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Allow for negative clevels in Zstd #165

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Allow for negative clevels in Zstd #165

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50f43cb
Revert "Remove casting for negative clevel with Zstd"
mkitti Mar 4, 2022
800b85b
Modify Zstd plugin to accept negative values
mkitti Mar 4, 2022
ab6e7a0
Merge branch 'main' into zstd_minclevel
mkitti May 18, 2022
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4 changes: 2 additions & 2 deletions src/HDF5Plugin-Zstandard/zstd_h5plugin.c
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Original file line number Diff line number Diff line change
Expand Up @@ -35,8 +35,8 @@ DLL_EXPORT size_t zstd_filter(unsigned int flags, size_t cd_nelmts,
aggression = (int)cd_values[0];
else
aggression = ZSTD_CLEVEL_DEFAULT;
if (aggression < 1 /*ZSTD_minCLevel()*/)
aggression = 1 /*ZSTD_minCLevel()*/;
if (aggression < ZSTD_minCLevel())
aggression = ZSTD_minCLevel();
else if (aggression > ZSTD_maxCLevel())
aggression = ZSTD_maxCLevel();

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12 changes: 7 additions & 5 deletions src/hdf5plugin/__init__.py
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Expand Up @@ -391,7 +391,7 @@ class Zstd(_FilterRefClass):
**hdf5plugin.Zstd())
f.close()

:param int clevel: Compression level from 1 (lowest compression) to 22 (maximum compression).
:param int clevel: Compression level from -131072 (lowest compression) to 22 (maximum compression).
Ultra compression extends from 20 through 22. Default: 3.

.. code-block:: python
Expand All @@ -405,11 +405,13 @@ class Zstd(_FilterRefClass):
"""
filter_id = ZSTD_ID

def __init__(self, clevel=3):
assert 1 <= clevel <= 22
self.filter_options = (clevel,)

def __init__(self, clevel=None):
if clevel is not None:
# filter_options are passed as uints: conversion needed to pass negative clevel
clevel = _ctypes.c_uint(clevel).value
self.filter_options = (clevel,)


def _init_filters():
"""Initialise and register HDF5 filters with h5py

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