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+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by the Board of Trustees of the University of Illinois. *
+ * All rights reserved. *
+ * *
+ * This file is part of HDF5. The full HDF5 copyright notice, including *
+ * terms governing use, modification, and redistribution, is contained in *
+ * the files COPYING and Copyright.html. COPYING can be found at the root *
+ * of the source code distribution tree; Copyright.html can be found at the *
+ * root level of an installed copy of the electronic HDF5 document set and *
+ * is linked from the top-level documents page. It can also be found at *
+ * http://hdf.ncsa.uiuc.edu/HDF5/doc/Copyright.html. If you do not have *
+ * access to either file, you may request a copy from hdfhelp@ncsa.uiuc.edu. *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*
+ * Module Info: This module contains the functionality for setting & querying
+ * the datatype offset for the H5T interface.
+ */
+
+#define H5T_PACKAGE /*suppress error about including H5Tpkg */
+
+#include "H5private.h" /*generic functions */
+#include "H5Eprivate.h" /*error handling */
+#include "H5Iprivate.h" /*ID functions */
+#include "H5Tpkg.h" /*data-type functions */
+
+#define PABLO_MASK H5Toffset_mask
+
+/* Interface initialization */
+static int interface_initialize_g = 0;
+#define INTERFACE_INIT H5T_init_offset_interface
+static herr_t H5T_init_offset_interface(void);
+
+/* Static local functions */
+static herr_t H5T_set_offset(H5T_t *dt, size_t offset);
+
+
+/*--------------------------------------------------------------------------
+NAME
+ H5T_init_offset_interface -- Initialize interface-specific information
+USAGE
+ herr_t H5T_init_offset_interface()
+
+RETURNS
+ Non-negative on success/Negative on failure
+DESCRIPTION
+ Initializes any interface-specific data or routines. (Just calls
+ H5T_init_iterface currently).
+
+--------------------------------------------------------------------------*/
+static herr_t
+H5T_init_offset_interface(void)
+{
+ FUNC_ENTER_NOINIT(H5T_init_offset_interface);
+
+ FUNC_LEAVE_NOAPI(H5T_init_interface());
+} /* H5T_init_offset_interface() */
+
+
+/*-------------------------------------------------------------------------
+ * Function: H5Tget_offset
+ *
+ * Purpose: 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):
+ *
+ * Big Big Little Little
+ * Endian Endian Endian Endian
+ * offset=0 offset=16 offset=0 offset=16
+ *
+ * 0: [ pad] [0x11] [0x22] [ pad]
+ * 1: [ pad] [0x22] [0x11] [ pad]
+ * 2: [0x11] [ pad] [ pad] [0x22]
+ * 3: [0x22] [ pad] [ pad] [0x11]
+ *
+ * Return: Success: The offset (non-negative)
+ *
+ * Failure: Negative
+ *
+ * Programmer: Robb Matzke
+ * Wednesday, January 7, 1998
+ *
+ * Modifications:
+ * Robb Matzke, 22 Dec 1998
+ * Also works for derived data types.
+ *
+ *-------------------------------------------------------------------------
+ */
+int
+H5Tget_offset(hid_t type_id)
+{
+ H5T_t *dt = NULL;
+ int ret_value;
+
+ FUNC_ENTER_API(H5Tget_offset, -1);
+ H5TRACE1("Is","i",type_id);
+
+ /* Check args */
+ if (NULL == (dt = H5I_object_verify(type_id,H5I_DATATYPE)))
+ HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an atomic data type");
+ if (dt->parent)
+ dt = dt->parent; /*defer to parent*/
+ if (H5T_COMPOUND==dt->type || H5T_OPAQUE==dt->type || H5T_ARRAY==dt->type)
+ HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "operation not defined for specified data type");
+
+ /* Offset */
+ assert(H5T_is_atomic(dt));
+ ret_value = (int)dt->u.atomic.offset;
+
+done:
+ FUNC_LEAVE_API(ret_value);
+}
+
+
+/*-------------------------------------------------------------------------
+ * Function: H5Tset_offset
+ *
+ * Purpose: 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):
+ *
+ * Big Big Little Little
+ * Endian Endian Endian Endian
+ * offset=0 offset=16 offset=0 offset=16
+ *
+ * 0: [ pad] [0x11] [0x22] [ pad]
+ * 1: [ pad] [0x22] [0x11] [ pad]
+ * 2: [0x11] [ pad] [ pad] [0x22]
+ * 3: [0x22] [ pad] [ pad] [0x11]
+ *
+ * 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.
+ *
+ * The offset of an H5T_STRING cannot be set to anything but
+ * zero.
+ *
+ * Return: Non-negative on success/Negative on failure
+ *
+ * Programmer: Robb Matzke
+ * Wednesday, January 7, 1998
+ *
+ * Modifications:
+ * Robb Matzke, 22 Dec 1998
+ * Moved real work to a private function.
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Tset_offset(hid_t type_id, size_t offset)
+{
+ H5T_t *dt = NULL;
+ herr_t ret_value=SUCCEED; /* Return value */
+
+ FUNC_ENTER_API(H5Tset_offset, FAIL);
+ H5TRACE2("e","iz",type_id,offset);
+
+ /* Check args */
+ if (NULL == (dt = H5I_object_verify(type_id,H5I_DATATYPE)))
+ HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an atomic data type");
+ if (H5T_STATE_TRANSIENT!=dt->state)
+ HGOTO_ERROR(H5E_ARGS, H5E_CANTINIT, FAIL, "data type is read-only");
+ if (H5T_STRING == dt->type && offset != 0)
+ HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "offset must be zero for this type");
+ if (H5T_ENUM==dt->type && dt->u.enumer.nmembs>0)
+ HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "operation not allowed after members are defined");
+
+ /* Do the real work */
+ if (H5T_set_offset(dt, offset)<0)
+ HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to set offset");
+
+done:
+ FUNC_LEAVE_API(ret_value);
+}
+
+
+/*-------------------------------------------------------------------------
+ * Function: H5T_set_offset
+ *
+ * Purpose: 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):
+ *
+ * Big Big Little Little
+ * Endian Endian Endian Endian
+ * offset=0 offset=16 offset=0 offset=16
+ *
+ * 0: [ pad] [0x11] [0x22] [ pad]
+ * 1: [ pad] [0x22] [0x11] [ pad]
+ * 2: [0x11] [ pad] [ pad] [0x22]
+ * 3: [0x22] [ pad] [ pad] [0x11]
+ *
+ * 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.
+ *
+ * The offset of an H5T_STRING cannot be set to anything but
+ * zero.
+ *
+ * Return: Non-negative on success/Negative on failure
+ *
+ * Programmer: Robb Matzke
+ * Wednesday, January 7, 1998
+ *
+ * Modifications:
+ * Robb Matzke, 22 Dec 1998
+ * Also works for derived data types.
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5T_set_offset(H5T_t *dt, size_t offset)
+{
+ herr_t ret_value=SUCCEED; /* Return value */
+
+ FUNC_ENTER_NOAPI(H5T_set_offset, FAIL);
+
+ /* Check args */
+ assert(dt);
+ assert(H5T_STRING!=dt->type || 0==offset);
+ assert(H5T_ENUM!=dt->type || 0==dt->u.enumer.nmembs);
+
+ if (dt->parent) {
+ if (H5T_set_offset(dt->parent, offset)<0)
+ HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to set offset for base type");
+ dt->size = dt->parent->size;
+ } else {
+ if (H5T_COMPOUND==dt->type || H5T_OPAQUE==dt->type || H5T_ARRAY==dt->type) {
+ HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "operation not defined for specified data type");
+ } else if (H5T_ENUM==dt->type) {
+ /*nothing*/
+ } else {
+ if (offset+dt->u.atomic.prec > 8*dt->size) {
+ dt->size = (offset + dt->u.atomic.prec + 7) / 8;
+ }
+ dt->u.atomic.offset = offset;
+ }
+ }
+
+done:
+ FUNC_LEAVE_NOAPI(ret_value);
+}
+
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