Changes

Revision history for Compression-Util

0.16    2026-03-31

        [IMPROVEMENTS]

        - Better performance in `bwt_sort()` for certain inputs. (~2x faster)
        - Better performance in `bwt_decode()`, `huffman_decode()` and `huffman_from_freq()`.
        - Better performance in `lzss_decode()`.

0.15    2025-04-03

        [BUG-FIXES]

        - Set the appropriate DEFLATE values inside the `deflate_*` functions.

0.14    2024-11-06

        [ADDITIONS]

        - Added the `adler32()` checksum function.
        - Added the `zlib_compress()` and `zlib_uncompress()` functions.
        - Added the following low-level functions:

            deflate_create_block_type_0_header
            deflate_create_block_type_1
            deflate_create_block_type_2

            deflate_extract_next_block
            deflate_extract_block_type_0
            deflate_extract_block_type_1
            deflate_extract_block_type_2

0.13    2024-08-25

        [IMPROVEMENTS]

        - More Gzip flags are now recognized.
        - Better compression ratio in bzip2_compress().

        [BUG-FIXES]

        - Fixed the extraction of Gzip data that contains a comment.
        - Fixed a potential CRC32 issue in bzip2_compress() when data gets expanded.

0.12    2024-08-23

        [ADDITIONS]

        - Added the `lz4_compress()` and `lz4_decompress()`  functions.

        [IMPROVEMENTS]

        - Slightly better performance in `mtf_encode()`.
        - Replaced all "die" statements, with Carp::confess(), for better debugging.

        [BUG-FIXES]

        - Allow `$LZ77_MIN_LEN` to be set by the user to a value greater than 4, before calling `gzip_compress()`.

0.11    2024-08-22

        [ADDITIONS]

        - Added the `crc32()` function.
        - Added the `int2bytes()` and `int2bytes_lsb()` functions.
        - Added the `bzip2_compress()` and `bzip2_decompress()` functions.
        - Added the `gzip_compress()` and `gzip_decompress()` functions.
        - Added the `encode_alphabet_256()` and `decode_alphabet_256()` functions.

        [IMPROVEMENTS]

        - Minor documentation improvements.
        - Slightly more efficient encoding of the alphabet, in function `encode_alphabet()`.

        [CHANGES]

        - Changed the default value of `$Compression::Util::LZ_MAX_LEN` from 258 to 32768. For some inputs, this results in better compression at no additional costs.

0.10    2024-08-07

        [ADDITIONS]

        - Added the `mrl_compress()` and `mrl_decompress()` functions, for compressing/decompressing strings.
        - Added the `bytes2int()` and `bytes2int_lsb()` functions.

        [CHANGES]

        - Changed the order of values returned by `lz77_encode()`.
        - Changed the order of arguments accepted by `lz77_decode()`.

        [FIXES]

        - Fixed an issue in `lzb_decompress($fh)`, when there is more data after the LZB block.

0.09    2024-06-26

        - Generalized `make_deflate_tables()` to generate tables for arbitrarily large distances and match lengths.
        - Generalized `deflate_encode()` to encode arbitrarily large distances and arbitrarily large match lengths.
        - Better compression ratio when `$LZ_MAX_DIST` is set to a small value.
        - Minor documentation and performance improvements.

0.08    2024-06-03

        [ADDITIONS]

        - Added the `lzb_compress()` and `lzb_decompress()` functions.
        - Added the `lzss_encode_symbolic()` and `lzss_decode_symbolic()` functions.
        - Added the `lzss_compress_symbolic()` and `lzss_decompress_symbolic()` functions.
        - Added the `$LZ_MAX_DIST` variable, which controls the maximum backreference allowed in LZ parsing.

        [IMPROVEMENTS]

        - Better compression ratio in `lz77_compress()`.

        [CHANGES]

        - Renamed `bz2_compress` and `bz2_decompress` to `bwt_compress` and `bwt_decompress`, respectively.
        - Renamed `$LZSS_MIN_LEN` to `$LZ_MIN_LEN`.
        - Renamed `$LZSS_MAX_LEN` to `$LZ_MAX_LEN`.
        - Removed the `$LZ77_MIN_LEN` and `$LZ77_MAX_LEN` variables. Using `$LZ_MIN_LEN` and `$LZ_MAX_LEN` instead.

0.07    2024-05-12

        - Use the value of `$LZ_MAX_CHAIN_LEN` in `lz77_encode_symbolic()` as well.
        - Added the following package variables:

            $Compression::Util::LZSS_MIN_LEN
            $Compression::Util::LZSS_MAX_LEN
            $Compression::Util::LZ77_MIN_LEN
            $Compression::Util::LZ77_MAX_LEN

        ...which control the minimum and maximum lenght of a match in LZSS/lZ77 encoding.
        - Added support for exporting package variables with `use Compression::Util qw($PACKAGE_VARIABLE)`.

0.06    2024-05-05

        [ADDITIONS]

        - Added the lzss_encode_fast() function.
        - Added the lz77_compress_symbolic() and lz77_decompress_symbolic() functions.

        [IMPROVEMENTS]

        - Much faster algorithm in lzss_encode() for large enough strings.
        - Much better compression ratios achived by lzss_encode().
        - Extended lzss_compress() to accept an additional optional argument, specifying the LZSS encoding method.

        [CHANGES]

        - Removed the lzhd_compress() and lzhd_decompress() functions.
        - Renamed the mrl_compress() and mrl_decompress() to mrl_compress_symbolic() and mrl_decompress_symbolic(), respectively.
        - Simplified all functions to no longer take an optional output filehandle.

        [BUG-FIXES]

        - The output of delta_encode() is now always deterministic.

0.05    2024-04-13

        [ADDITIONS]

        - Added the mrl_compress() and mrl_decompress() functions.
        - Added the read_bit_lsb(), read_bits_lsb(), int2bits(), int2bits_lsb(), bits2int() and bits2int_lsb() functions.
        - Added the read_null_terminated() function.
        - Added the string2symbols() and symbols2string() functions.

        [IMPROVEMENTS]

        - Extended `huffman_from_*` to check the context and return only the encoding dictionary in scalar context.

        [CHANGES]

        - Simplified `lzss_encode()` for better performance, with a minimal impact on compression ratio.

        [BUG-FIXES]

        - Fixed several special cases and added more tests.

0.04    2024-04-06

        [ADDITIONS]

        - Added the deltas() and its inverse, accumulate(), functions.
        - Added the frequencies() function.
        - Added the huffman_from_symbols() function.
        - Added the huffman_from_code_lengths() function.

        [CHANGES]

        - Simplified deflate_encode() to always return a binary string (no longer writes to a file-handle).
        - Improved the delta_encode() function to also use RLE when it's beneficial.
        - Renamed huffman_tree_from_freq() to huffman_from_freq().

0.03    2024-03-22

        [ADDITIONS]

        - Added the lzhd_compress() and lzhd_decompress() functions.
        - Added the obh_encode() and obh_decode() functions.

        [CHANGES]

        - Simplified deflate_encode() to no longer require the size of the uncompressed data.

0.02    2024-03-21

        [ADDITIONS]

        - Added the run_length() function.
        - Added the binary_vrl_encode() and binary_vrl_decode() functions.
        - Added the elias_gamma_encode() and elias_gamma_decode() functions.
        - Added the adaptive_ac_encode() and adaptive_ac_decode() functions.
        - Added the create_adaptive_ac_entry() and decode_adaptive_ac_entry() functions.

        [CHANGES]

        - Renamed mtf_encode_alphabet() to encode_alphabet().
        - Renamed mtf_decode_alphabet() to decode_alphabet().

0.01    2024-03-21

        - Initial release.