internal static void ExecutePipeline(List <FilterDescription> pipeline,
ExtendedFilterFlags flags,
Memory <byte> filterBuffer,
Span <byte> resultBuffer)
{
// H5Z.c (H5Z_pipeline)
/* Read */
if (flags.HasFlag(ExtendedFilterFlags.Reverse))
{
for (int i = pipeline.Count; i > 0; --i)
{
var filter = pipeline[i - 1];
var registration = H5Filter.Registrations.FirstOrDefault(current => current.Identifier == filter.Identifier);
if (registration == null)
{
var filterName = string.IsNullOrWhiteSpace(filter.Name) ? "unnamed filter" : filter.Name;
throw new Exception($"Could not find filter '{filterName}' with ID '{filter.Identifier}'. Make sure the filter has been registered using H5Filter.Register(...).");
}
var tmpFlags = (ExtendedFilterFlags)((ushort)flags | (ushort)filter.Flags);
try
{
filterBuffer = registration.FilterFunc(tmpFlags, filter.ClientData, filterBuffer);
}
catch (Exception ex)
{
throw new Exception("Filter pipeline failed.", ex);
}
}
filterBuffer
.Span[0..resultBuffer.Length]
public static unsafe Memory <byte> FilterFunc(ExtendedFilterFlags flags, uint[] parameters, Memory <byte> buffer)
{
// adapted from https://github.com/Blosc/hdf5-blosc/blob/bd8ee59708f366ac561153858735165d3a543b18/src/blosc_filter.c#L145-L272
int status = 0;
uint clevel = 5;
uint doshuffle = 1;
byte[] resultBuffer = null;
CompressorCodes compcode;
/* Filter params that are always set */
var typesize = parameters[2]; /* The datatype size */
ulong outbuf_size = parameters[3]; /* Precomputed buffer guess */
/* Optional params */
if (parameters.Length >= 5)
{
clevel = parameters[4]; /* The compression level */
}
if (parameters.Length >= 6)
{
doshuffle = parameters[5]; /* BLOSC_SHUFFLE, BLOSC_BITSHUFFLE */
}
if (parameters.Length >= 7)
{
compcode = (CompressorCodes)parameters[6]; /* The Blosc compressor used */
/* Check that we actually have support for the compressor code */
var namePtr = IntPtr.Zero;
var compressorsPtr = Blosc.blosc_list_compressors();
var code = Blosc.blosc_compcode_to_compname(compcode, ref namePtr);
if (code == -1)
{
throw new Exception($"This Blosc library does not have support for the '{Marshal.PtrToStringAnsi(namePtr)}' compressor, but only for: {Marshal.PtrToStringAnsi(compressorsPtr)}.");
}
}
/* We're decompressing */
if (flags.HasFlag(ExtendedFilterFlags.Reverse))
{
/* Extract the exact outbuf_size from the buffer header.
*
* NOTE: the guess value got from "cd_values" corresponds to the
* uncompressed chunk size but it should not be used in a general
* cases since other filters in the pipeline can modify the buffere
* size.
*/
fixed(byte *srcPtr = buffer.Span)
{
Blosc.blosc_cbuffer_sizes(new IntPtr(srcPtr), out outbuf_size, out var cbytes, out var blocksize);
resultBuffer = new byte[outbuf_size];
fixed(byte *destPtr = resultBuffer)
{
status = Blosc.blosc_decompress(new IntPtr(srcPtr), new IntPtr(destPtr), outbuf_size);
/* decompression failed */
if (status <= 0)
{
throw new Exception("Blosc decompression error.");
}
}
}
return(resultBuffer);
}
/* We're compressing */
else
{
throw new Exception("Writing data chunks is not yet supported by HDF5.NET.");
}
}
