netcdf-c/plugins/H5Znoop.c
Dennis Heimbigner 44d0dcaad2 Add support for multiple filters per variable.
re: https://github.com/Unidata/netcdf-c/issues/1584

Support has been added for multiple filters per variable.  This
affects a number of components in netcdf. The new APIs are
documented in NUG/filters.md.

The primary changes are:
* A set of new functions are provided (see __include/netcdf_filter.h__).
    - Obtain a list of the filters associated with a variable
    - Obtain the parameters for a specific filter.
* The existing __nc_inq_var_filter__ function now returns info
  about the first defined filter.
* The utilities (ncgen, ncdump, and nccopy) now support
  an extended format for specifying a sequence of filters.
  The general form is __<filter>|<filter>..._.
* The ncdump **_Filter** attribute now dumps a list of all the
  filters associated with a variable using the above new format.
* Filter specifications can now use a filter name instead of number
  for filters known to the netcdf library, which in turn is taken
  from the HDF5 filter registration page.
* New errors are defined: NC_EFILTER and NC_ENOFILTER. The latter
  is returned if an attempt is made to access an unknown filter.
* Internally, the dispatch table has been extended to add a function
  to handle all of the filter functions.
* New, filter-related, tests were added to nc_test4.
* A new plugin was added to the plugins directory to help with testing.

Notes:
1. The shuffle and fletcher32 filters are not part of the multifilter system.

Misc. changes:
1. A debug module was added to libhdf5 to help catch error locations.
2020-02-16 12:59:33 -07:00

118 lines
2.9 KiB
C

#include "config.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <stdio.h>
#include <sys/types.h>
#include <hdf5.h>
/* Older versions of the hdf library may define H5PL_type_t here */
#include <H5PLextern.h>
#include "h5noop.h"
#ifndef DLL_EXPORT
#define DLL_EXPORT
#endif
/* WARNING:
Starting with HDF5 version 1.10.x, the plugin code MUST be
careful when using the standard *malloc()*, *realloc()*, and
*free()* function.
In the event that the code is allocating, reallocating, for
free'ing memory that either came from or will be exported to the
calling HDF5 library, then one MUST use the corresponding HDF5
functions *H5allocate_memory()*, *H5resize_memory()*,
*H5free_memory()* [5] to avoid memory failures.
Additionally, if your filter code leaks memory, then the HDF5 library
will generate an error.
*/
#undef DEBUG
extern void NC_filterfix8(void* mem, int decode);
const H5Z_class2_t H5Z_NOOP[1] = {{
H5Z_CLASS_T_VERS, /* H5Z_class_t version */
(H5Z_filter_t)(H5Z_FILTER_NOOP), /* Filter id number */
1, /* encoder_present flag (set to true) */
1, /* decoder_present flag (set to true) */
"noop", /* Filter name for debugging */
(H5Z_can_apply_func_t)H5Z_noop_can_apply, /* The "can apply" callback */
NULL, /* The "set local" callback */
(H5Z_func_t)H5Z_filter_noop, /* The actual filter function */
}};
/* External Discovery Functions */
H5PL_type_t
H5PLget_plugin_type(void)
{
return H5PL_TYPE_FILTER;
}
const void*
H5PLget_plugin_info(void)
{
return H5Z_NOOP;
}
/* Make this explicit */
/*
* The "can_apply" callback returns positive a valid combination, zero for an
* invalid combination and negative for an error.
*/
htri_t
H5Z_noop_can_apply(hid_t dcpl_id, hid_t type_id, hid_t space_id)
{
return 1; /* Assume it can always apply */
}
size_t
H5Z_filter_noop(unsigned int flags, size_t cd_nelmts,
const unsigned int cd_values[], size_t nbytes,
size_t *buf_size, void **buf)
{
void* newbuf;
if (flags & H5Z_FLAG_REVERSE) {
/* Replace buffer */
#ifdef HAVE_H5ALLOCATE_MEMORY
newbuf = H5allocate_memory(*buf_size,0);
#else
newbuf = malloc(*buf_size);
#endif
if(newbuf == NULL) abort();
memcpy(newbuf,*buf,*buf_size);
/* reclaim old buffer */
#ifdef HAVE_H5FREE_MEMORY
H5free_memory(*buf);
#else
free(*buf);
#endif
*buf = newbuf;
} else {
/* Replace buffer */
#ifdef HAVE_H5ALLOCATE_MEMORY
newbuf = H5allocate_memory(*buf_size,0);
#else
newbuf = malloc(*buf_size);
#endif
if(newbuf == NULL) abort();
memcpy(newbuf,*buf,*buf_size);
/* reclaim old buffer */
#ifdef HAVE_H5FREE_MEMORY
H5free_memory(*buf);
#else
free(*buf);
#endif
*buf = newbuf;
}
return *buf_size;
}