSBSET + <dd>MSB of mantissa is always 1 + <dt>H5T_NORM_NONE + <dd>Mantissa is not normalized + </dl> </ul> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + </dl> +<dt><strong>Returns:</strong> + <dd>Non-negative normalization type on success, negative on failure +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-SetNorm">H5Tset_norm</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tset_norm</code>(<em>hid_t </em><code>type_id</code>, + <em>H5T_norm_t</em> <code>norm</code> + ) +<dt><strong>Description:</strong> + <dd>This function sets the mantissa normalization of a floating-point + datatype. Valid normalization values are: + <ul> <dl> + <dt>H5T_NORM_IMPLIED + <dd>MSB of mantissa isn't stored, always 1 + <dt>H5T_NORM_MSBSET + <dd>MSB of mantissa is always 1 + <dt>H5T_NORM_NONE + <dd>Mantissa is not normalized + </dl> </ul> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to set. + <dt><em>H5T_norm_t</em> <code>norm</code> + <dd>Mantissa normalization type. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetInpad">H5Tget_inpad</a> +<dt><strong>Signature:</strong> + <dd><em>H5T_pad_t </em><code>H5Tget_inpad</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function retrieves the internal padding type for unused bits in + floating-point datatypes. + Valid padding values are: + <ul> <dl> + <dt>H5T_PAD_ZERO + <dd>Set background to zeros. + <dt>H5T_PAD_ONE + <dd>Set background to ones. + <dt>H5T_PAD_BACKGROUND + <dd>Leave background alone. + </dl> </ul> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + </dl> +<dt><strong>Returns:</strong> + <dd>Non-negative padding type on success, negative on failure +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-SetInpad">H5Tset_inpad</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tset_inpad</code>(<em>hid_t </em><code>type_id</code>, + <em>H5T_pad_t</em> <code>inpad</code> + ) +<dt><strong>Description:</strong> + <dd>If any internal bits of a floating point type are unused + (that is, those significant bits which are not part of the + sign, exponent, or mantissa) then they will be filled + according to the value of this property. + Valid padding values are: + <ul> <dl> + <dt>H5T_PAD_ZERO + <dd>Set background to zeros. + <dt>H5T_PAD_ONE + <dd>Set background to ones. + <dt>H5T_PAD_BACKGROUND + <dd>Leave background alone. + </dl> </ul> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to modify. + <dt><em>H5T_pad_t</em> <code>pad</code> + <dd>Padding type. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetCset">H5Tget_cset</a> +<dt><strong>Signature:</strong> + <dd><em>H5T_cset_t </em><code>H5Tget_cset</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function retrieves the character set type of a string datatype. + Valid character set values are: + <ul> <dl> + <dt>H5T_CSET_ASCII + <dd>Character set is US ASCII + </dl> </ul> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + </dl> +<dt><strong>Returns:</strong> + <dd>Non-negative character set type on success, negative on failure +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-SetCset">H5Tset_cset</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tset_cset</code>(<em>hid_t </em><code>type_id</code>, + <em>H5T_cset_t</em> <code>cset</code> + ) +<dt><strong>Description:</strong> + <dd>HDF5 is able to distinguish between character sets of different + nationalities and to convert between them to the extent possible. + Valid character set values are: + <ul> <dl> + <dt>H5T_CSET_ASCII + <dd>Character set is US ASCII + </dl> </ul> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to modify. + <dt><em>H5T_cset_t</em> <code>cset</code> + <dd>Character set type. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetStrpad">H5Tget_strpad</a> +<dt><strong>Signature:</strong> + <dd><em>H5T_str_t </em><code>H5Tget_strpad</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function retrieves the string padding method for a string datatype. + Valid string padding values are: + <ul> <dl> + <dt>H5T_STR_NULL + <dd>Pad with zeros (as C does) + <dt>H5T_STR_SPACE + <dd>Pad with spaces (as FORTRAN does) + </dl> </ul> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + </dl> +<dt><strong>Returns:</strong> + <dd>Non-negative string padding type on success, negative on failure +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-SetStrpad">H5Tset_strpad</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tset_strpad</code>(<em>hid_t </em><code>type_id</code>, + <em>H5T_str_t</em> <code>strpad</code> + ) +<dt><strong>Description:</strong> + <dd>The method used to store character strings differs with the programming + language: C usually null terminates strings while Fortran + left-justifies and space-pads strings. This property defines the + storage mechanism for the string. + Valid string padding values are: + <ul> <dl> + <dt>H5T_STR_NULL + <dd>Pad with zeros (as C does) + <dt>H5T_STR_SPACE + <dd>Pad with spaces (as FORTRAN does) + </dl> </ul> +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to modify. + <dt><em>H5T_str_t</em> <code>strpad</code> + <dd>String padding type. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetNmembers">H5Tget_nmembers</a> +<dt><strong>Signature:</strong> + <dd><em>intn </em><code>H5Tget_nmembers</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function retrieves the number of fields a compound datatype has. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + </dl> +<dt><strong>Returns:</strong> + <dd>Number of members datatype has on success, negative on failure +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetMemberName">H5Tget_member_name</a> +<dt><strong>Signature:</strong> + <dd><em>char *</em> <code>H5Tget_member_name</code>(<em>hid_t </em><code>type_id</code>, + <em>intn</em> <code>fieldno</code> + ) +<dt><strong>Description:</strong> + <dd>This function retrieves the name of a field of a compound data type. + Fields are stored in no particular order with numbers 0 through N-1 + where N is the value returned by H5Tget_nmembers(). The name of the + field is allocated with malloc() and the caller is responsible for + freeing the memory used by the name. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + <dt><em>intn</em> <code>fieldno</code> + <dd>Field number (indexed from 0) of the field name to retrieve. + </dl> +<dt><strong>Returns:</strong> + <dd>Valid pointer on success, NULL on failure +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetMemberDims">H5Tget_member_dims</a> +<dt><strong>Signature:</strong> + <dd><em>int</em> <code>H5Tget_member_dims</code>(<em>hid_t </em><code>type_id</code>, + <em>intn</em> <code>fieldno</code>, + <em>size_t *</em> <code>dims</code>, + <em>int *</em> <code>perm</code> + ) +<dt><strong>Description:</strong> + <dd>This function returns the dimensionality of the field. The dimensions + and permuation vector are returned through arguments <code>dims</code> + and <code>perm</code>, both arrays of at least four elements. Either + (or even both) may be null pointers. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + <dt><em>intn</em> <code>fieldno</code> + <dd>Field number (indexed from 0) of the field dims to retrieve. + <dt><em>size_t *</em> <code>dims</code> + <dd>Pointer to buffer to store the dimensions of the field. + <dt><em>int *</em> <code>perm</code> + <dd>Pointer to buffer to store the permutation vector of the field. + </dl> +<dt><strong>Returns:</strong> + <dd>Number of dimensions on success, negative on failure. +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-GetMemberType">H5Tget_member_type</a> +<dt><strong>Signature:</strong> + <dd><em>hid_t</em> <code>H5Tget_member_type</code>(<em>hid_t </em><code>type_id</code>, + <em>intn</em> <code>fieldno</code> + ) +<dt><strong>Description:</strong> + <dd>This function returns the data type of the specified member. The caller + should invoke H5Tclose() to release resources associated with the type. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to query. + <dt><em>intn</em> <code>fieldno</code> + <dd>Field number (indexed from 0) of the field type to retrieve. + </dl> +<dt><strong>Returns:</strong> + <dd>The ID of a copy of the datatype of the field, negative on failure. +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-Insert">H5Tinsert</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t</em> <code>H5Tinsert</code>(<em>hid_t </em><code>type_id</code>, + <em>const char *</em> <code>name</code>, + <em>off_t</em> <code>offset</code>, + <em>hid_t</em> <code>field_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function adds another member to the compound data type + <code>type_id</code>. The new member has a <code>name</code> which + must be unique within the compound data type. The <code>offset</code> + argument defines the start of the member in an instance of the compound + data type, and <code>field_id</code> is the type of the new member. + + <P>Note: All members of a compound data type must be atomic; a + compound data type cannot have a member which is a compound data + type. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of compound datatype to modify. + <dt><em>const char *</em> <code>name</code> + <dd>Name of the field to insert. + <dt><em>off_t</em> <code>offset</code> + <dd>Offset in memory structure of the field to insert. + <dt><em>hid_t</em> <code>field_id</code> + <dd>Datatype ID of the field to insert. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-Pack">H5Tpack</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t</em> <code>H5Tpack</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function recursively removes padding from within a compound + datatype to make it more efficient (space-wise) to store that data. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to modify. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-RegisterHard">H5Tregister_hard</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t</em> <code>H5Tregister_hard</code>(<em>const char + *</em> <code>name</code>, <em>hid_t </em><code>src_id</code>, + <em>hid_t</em> <code>dst_id</code>, + <em>H5T_conv_t</em> <code>func</code> + ) +<dt><strong>Description:</strong> + <dd>This function registers a hard conversion function for a data type + conversion path. The path is specified by the source and destination + datatypes <code>src_id</code> and <code>dst_id</code>. A conversion + path can only have one hard function, so <code>func</code> replaces any + previous hard function. + <P>If <code>func</code> is the null pointer then any hard function + registered for this path is removed from this path. The soft functions + are then used when determining which conversion function is appropriate + for this path. The <code>name</code> argument is used only + for debugging and should be a short identifier for the function. + <P>The type of the conversion function pointer is declared as: + typedef herr_t (*H5T_conv_t) (hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, + size_t nelmts, void *buf, void *bkg); +<dt><strong>Parameters:</strong> + <dl> + <dt><em>const char *</em> <code>name</code> + <dd>Name displayed in diagnostic output. + <dt><em>hid_t</em> <code>src_id</code> + <dd>ID of source datatype. + <dt><em>hid_t</em> <code>dst_id</code> + <dd>ID of destination datatype. + <dt><em>H5T_conv_t</em> <code>func</code> + <dd>Function to convert between source and destination datatypes. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-RegisterSoft">H5Tregister_soft</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t</em> <code>H5Tregister_soft</code>(<em>const char + *</em> <code>name</code>, <em>hid_t </em><code>src_id</code>, + <em>hid_t</em> <code>dst_id</code>, + <em>H5T_conv_t</em> <code>func</code> + ) +<dt><strong>Description:</strong> + <dd>This function registers a soft conversion function by adding it to the + end of the master soft list and replacing the soft function in all + applicable existing conversion paths. The <code>name</code> + is used only for debugging and should be a short identifier + for the function. + <P>The type of the conversion function pointer is declared as: + typedef herr_t (*H5T_conv_t) (hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, + size_t nelmts, void *buf, void *bkg); +<dt><strong>Parameters:</strong> + <dl> + <dt><em>const char *</em> <code>name</code> + <dd>Name displayed in diagnostic output. + <dt><em>hid_t</em> <code>src_id</code> + <dd>ID of source datatype. + <dt><em>hid_t</em> <code>dst_id</code> + <dd>ID of destination datatype. + <dt><em>H5T_conv_t</em> <code>func</code> + <dd>Function to convert between source and destination datatypes. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-Unregister">H5Tunregister</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t</em> <code>H5Tunregister</code>(<em>H5T_conv_t</em> <code>func</code> + ) +<dt><strong>Description:</strong> + <dd>This function removes a conversion function from all conversion paths. + <P>The type of the conversion function pointer is declared as: + typedef herr_t (*H5T_conv_t) (hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, + size_t nelmts, void *buf, void *bkg); +<dt><strong>Parameters:</strong> + <dl> + <dt><em>H5T_conv_t</em> <code>func</code> + <dd>Function to remove from conversion paths. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + +<hr> +<dl> +<dt><strong>Name:</strong> <a name="Datatype-Close">H5Tclose</a> +<dt><strong>Signature:</strong> + <dd><em>herr_t </em><code>H5Tclose</code>(<em>hid_t </em><code>type_id</code> + ) +<dt><strong>Description:</strong> + <dd>This function releases a datatype. Further access through the datatype + ID is illegal. Failure to release a datatype with this call will + result in resource leaks. +<dt><strong>Parameters:</strong> + <dl> + <dt><em>hid_t</em> <code>type_id</code> + <dd>ID of datatype to release. + </dl> +<dt><strong>Returns:</strong> + <dd>zero/negative +</dl> + + + +<hr> +<hr> +</b>UNUSED PORTIONS OF EMAIL NOTES.</b> +<br> +<code>....</code> in left margin indicates where material was + pulled out for inclusion above. +<HR> +<HR> +<pre> + +Elena> Datatype Interface: +Elena> Do we have description of the named datatypes somewhere? + +>From Datatypes.html... + +html> 7. Sharing Data Types among Datasets +html> +html> If a file has lots of datasets which have a common data type +html> then the file could be made smaller by having all the datasets +html> share a single data type. Instead of storing a copy of the data +html> type in each dataset object header, a single data type is stored +html> and the object headers point to it. The space savings is +html> probably only significant for datasets with a compound data type +html> since the simple data types can be described with just a few +html> bytes anyway. +html> +html> To create a bunch of datasets that share a single data type just +html> create the datasets with a committed (named) data type. +html> +html> To create two datasets that share a common data type one just +html> commits the data type, giving it a name, and then uses that +html> data type to create the datasets. +html> +html> hid_t t1 = ...some transient type...; +html> H5Tcommit (file, "shared_type", t1); +html> hid_t dset1 = H5Dcreate (file, "dset1", t1, space, H5P_DEFAULT); +html> hid_t dset2 = H5Dcreate (file, "dset2", t1, space, H5P_DEFAULT); +html> +html> +html> And to create two additional datasets later which share the +html> same type as the first two datasets: +html> +html> hid_t dset1 = H5Dopen (file, "dset1"); +html> hid_t t2 = H5Dget_type (dset1); +html> hid_t dset3 = H5Dcreate (file, "dset3", t2, space, H5P_DEFAULT); +html> hid_t dset4 = H5Dcreate (file, "dset4", t2, space, H5P_DEFAULT); +html> +html> +html> Example: Shared Types + +Mail from Quincey summarizing shared data types: + +Quincey> Hi Robb, +Quincey> Everything looks good, I just have a couple of minor comments below: +Quincey> +Quincey> > A very quick data types summary (so I can remember it next week :-) +Quincey> > +Quincey> > * Handles to named types are immutable. +Quincey> > +Quincey> > * A transient type handle can be converted to a named type handle +Quincey> > by calling H5Tcommit(). This can only be called for transient +Quincey> > types which are not locked or predefined. +Quincey> > +Quincey> > * H5Topen() returns a handle to a named immutable type. +Quincey> > +Quincey> > * H5Tcopy() returns a handle to a transient type. +Quincey> H5Tcreate also returns a handle to a transient type. +Quincey> +Quincey> > * Using a named type in H5Dcreate() causes the dataset object +Quincey> > header to point to the named type (shared). The link count on +Quincey> > the named type is incremented. +Quincey> > +Quincey> > * Using a transient type in H5Dcreate() causes the type to be +Quincey> > copied and stored in the dataset header (unshared). +Quincey> > +Quincey> > * Type handles returned from H5Dget_type() are immutable. +Quincey> > +Quincey> > * If the dataset is using a shared type (dataset object header +Quincey> > points to some other object header with a type message, e.g., a +Quincey> > named type) then H5Dget_type() returns a handle to that named +Quincey> > type. +Quincey> > +Quincey> > * If the dataset has a private type (data type is stored in the +Quincey> > dataset object header) then H5Dget_type() returns a handle to a +Quincey> > transient immutable type. +Quincey> > +Quincey> > * The name of a data type can be removed from a group, but unless +Quincey> > the reference count becomes zero the type continues to exist. +Quincey> > (Other objects work this way too). +Quincey> > +Quincey> > * H5Tcopy() applied to a dataset returns a transient, modifiable +Quincey> > copy of that dataset's data type. +Quincey> > +Quincey> > * H5Topen() applied to a dataset returns either a transient +Quincey> > immutable or named immutable data type depending on whether the +Quincey> > dataset has a shared data type. +Quincey> Hmm, do we want to allow this? It makes a certain amount of sense, but +Quincey> is a little unusual... :-) +Quincey> + +Elena, we decided not not to allow H5Topen() on a dataset. + +Quincey> +Quincey> > * The H5Tshare() and H5Tis_shared() will be removed. Data types +Quincey> > will not be stored in the global heap. A new type of shared +Quincey> > message header will be added to the object headers that points to +Quincey> > another object header instead of the global heap +Quincey> +Quincey> > * Still to discuss: Attributes on named data types? +Quincey> I think we should all them. +Quincey> + +Elena, attributes work for named data types just like they do for +datasets. + +Quincey> +Quincey> > * Still to discuss: compound types whose members point to other types. +Quincey> I like this concept a lot and this we should figure out a way to do it. +Quincey> This allows the "is a" relationship to be used very nicely for named datatypes. +Quincey> +Quincey> > * Still to discuss: datasets that point to data types in other +Quincey> > files by symbolic link. +Quincey> Probably a good idea also, just ugly to implement. +Quincey> + +</pre> +<hr> +<hr> + + + + +<hr> + +<address> +<a href="mailto:fbaker@ncsa.uiuc.edu">Frank Baker</a> +<br> +<a href="mailto:h5docs@ncsa.uiuc.edu">HDF5 Documentation</a> + +<br> +Last modified: 29 June 1998 + +</body> +</html> |