1LZF(3) User Contributed Perl Documentation LZF(3)
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6 Compress::LZF - extremely light-weight Lempel-Ziv-Free compression
7
9 # import compress/decompress functions
10 use Compress::LZF;
11 # the same as above
12 use Compress::LZF ':compress';
13 $compressed = compress $uncompressed_data;
15 $original_data = decompress $compressed;
16 # import sfreeze, sfreeze_cref and sfreeze_c
18 use Compress::LZF ':freeze';
19 $serialized = sfreeze_c [4,5,6];
21 $original_data = sthaw $serialized;
22
24 LZF is an extremely fast (not that much slower than a pure memcpy)
25 compression algorithm. It is ideal for applications where you want to
26 save some space but not at the cost of speed. It is ideal for
27 repetitive data as well. The module is self-contained and very small
28 (no large library to be pulled in). It is also free, so there should be
29 no problems incorporating this module into commercial programs.
30 I have no idea wether any patents in any countries apply to this
32 algorithm, but at the moment it is believed that it is free from any
33 patents.
34
36 $compressed = compress $uncompressed
37 Try to compress the given string as quickly and as much as
38 possible. In the worst case, the string can enlarge by 1 byte, but
39 that should be the absolute exception. You can expect a 45%
40 compression ratio on large, binary strings.
41 $decompressed = decompress $compressed
43 Uncompress the string (compressed by "compress") and return the
44 original data. Decompression errors can result in either broken
45 data (there is no checksum kept) or a runtime error.
46 $serialized = sfreeze $value (simplified freeze)
48 Often there is the need to serialize data into a string. This
49 function does that, by using the Storable module. It does the
50 following transforms:
51 undef (the perl undefined value)
53 => a special cookie (undef'ness is being preserved)
54 IV, NV, PV (i.e. a _plain_ perl scalar):
55 => stays as is when it contains normal text/numbers
56 => gets serialized into a string
57 RV, undef, other funny objects (magical ones for example):
58 => data structure is freeze'd into a string.
59 That is, it tries to leave "normal", human-readable data untouched
61 but still serializes complex data structures into strings. The idea
62 is to keep readability as high as possible, and in cases
63 readability can't be helped anyways, it tries to compress the
64 string.
65 The "sfreeze" functions will enlarge the original data one byte at
67 most and will only load the Storable method when neccessary.
68 $serialized = sfreeze_c $value (sfreeze and compress)
70 Similar to "sfreeze", but always tries to "c"ompress the resulting
71 string. This still leaves most small objects (most numbers)
72 untouched.
73 The "sfreeze_c" function uses a different algorithm that is slower
75 but usually achieves better compression.
76 $serialized = sfreeze_cr $value (sfreeze and compress references)
78 Similar to "sfreeze", but tries to "c"ompress the resulting string
79 unless it's a "simple" string. References for example are not
80 "simple" and as such are being compressed.
81 $original_data = sthaw $serialized
83 Recreate the original object from it's serialized representation.
84 This function automatically detects all the different sfreeze
85 formats.
86 Compress::LZF::set_serializer $package, $freeze, $thaw
88 Set the serialize module and functions to use. The default is
89 "Storable", "Storable::net_mstore" and "Storable::mretrieve", which
90 should be fine for most purposes.
91
93 This module supports the perl multicore specification
94 (<http://perlmulticore.schmorp.de/>) for all compression (> 2000
95 octets) and decompression (> 4000 octets) functions.
96
98 "compress_best" and other _best subroutines were removed because
99 liblzf-3.6 does not yet support them. See
100 <https://bugzilla.redhat.com/show_bug.cgi?id=1268333>.
101
103 Other Compress::* modules, especially Compress::LZV1 (an older, less
104 speedy module that guarentees only 1 byte overhead worst case) and
105 Compress::Zlib.
106 http://liblzf.plan9.de/
108
110 This perl extension and the underlying liblzf were written by Marc
111 Lehmann <schmorp@schmorp.de> (See also http://liblzf.plan9.de/).
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114perl v5.30.0 2019-07-26 LZF(3)