Module: Omnizip::Algorithms::Zstandard::Constants

Included in:
Decoder, Encoder, FSE::Encoder, FSE::Table, Frame::Block, Frame::Header, Huffman, HuffmanEncoder, HuffmanTableReader, LiteralsDecoder, LiteralsEncoder, SequenceExecutor, SequencesDecoder
Defined in:
lib/omnizip/algorithms/zstandard/constants.rb

Overview

Constants from RFC 8878 (Zstandard Compression)

See Also:

Constant Summary collapse

MAGIC_NUMBER =

Frame Constants

0xFD2FB528
MAGIC_BYTES = 
[0x28, 0xB5, 0x2F, 0xFD].freeze
SKIPPABLE_MAGIC_BASE = 
0x184D2A50
SKIPPABLE_MAGIC_MASK = 
0xFFFFFFF0
BLOCK_TYPE_RAW =

Block Types (RFC 8878 Section 3.1.1.2)

0
BLOCK_TYPE_RLE = 
1
BLOCK_TYPE_COMPRESSED = 
2
BLOCK_TYPE_RESERVED = 
3
BLOCK_HEADER_SIZE = 
3
BLOCK_MAX_SIZE = 
128 * 1024
LITERALS_BLOCK_RAW =

Literals Block Types (RFC 8878 Section 3.1.1.3.1)

0
LITERALS_BLOCK_RLE = 
1
LITERALS_BLOCK_COMPRESSED = 
2
LITERALS_BLOCK_TREELESS = 
3
HUFFMAN_MAX_BITS = 
11
MODE_PREDEFINED =

Sequence Compression Modes (RFC 8878 Section 3.1.1.3.2)

0
MODE_RLE = 
1
MODE_FSE = 
2
MODE_REPEAT = 
3
LITERALS_LENGTH_ACCURACY_LOG =

FSE Accuracy Logs (RFC 8878 Section 4)

6
MATCH_LENGTH_ACCURACY_LOG = 
6
OFFSET_ACCURACY_LOG = 
5
REPEAT_OFFSET_1 =

Repeat Offsets (RFC 8878 Section 3.1.2.2.3)

1
REPEAT_OFFSET_2 = 
2
REPEAT_OFFSET_3 = 
3
DEFAULT_REPEAT_OFFSETS = 
[1, 4, 8].freeze
WINDOW_LOG_MIN =

Window Constants (RFC 8878 Section 3.1.1.1.2)

10
WINDOW_LOG_MAX = 
41
HUFFMAN_MAX_LOG =

Huffman Constants (RFC 8878 Section 4.2.1)

11
HUFFMAN_MAX_CODE_LENGTH = 
11
HUFFMAN_STANDARD_TABLE_SIZE = 
256
FSE_MAX_ACCURACY_LOG =

FSE Table Limits (RFC 8878 Section 4.1)

9
FSE_MIN_ACCURACY_LOG = 
5
MIN_LEVEL =

Compression levels

1
MAX_LEVEL = 
22
DEFAULT_LEVEL = 
3
BUFFER_SIZE =

Buffer size for streaming operations

128 * 1024
LITERAL_LENGTH_TABLE =

Literal length codes (RFC 8878 Table 9) Each entry: [baseline, extra_bits]

[
  [0, 0], [1, 0], [2, 0], [3, 0], [4, 0], [5, 0], [6, 0], [7, 0],
  [8, 0], [9, 0], [10, 0], [11, 0], [12, 0], [13, 0], [14, 0], [15, 0],
  [16, 1], [18, 1], [20, 1], [22, 1], [24, 1], [28, 1], [32, 1], [40, 1],
  [48, 1], [64, 1], [128, 2], [256, 2], [512, 2], [1024, 2], [2048, 2],
  [4096, 2], [8192, 2], [16384, 3], [32768, 3], [65536, 3]
].freeze
MATCH_LENGTH_TABLE =

Match length codes (RFC 8878 Table 10) Each entry: [baseline, extra_bits]

[
  [3, 0], [4, 0], [5, 0], [6, 0], [7, 0], [8, 0], [9, 0], [10, 0],
  [11, 0], [12, 0], [13, 0], [14, 0], [15, 0], [16, 0], [17, 0], [18, 0],
  [19, 0], [20, 0], [21, 0], [22, 0], [23, 0], [24, 0], [25, 0], [26, 0],
  [27, 0], [28, 0], [29, 0], [30, 0], [31, 0], [32, 0], [33, 0], [34, 0],
  [35, 1], [37, 1], [39, 1], [41, 1], [43, 1], [47, 1], [51, 1], [59, 1],
  [67, 1], [83, 1], [99, 1], [131, 2], [195, 2], [259, 2], [323, 2],
  [387, 2], [451, 2], [515, 2], [579, 2], [643, 2], [707, 2], [771, 2],
  [835, 2], [899, 2], [963, 2], [1027, 2], [1283, 2], [1539, 2],
  [1795, 2], [2051, 2], [2307, 2], [2563, 2]
].freeze
PREDEFINED_LL_DISTRIBUTION =

Predefined FSE distribution for literals length (RFC 8878 Section 4.1.3)

[
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  4, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
  0, 0, 0, 0
].freeze
PREDEFINED_ML_DISTRIBUTION =

Predefined FSE distribution for match length (RFC 8878 Section 4.1.3) Sum = 64 (must equal 2^6 = 64)

[
  1, 4, 3, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1,
  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
].freeze
PREDEFINED_OFFSET_DISTRIBUTION =

Predefined FSE distribution for offset (RFC 8878 Section 4.1.3)

[
  1, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 1, 1, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
].freeze