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"""
Python bindings for libvbz
"""
__version__ = "0.9.3"
import numpy as np
from _vbz import lib, ffi
def compression_options(zigzag, size, zlevel=1, version=0):
options = ffi.new("CompressionOptions *")
options.integer_size = size
options.perform_delta_zig_zag = zigzag
options.zstd_compression_level = zlevel
options.vbz_version = version
return options
def compress(data, options=None):
if options is None:
zigzag = np.issubdtype(data.dtype, np.signedinteger)
options = compression_options(zigzag, data.dtype.itemsize)
output_size = lib.vbz_max_compressed_size(len(data) * options.integer_size, options)
output = np.empty(output_size, dtype=np.uint8)
if lib.vbz_is_error(output_size):
raise Exception("Something unexpected went wrong")
size = lib.vbz_compress_sized(
ffi.cast("void const *", ffi.from_buffer(data)),
len(data) * options.integer_size,
ffi.cast("void *", ffi.from_buffer(output)),
output_size,
options
)
if lib.vbz_is_error(size):
raise Exception("Something unexpected went wrong")
return output[:size]
def decompress(data, dtype, options=None):
if options is None:
zigzag = np.issubdtype(dtype, np.signedinteger)
try:
options = compression_options(zigzag, dtype.itemsize)
except TypeError:
options = compression_options(zigzag, dtype().itemsize)
uncompressed_size = lib.vbz_decompressed_size(
ffi.cast("void const *", ffi.from_buffer(data)),
len(data),
options
)
if lib.vbz_is_error(uncompressed_size):
raise Exception("Something unexpected went wrong")
output = np.empty(uncompressed_size, dtype=dtype)
size = lib.vbz_decompress_sized(
ffi.cast("void const *", ffi.from_buffer(data)),
len(data),
ffi.cast("void *", ffi.from_buffer(output)),
uncompressed_size,
options
)
if lib.vbz_is_error(size):
raise Exception("Something unexpected went wrong")
return output[:int(size / options.integer_size)]
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