more documentation for nc_inq_var_szip
@@ -660,15 +660,17 @@ nc_inq_var_filter(int ncid, int varid, unsigned int* idp, size_t* nparamsp, unsi
idp, nparamsp, params);
}
-/** \ingroup variables
+/**
+\ingroup variables
Learn the szip settings of a variable.
-Similar to nc_inq_var_deflate.
-This function returns the szip settings for a variable.
-With the introduction of general filter support,
-szip inquiry is converted to use the filter interface.
+This function returns the szip settings for a variable. For more
+information on HDF5 and szip see
+https://support.hdfgroup.org/HDF5/doc/RM/RM_H5P.html#Property-SetSzip
+and https://support.hdfgroup.org/doc_resource/SZIP/index.html.
-This is a wrapper for nc_inq_var_filter().
+To if a variable is not using szip, then a zero will be passed back
+for both options_maskp and pixels_per_blockp.
\param ncid NetCDF or group ID, from a previous call to nc_open(),
nc_create(), nc_def_grp(), or associated inquiry functions such as
@@ -677,16 +679,21 @@ nc_inq_ncid().
\param varid Variable ID
\param options_maskp The szip options mask will be copied to this
-pointer. \ref ignored_if_null.
+pointer. Note that the HDF5 layer modifies the options_mask, so this
+value will be different from the value used when setting szip
+compression. \ref ignored_if_null.
\param pixels_per_blockp The szip pixels per block will be copied
-here. \ref ignored_if_null.
+here. The HDF5 layer may change this value, so this may not match the
+value passed in when setting szip compression. \ref ignored_if_null.
\returns ::NC_NOERR No error.
\returns ::NC_EBADID Bad ncid.
\returns ::NC_ENOTNC4 Not a netCDF-4 file.
\returns ::NC_ENOTVAR Invalid variable ID.
\returns ::NC_EFILTER Variable is not szip encoded
+
+\author Ed Hartnett, Dennis Heimbigner
*/
int
nc_inq_var_szip(int ncid, int varid, int *options_maskp, int *pixels_per_blockp)
