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Filter support has three goals: 1. Use the existing HDF5 filter implementations, 2. Allow filter metadata to be stored in the NumCodecs metadata format used by Zarr, 3. Allow filters to be used even when HDF5 is disabled Detailed usage directions are define in docs/filters.md. For now, the existing filter API is left in place. So filters are defined using ''nc_def_var_filter'' using the HDF5 style where the id and parameters are unsigned integers. This is a big change since filters affect many parts of the code. In the following, the terms "compressor" and "filter" and "codec" are generally used synonomously. ### Filter-Related Changes: * In order to support dynamic loading of shared filter libraries, a new library was added in the libncpoco directory; it helps to isolate dynamic loading across multiple platforms. * Provide a json parsing library for use by plugins; this is created by merging libdispatch/ncjson.c with include/ncjson.h. * Add a new _Codecs attribute to allow clients to see what codecs are being used; let ncdump -s print it out. * Provide special headers to help support compilation of HDF5 filters when HDF5 is not enabled: netcdf_filter_hdf5_build.h and netcdf_filter_build.h. * Add a number of new test to test the new nczarr filters. * Let ncgen parse _Codecs attribute, although it is ignored. ### Plugin directory changes: * Add support for the Blosc compressor; this is essential because it is the most common compressor used in Zarr datasets. This also necessitated adding a CMake FindBlosc.cmake file * Add NCZarr support for the big-four filters provided by HDF5: shuffle, fletcher32, deflate (zlib), and szip * Add a Codec defaulter (see docs/filters.md) for the big four filters. * Make plugins work with windows by properly adding __declspec declaration. ### Misc. Non-Filter Changes * Replace most uses of USE_NETCDF4 (deprecated) with USE_HDF5. * Improve support for caching * More fixes for path conversion code * Fix misc. memory leaks * Add new utility -- ncdump/ncpathcvt -- that does more or less the same thing as cygpath. * Add a number of new test to test the non-filter fixes. * Update the parsers * Convert most instances of '#ifdef _MSC_VER' to '#ifdef _WIN32'
53 lines
1.9 KiB
C
53 lines
1.9 KiB
C
/* Copyright 2018-2018 University Corporation for Atmospheric
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Research/Unidata. */
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/**
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* @file This header file containsfilter related macros, types, and prototypes for
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* the filter code in libnczarr. This header should not be included in
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* code outside libnczarr.
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*
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* @author Dennis Heimbigner
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*/
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#ifndef ZFILTER_H
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#define ZFILTER_H
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/* zfilter.c */
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/* Dispatch functions are also in zfilter.c */
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/* Filterlist management */
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/*Mnemonic*/
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#define ENCODING 1
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/* list of environment variables to check for plugin roots */
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#define plugin_env "HDF5_PLUGIN_PATH"
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#define plugin_dir_unix "/usr/local/hdf5/plugin"
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#define plugin_dir_win "%s/hdf5/lib/plugin"
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#define win32_root_env "ALLUSERSPROFILE"
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/*
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Return a NULL terminated vector of pointers to instances of ''NCZ_codec_t''.
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The value returned is actually of type ''NCZ_codec_t**'',
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but is of type ''void*'' to allow for extensions.
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The list of returned items are used to try to provide defaults
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for any HDF5 filters that have no corresponding Codec.
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This is for internal use only.
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*/
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typedef void* (*NCZ_codec_info_defaults_proto)(void);
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/* Opaque */
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struct NCZ_Filter;
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int NCZ_filter_initialize(void);
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int NCZ_filter_finalize(void);
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int NCZ_addfilter(NC_FILE_INFO_T*, NC_VAR_INFO_T* var, unsigned int id, size_t nparams, const unsigned int* params);
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int NCZ_filter_setup(NC_VAR_INFO_T* var);
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int NCZ_filter_freelist(NC_VAR_INFO_T* var);
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int NCZ_codec_freelist(NCZ_VAR_INFO_T* zvar);
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int NCZ_applyfilterchain(const NC_FILE_INFO_T*, NC_VAR_INFO_T*, NClist* chain, size_t insize, void* indata, size_t* outlen, void** outdata, int encode);
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int NCZ_filter_jsonize(const NC_FILE_INFO_T*, const NC_VAR_INFO_T*, struct NCZ_Filter* filter, struct NCjson**);
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int NCZ_filter_build(const NC_FILE_INFO_T*, NC_VAR_INFO_T* var, const NCjson* jfilter);
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int NCZ_codec_attr(const NC_VAR_INFO_T* var, size_t* lenp, void* data);
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#endif /*ZFILTER_H*/
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