Scatters data into a selection within a memory buffer
H5D_SCATTER(op, op_data,type_id, dst_space_id,dst_buf)
herr_t H5Dscatter( H5D_scatter_func_t op, void * op_data, hid_t type_id, hid_t dst_space_id, void *dst_buf )
|H5D_scatter_func_t ||IN: Callback function which provides data to be scattered|
|void *||IN: User-defined pointer to data required by |
IN: Identifier for the datatype describing the data in both the source and definition buffers
This is only used to calculate the element size.
|hid_t ||IN: Identifier for the dataspace describing both the dimensions of the destination buffer and the selection within the destination buffer that data will be scattered to|
|void *||OUT: Destination buffer which the data will be scattered to|
H5D_SCATTER retrieves data from the supplied callback
op and scatters it to the supplied buffer
dst_buf in a manner similar to data being written to a dataset.
dst_space_id is a dataspace which defines the extent of
dst_buf and the selection within it to scatter the data to.
type_id is the datatype of the data to be scattered in both the source and destination buffers.
dst_buf must be at least as large as the number of elements in the extent of
dst_space_id times the size in bytes of
To retrieve the data to be scattered, H5D_SCATTER repeatedly calls
op, which should return a valid source buffer, until enough data to fill the selection has been retrieved. The prototype of the callback function
op is as follows (as defined in the source code file
(*H5D_scatter_func_t)( const void **
src_buf/*out*/, size_t *
src_buf_bytes_used/*out*/, void *
The parameters of this callback function have the following values or meanings:
|Pointer to the buffer holding the next set of elements to scatter|
On entry, the value of
|Pointer to the number of valid bytes in |
On entry, the value of
User-defined pointer to data required by the callback function
A pass-through of the
The callback function should always return at least one element in
src_buf, and must not return more elements than are remaining to be scattered. This function will be repeatedly called until all elements to be scattered have been returned. The callback function should return zero (
0) to indicate success, and a negative value to indicate failure.
Note for C++ Developers Using C Functions:
If a C routine that takes a function pointer as an argument is called from within C++ code, the C routine should be returned from normally.
Examples of this kind of routine include callbacks such as H5P_SET_ELINK_CB and H5P_SET_TYPE_CONV_CB and functions such as H5T_CONVERT and H5E_WALK2.
Exiting the routine in its normal fashion allows the HDF5 C library to clean up its work properly. In other words, if the C++ application jumps out of the routine back to the C++ “catch” statement, the HDF5 C library is not given the opportunity to close any temporary data structures that were set up when the routine was called. The C++ application should save some state as the routine is started so that any problem that occurs might be diagnosed.
Returns a non-negative value if successful; otherwise returns a negative value.
|1.8.11||C function introduced.|