NAME

compression_tool — encode/decode files using the Compression library.

SYNOPSIS

DESCRIPTION

compression_tool encodes (compresses), or decodes (uncompresses) files using the Compression library.

OPTIONS

-encode

Encode (compress) the input

-decode

Decode (uncompress) the input

--a algorithm

Set the compression algorithm, valid options are zlib, lzma, lzfse, lz4, lz4_raw. Default is lzfse.
- zlib      raw DEFLATE payload, as defined in IETF RFC 1951, encoder is zlib level 5,
- lzma      LZMA2 payload inside a XZ container, encoder is LZMA2 preset 6,
- lz4       raw LZ4 payload inside a simple frame format (described in compression.h),
- lz4_raw   raw LZ4 payload,
- lzfse     LZFSE payload.

--A algorithm

Enable block compression, and set compression algorithm, valid options are zlib, lzma, lzfse, lz4. Default is lzfse.

--b block_size

Set block size for block compression. The integer value can be followed by m or k or b.

--t thread_count

Set the number of worker threads to use for block compression/decompression. Default is the number of logical threads on the machine.

--i input_file

Input file. If omitted, read from standard input.

--o output_file

Output file. If omitted, write to standard output.

--v

Increase verbosity. Default is silent operation.

--h

Print usage and exit.

BLOCK COMPRESSION FILE FORMAT

The file starts with a 4-byte header 'p','b','z',<algo>, where <algo> indicates the algorithm used to compress data. The header is followed by the 64-bit block size in bytes. Then for each block, we have 64-bit uncompressed size (will batch the block size, except possibly for the last block), 64-bit compressed size, and the compressed payload. If both uncompressed and compressed sizes for a block are equal, the payload is stored uncompressed. All 64-bit values are stored big-endian. Valid values for <algo> are: 'z' for zlib, 'x' for lzma, '4' for lz4, and 'e' for lzfse.