This module allows compression and decompression of binary data with the DEFLATE algorithm (commonly used in the zlib library and gzip archiver).
Prefer to use
deflate.DeflateIO instead of the functions in this
module as it provides a streaming interface to compression and decompression
which is convenient and more memory efficient when working with reading or
writing compressed data to a file, socket, or stream.
From MicroPython v1.21 onwards, this module may not be present by default on all MicroPython firmware as it duplicates functionality available in the
Requires the built-in
deflatemodule (available since MicroPython v1.21)
Compression support will only be available if compression support is enabled in the built-in
- zlib.decompress(data, wbits=15, /)¶
Decompresses data into a bytes object.
The wbits parameter works the same way as for
zlib.compress()with the following additional valid values:
0: Automatically determine the window size from the zlib header (data must be in zlib format).
47: Auto-detect either the zlib or gzip format.
zlib.compress(), see the
CPython documentation for zlibfor more information about the wbits parameter. As for
zlib.compress(), MicroPython also supports smaller window sizes than CPython. See more MicroPython-specific details in the
If the data to be decompressed requires a larger window size, it will fail during decompression.
- zlib.compress(data, wbits=15, /)¶
Compresses data into a bytes object.
wbits allows you to configure the DEFLATE dictionary window size and the output format. The window size allows you to trade-off memory usage for compression level. A larger window size will allow the compressor to reference fragments further back in the input. The output formats are “raw” DEFLATE (no header/footer), zlib, and gzip, where the latter two include a header and checksum.
The low four bits of the absolute value of wbits set the base-2 logarithm of the DEFLATE dictionary window size. So for example,
wbits=26all set the window size to 1024 bytes. Valid window sizes are
15inclusive (corresponding to 32 to 32k bytes).
Negative values of wbits between
-15correspond to “raw” output mode, positive values between
15correspond to zlib output mode, and positive values between
31correspond to gzip output mode.
CPython documentation for zlibfor more information about the wbits parameter. Note that MicroPython allows for smaller window sizes, which is useful when memory is constrained while still achieving a reasonable level of compression. It also speeds up the compressor. See more MicroPython-specific details in the