dfilter.c File Reference

Functions for working with filters. More...

#include "config.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "netcdf.h"
#include "netcdf_filter.h"
#include "ncdispatch.h"
#include "nc4internal.h"
#include "nclog.h"

Go to the source code of this file.

Functions
int	nc_def_var_blosc (int ncid, int varid, unsigned subcompressor, unsigned level, unsigned blocksize, unsigned addshuffle)
	Turn on blosc for a variable.
int	nc_def_var_bzip2 (int ncid, int varid, int level)
	Turn on bzip2 compression for a variable.
EXTERNL int	nc_def_var_filter (int ncid, int varid, unsigned int id, size_t nparams, const unsigned int *params)
	Define a new variable filter Assumes HDF5 format using unsigned ints.
int	nc_def_var_zstandard (int ncid, int varid, int level)
	Turn on Zstandard compression for a variable.
EXTERNL int	nc_inq_filter_avail (int ncid, unsigned id)
	Test if filter is available.
int	nc_inq_var_blosc (int ncid, int varid, int *hasfilterp, unsigned *subcompressorp, unsigned *levelp, unsigned *blocksizep, unsigned *addshufflep)
	Learn whether Blosc compression is on for a variable, and, if so, the settings.
int	nc_inq_var_bzip2 (int ncid, int varid, int *hasfilterp, int *levelp)
	Learn whether bzip2 compression is on for a variable, and, if so, the level setting.
EXTERNL int	nc_inq_var_filter (int ncid, int varid, unsigned int *idp, size_t *nparamsp, unsigned int *params)
	Find the first filter (if any) associated with a variable.
EXTERNL int	nc_inq_var_filter_ids (int ncid, int varid, size_t *nfiltersp, unsigned int *ids)
	Find the set of filters (if any) associated with a variable.
EXTERNL int	nc_inq_var_filter_info (int ncid, int varid, unsigned int id, size_t *nparamsp, unsigned int *params)
	Find the the param info about filter (if any) associated with a variable and with specified id.
int	nc_inq_var_zstandard (int ncid, int varid, int *hasfilterp, int *levelp)
	Learn whether Zstandard compression is on for a variable, and, if so, the level setting.

Detailed Description

Functions for working with filters.

Definition in file dfilter.c.

Function Documentation

nc_def_var_bzip2()

int nc_def_var_bzip2	(	int	ncid,
		int	varid,
		int	level
	)

Turn on bzip2 compression for a variable.

Parameters

ncid	File ID.
varid	Variable ID.
level	From 1 to 9. Set the block size to 100k, 200k ... 900k when compressing. (bzip2 default level is 9).

Returns

0 for success, error code otherwise.

Author

Dennis Heimbigner, Ed Hartnett

Definition at line 236 of file dfilter.c.

nc_def_var_filter()

EXTERNL int nc_def_var_filter	(	int	ncid,
		int	varid,
		unsigned int	id,
		size_t	nparams,
		const unsigned int *	params
	)

Define a new variable filter Assumes HDF5 format using unsigned ints.

Only variables with chunked storage can use filters.

Parameters

ncid	File and group ID.
varid	Variable ID.
id	Filter ID.
nparams	Number of filter parameters.
params	Filter parameters.

Returns

NC_NOERR No error.

NC_EINVAL Variable must be chunked.

NC_EBADID Bad ID.

Author

Dennis Heimbigner

Definition at line 126 of file dfilter.c.

nc_def_var_zstandard()

int nc_def_var_zstandard	(	int	ncid,
		int	varid,
		int	level
	)

Turn on Zstandard compression for a variable.

Parameters

ncid	File ID.
varid	Variable ID.
level	From -131072 to 22 (depends on Zstandard version). when compressing. Regular compression levels are from 1 up to 19. Use levels >= 20, labeled --ultra, cautiously: they require more memory. Negative compression levels that extend the range of speed vs. ratio preferences. The lower the level, the faster the speed (at the cost of compression).

Returns

0 for success, error code otherwise.

Author

Charlie Zender, Dennis Heimbigner, Ed Hartnett

Definition at line 304 of file dfilter.c.

nc_inq_filter_avail()

EXTERNL int nc_inq_filter_avail	(	int	ncid,
		unsigned	id
	)

Test if filter is available.

Would prefer returning a list of all available filters, but HDF5 does not support that capability.

Parameters

ncid	ID of file for which filter list is desired
id	filter id of interest

Returns

NC_NOERR if the filter is available

NC_EBADID if ncid is invalid

NC_ENOFILTER if filter is not available.

Author

Dennis Heimbigner

Definition at line 209 of file dfilter.c.

nc_inq_var_blosc()

int nc_inq_var_blosc	(	int	ncid,
		int	varid,
		int *	hasfilterp,
		unsigned *	subcompressorp,
		unsigned *	levelp,
		unsigned *	blocksizep,
		unsigned *	addshufflep
	)

Learn whether Blosc compression is on for a variable, and, if so, the settings.

Parameters

ncid	File ID.
varid	Variable ID.
hasfilterp	Pointer that gets a 0 if blosc is not in use for this var, and a 1 if it is. Ignored if NULL.
subcompressorp	Pointer that gets the subcompressor, if blosc is in use. Ignored if NULL.
levelp	Pointer that gets the level setting, if blosc is in use. Ignored if NULL.
blocksizep	Pointer that gets the block size, if blosc is in use. Ignored if NULL.
addshufflep	Pointer that gets non-zero value if shuffle is in use, if blosc is in use. Ignored if NULL.

Returns

0 for success, error code otherwise.

Author

Dennis Heimbigner

Definition at line 431 of file dfilter.c.

nc_inq_var_bzip2()

int nc_inq_var_bzip2	(	int	ncid,
		int	varid,
		int *	hasfilterp,
		int *	levelp
	)

Learn whether bzip2 compression is on for a variable, and, if so, the level setting.

Parameters

ncid	File ID.
varid	Variable ID.
hasfilterp	Pointer that gets a 0 if bzip2 is not in use for this var, and a 1 if it is. Ignored if NULL.
levelp	Pointer that gets the level setting (from 1 to 9), if bzip2 is in use. Ignored if NULL.

Returns

0 for success, error code otherwise.

Author

Dennis Heimbigner, Ed Hartnett

Definition at line 267 of file dfilter.c.

nc_inq_var_zstandard()

int nc_inq_var_zstandard	(	int	ncid,
		int	varid,
		int *	hasfilterp,
		int *	levelp
	)

Learn whether Zstandard compression is on for a variable, and, if so, the level setting.

Parameters

ncid	File ID.
varid	Variable ID.
hasfilterp	Pointer that gets a 0 if Zstandard is not in use for this var, and a 1 if it is. Ignored if NULL.
levelp	Pointer that gets the level setting (from -131072 to 22), if Zstandard is in use. Ignored if NULL.

Returns

0 for success, error code otherwise.

Author

Charlie Zender, Dennis Heimbigner, Ed Hartnett

Definition at line 340 of file dfilter.c.