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SDreadchunk
intn SDreadchunk(int32
sds_id
, int32 *
origin
, VOIDP
datap
)
sds_id
IN:
SD interface identifier returned from
SDstart
origin
IN:
Origin of the chunk to be read
datap
OUT:
Buffer for the returned chunk data
Purpose
Reads data from a chunked scientific dataset.
Return value
Returns SUCCEED (or 0) if successful and FAIL (or -1) otherwise.
Description
SDreadchunk
is used when an entire chunk of data is to be read.
SDreaddata
is used when the read operation is to be done regardless of the chunking scheme used in the SDS.
Also,
SDreadchunk
is written specifically for chunked SDSs and and doesn't have the overhead of the additional functionality supported by the
SDreaddata
routine - therefore, it is much faster than
SDreaddata
.
SDreadchunk
will return FAIL when an attempt is made to use it to read from a non-chunked SDS.
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HDF User's Reference Manual, Draft 06/09/97, NCSA HDF Development Group.