/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by The HDF Group. *
* 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 COPYING file, which can be found at the root of the source code *
* distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases. *
* If you do not have access to either file, you may request a copy from *
* help@hdfgroup.org. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* This file contains public declarations for the H5Z (data filter) developer
* support routines.
*/
#ifndef _H5Zdevelop_H
#define _H5Zdevelop_H
/* Include package's public header */
#include "H5Zpublic.h"
/*****************/
/* Public Macros */
/*****************/
/**
* Current version of the H5Z_class_t struct
*/
#define H5Z_CLASS_T_VERS (1)
/*******************/
/* Public Typedefs */
/*******************/
/**
* Structure for filter callback property
*/
typedef struct H5Z_cb_t {
H5Z_filter_func_t func;
void * op_data;
} H5Z_cb_t;
/**
* \brief This callback determines if a filter can be applied to the dataset
* with the characteristics provided
*
* \dcpl_id
* \type_id
* \space_id
*
* \return \htri_t
*
* \details Before a dataset gets created, the \ref H5Z_can_apply_func_t
* callbacks for any filters used in the dataset creation property list
* are called with the dataset's dataset creation property list, the
* dataset's datatype and a dataspace describing a chunk (for chunked
* dataset storage).
*
* The \ref H5Z_can_apply_func_t callback must determine if the
* combination of the dataset creation property list setting, the
* datatype and the dataspace represent a valid combination to apply
* this filter to. For example, some cases of invalid combinations may
* involve the filter not operating correctly on certain datatypes (or
* certain datatype sizes), or certain sizes of the chunk dataspace.
*
* The \ref H5Z_can_apply_func_t callback can be the NULL pointer, in
* which case, the library will assume that it can apply to any
* combination of dataset creation property list values, datatypes and
* dataspaces.
*
* The \ref H5Z_can_apply_func_t callback returns positive a valid
* combination, zero for an invalid combination and negative for an
* error.
*/
//! <!-- [H5Z_can_apply_func_t_snip] -->
typedef htri_t (*H5Z_can_apply_func_t)(hid_t dcpl_id, hid_t type_id, hid_t space_id);
//! <!-- [H5Z_can_apply_func_t_snip] -->
/**
* \brief The filter operation callback function, defining a filter's operation
* on data
*
* \dcpl_id
* \type_id
* \space_id
*
* \return \herr_t
*
* \details After the \ref H5Z_can_apply_func_t callbacks are checked for new
* datasets, the \ref H5Z_set_local_func_t callbacks for any filters
* used in the dataset creation property list are called. These
* callbacks receive the dataset's private copy of the dataset creation
* property list passed in to H5Dcreate() (i.e. not the actual property
* list passed in to H5Dcreate()) and the datatype ID passed in to
* H5Dcreate() (which is not copied and should not be modified) and a
* dataspace describing the chunk (for chunked dataset storage) (which
* should also not be modified).
*
* The \ref H5Z_set_local_func_t callback must set any parameters that
* are specific to this dataset, based on the combination of the
* dataset creation property list values, the datatype and the
* dataspace. For example, some filters perform different actions based
* on different datatypes (or datatype sizes) or different number of
* dimensions or dataspace sizes.
*
* The \ref H5Z_set_local_func_t callback can be the NULL pointer, in
* which case, the library will assume that there are no
* dataset-specific settings for this filter.
*
* The \ref H5Z_set_local_func_t callback must return non-negative on
* success and negative for an error.
*/
//! <!-- [H5Z_set_local_func_t_snip] -->
typedef herr_t (*H5Z_set_local_func_t)(hid_t dcpl_id, hid_t type_id, hid_t space_id);
//! <!-- [H5Z_set_local_func_t_snip] -->
/**
* \brief The filter operation callback function, defining a filter's operation
* on data
*
* \param[in] flags Bit vector specifying certain general properties of the filter
* \param[in] cd_nelmts Number of elements in \p cd_values
* \param[in] cd_values Auxiliary data for the filter
* \param[in] nbytes The number of valid bytes in \p buf to be filtered
* \param[in,out] buf_size The size of \p buf
* \param[in,out] buf The filter buffer
*
* \return Returns the number of valid bytes of data contained in \p buf. In the
* case of failure, the return value is 0 (zero) and all pointer
* arguments are left unchanged.
*
* \details A filter gets definition flags and invocation flags (defined
* above), the client data array and size defined when the filter was
* added to the pipeline, the size in bytes of the data on which to
* operate, and pointers to a buffer and its allocated size.
*
* The filter should store the result in the supplied buffer if
* possible, otherwise it can allocate a new buffer, freeing the
* original. The allocated size of the new buffer should be returned
* through the \p buf_size pointer and the new buffer through the \p
* buf pointer.
*
* The return value from the filter is the number of bytes in the
* output buffer. If an error occurs then the function should return
* zero and leave all pointer arguments unchanged.
*/
//! <!-- [H5Z_func_t_snip] -->
typedef size_t (*H5Z_func_t)(unsigned int flags, size_t cd_nelmts, const unsigned int cd_values[],
size_t nbytes, size_t *buf_size, void **buf);
//! <!-- [H5Z_func_t_snip] -->
/**
* The filter table maps filter identification numbers to structs that
* contain a pointers to the filter function and timing statistics.
*/
//! <!-- [H5Z_class2_t_snip] -->
typedef struct H5Z_class2_t {
int version; /**< Version number of the H5Z_class_t struct */
H5Z_filter_t id; /**< Filter ID number */
unsigned encoder_present; /**< Does this filter have an encoder? */
unsigned decoder_present; /**< Does this filter have a decoder? */
const char * name; /**< Comment for debugging */
H5Z_can_apply_func_t can_apply; /**< The "can apply" callback for a filter */
H5Z_set_local_func_t set_local; /**< The "set local" callback for a filter */
H5Z_func_t filter; /**< The actual filter function */
} H5Z_class2_t;
//! <!-- [H5Z_class2_t_snip] -->
/********************/
/* Public Variables */
/********************/
/*********************/
/* Public Prototypes */
/*********************/
#ifdef __cplusplus
extern "C" {
#endif
/**
* \ingroup H5Z
*
* \brief Registers a new filter with the HDF5 library
*
* \param[in] cls A pointer to a buffer for the struct containing the
* filter-definition
*
* \return \herr_t
*
* \details H5Zregister() registers a new filter with the HDF5 library.
*
* \details Making a new filter available to an application is a two-step
* process. The first step is to write the three filter callback
* functions described below: \c can_apply, \c set_local, and \c
* filter. This call to H5Zregister(), registering the filter with the
* library, is the second step. The can_apply and set_local fields can
* be set to NULL if they are not required for the filter being
* registered.
*
* H5Zregister() accepts a single parameter, a pointer to a buffer for
* the \p cls data structure. That data structure must conform to one
* of the following definitions:
* \snippet this H5Z_class1_t_snip
* or
* \snippet this H5Z_class2_t_snip
*
* \c version is a library-defined value reporting the version number
* of the #H5Z_class_t struct. This currently must be set to
* #H5Z_CLASS_T_VERS.
*
* \c id is the identifier for the new filter. This is a user-defined
* value between #H5Z_FILTER_RESERVED and #H5Z_FILTER_MAX. These
* values are defined in the HDF5 source file H5Zpublic.h, but the
* symbols #H5Z_FILTER_RESERVED and #H5Z_FILTER_MAX should always be
* used instead of the literal values.
*
* \c encoder_present is a library-defined value indicating whether
* the filter’s encoding capability is available to the application.
*
* \c decoder_present is a library-defined value indicating whether
* the filter’s encoding capability is available to the application.
*
* \c name is a descriptive comment used for debugging, may contain a
* descriptive name for the filter, and may be the null pointer.
*
* \c can_apply, described in detail below, is a user-defined callback
* function which determines whether the combination of the dataset
* creation property list values, the datatype, and the dataspace
* represent a valid combination to apply this filter to.
*
* \c set_local, described in detail below, is a user-defined callback
* function which sets any parameters that are specific to this
* dataset, based on the combination of the dataset creation property
* list values, the datatype, and the dataspace.
*
* \c filter, described in detail below, is a user-defined callback
* function which performs the action of the filter.
*
* The statistics associated with a filter are not reset by this
* function; they accumulate over the life of the library.
*
* #H5Z_class_t is a macro which maps to either H5Z_class1_t or
* H5Z_class2_t, depending on the needs of the application. To affect
* only this macro, H5Z_class_t_vers may be defined to either 1 or 2.
* Otherwise, it will behave in the same manner as other API
* compatibility macros. See API Compatibility Macros in HDF5 for more
* information. H5Z_class1_t matches the #H5Z_class_t structure that is
* used in the 1.6.x versions of the HDF5 library.
*
* H5Zregister() will automatically detect which structure type has
* been passed in, regardless of the mapping of the #H5Z_class_t macro.
* However, the application must make sure that the fields are filled
* in according to the correct structure definition if the macro is
* used to declare the structure.
*
* \Bold{The callback functions:}\n Before H5Zregister() can link a
* filter into an application, three callback functions must be
* defined as described in the HDF5 library header file H5Zpublic.h.
*
* When a filter is applied to the fractal heap for a group (e.g.,
* when compressing group metadata) and if the can apply and set local
* callback functions have been defined for that filter, HDF5 passes
* the value -1 for all parameters for those callback functions. This
* is done to ensure that the filter will not be applied to groups if
* it relies on these parameters, as they are not applicable to group
* fractal heaps; to operate on group fractal heaps, a filter must be
* capable of operating on an opaque block of binary data.
*
* The \Emph{can apply} callback function must return a positive value
* for a valid combination, zero for an invalid combination, and a
* negative value for an error.
* \snippet this H5Z_can_apply_func_t_snip
*
* Before a dataset is created, the \Emph{can apply} callbacks for any
* filters used in the dataset creation property list are called with
* the dataset's dataset creation property list, \c dcpl_id, the
* dataset's datatype, \p type_id, and a dataspace describing a chunk,
* \p space_id, (for chunked dataset storage).
*
* This callback must determine whether the combination of the dataset
* creation property list settings, the datatype, and the dataspace
* represent a valid combination to which to apply this filter. For
* example, an invalid combination may involve the filter not
* operating correctly on certain datatypes, on certain datatype
* sizes, or on certain sizes of the chunk dataspace. If this filter
* is enabled through H5Pset_filter() as optional and the can apply
* function returns 0, the library will skip the filter in the filter
* pipeline.
*
* This callback can be the NULL pointer, in which case the library
* will assume that the filter can be applied to a dataset with any
* combination of dataset creation property list values, datatypes,
* and dataspaces.
*
* The \Emph{set local} callback function is defined as follows:
* \snippet this H5Z_set_local_func_t_snip
*
* After the can apply callbacks are checked for a new dataset, the
* \Emph{set local} callback functions for any filters used in the
* dataset creation property list are called. These callbacks receive
* \c dcpl_id, the dataset's private copy of the dataset creation
* property list passed in to H5Dcreate() (i.e. not the actual
* property list passed in to H5Dcreate()); \c type_id, the datatype
* identifier passed in to H5Dcreate(), which is not copied and should
* not be modified; and \c space_id, a dataspace describing the chunk
* (for chunked dataset storage), which should also not be modified.
*
* The set local callback must set any filter parameters that are
* specific to this dataset, based on the combination of the dataset
* creation property list values, the datatype, and the dataspace. For
* example, some filters perform different actions based on different
* datatypes, datatype sizes, numbers of dimensions, or dataspace
* sizes.
*
* The \Emph{set local} callback may be the NULL pointer, in which
* case, the library will assume that there are no dataset-specific
* settings for this filter.
*
* The \Emph{set local} callback function must return a non-negative
* value on success and a negative value for an error.
*
* The \Emph{filter operation} callback function, defining the
* filter's operation on the data, is defined as follows:
* \snippet this H5Z_func_t_snip
*
* The parameters \c flags, \c cd_nelmts, and \c cd_values are the
* same as for the function H5Pset_filter(). The one exception is that
* an additional flag, #H5Z_FLAG_REVERSE, is set when the filter is
* called as part of the input pipeline.
*
* The parameter \c buf points to the input buffer which has a size of
* \c buf_size bytes, \c nbytes of which are valid data.
*
* The filter should perform the transformation in place if possible.
* If the transformation cannot be done in place, then the filter
* should allocate a new buffer with malloc() and assign it to \c buf,
* assigning the allocated size of that buffer to \c buf_size. The old
* buffer should be freed by calling free().
*
* If successful, the \Emph{filter operation} callback function
* returns the number of valid bytes of data contained in \c buf. In
* the case of failure, the return value is 0 (zero) and all pointer
* arguments are left unchanged.
*
* \version 1.8.6 Return type for the \Emph{can apply} callback function,
* \ref H5Z_can_apply_func_t, changed to \ref htri_t.
* \version 1.8.5 Semantics of the \Emph{can apply} and \Emph{set local}
* callback functions changed to accommodate the use of filters
* with group fractal heaps.
* \version 1.8.3 #H5Z_class_t renamed to H5Z_class2_t, H5Z_class1_t structure
* introduced for backwards compatibility with release 1.6.x,
* and #H5Z_class_t macro introduced in this release. Function
* modified to accept either structure type.
* \version 1.8.0 The fields \c version, \c encoder_present, and
* \c decoder_present were added to the #H5Z_class_t \c struct
* in this release.
* \version 1.6.0 This function was substantially revised in Release 1.6.0 with
* a new #H5Z_class_t struct and new set local and can apply
* callback functions.
*
*/
H5_DLL herr_t H5Zregister(const void *cls);
/**
* \ingroup H5Z
*
* \brief Unregisters a filter.
*
* \param[in] id Identifier of the filter to be unregistered.
* \return \herr_t
*
* \details H5Zunregister() unregisters the filter specified in \p id.
*
* \details This function first iterates through all opened datasets and
* groups. If an open object that uses this filter is found, the
* function will fail with a message indicating that an object using
* the filter is still open. All open files are then flushed to make
* sure that all cached data that may use this filter are written out.
*
* If the application is a parallel program, all processes that
* participate in collective data write should call this function to
* ensure that all data is flushed.
*
* After a call to H5Zunregister(), the filter specified in filter
* will no longer be available to the application.
*
* \version 1.8.12 Function modified to check for open objects using the
* filter.
* \since 1.6.0
*/
H5_DLL herr_t H5Zunregister(H5Z_filter_t id);
#ifdef __cplusplus
}
#endif
/* Symbols defined for compatibility with previous versions of the HDF5 API.
*
* Use of these symbols is deprecated.
*/
#ifndef H5_NO_DEPRECATED_SYMBOLS
/**
* The filter table maps filter identification numbers to structs that
* contain a pointers to the filter function and timing statistics.
*/
//! <!-- [H5Z_class1_t_snip] -->
typedef struct H5Z_class1_t {
H5Z_filter_t id; /**< Filter ID number */
const char * name; /**< Comment for debugging */
H5Z_can_apply_func_t can_apply; /**< The "can apply" callback for a filter */
H5Z_set_local_func_t set_local; /**< The "set local" callback for a filter */
H5Z_func_t filter; /**< The actual filter function */
} H5Z_class1_t;
//! <!-- [H5Z_class1_t_snip] -->
#endif /* H5_NO_DEPRECATED_SYMBOLS */
#endif /* _H5Zdevelop_H */