Module: Omnizip::Algorithms::PPMd7::Constants

Included in:

Omnizip::Algorithms::PPMd7, Context, Model

Defined in:

lib/omnizip/algorithms/ppmd7/constants.rb

Overview

Constants for PPMd7 algorithm

PPMd7 uses context-based statistical compression with maximum context orders typically ranging from 2 to 16.

Constant Summary

MAX_ORDER =

Maximum context order (model order)

16

MIN_ORDER =

2

DEFAULT_ORDER =

6

MIN_MEM_SIZE =

Memory allocation constants

1 << 20

MAX_MEM_SIZE =

1 MB minimum

1 << 30

DEFAULT_MEM_SIZE =

1 GB maximum

1 << 24

PROB_TOTAL =

Probability scaling factors

2048

MAX_FREQ =

124

INIT_ESCAPE_FREQ =

1

ALPHABET_SIZE =

Symbol alphabet size

256

UNIT_SIZE =

Context node structure sizes

12

MAX_STATES =

Maximum number of states per context

256

SEE_CONTEXTS =

Escape symbol handling

25

SUFFIX_CONTEXTS =

32

INT_BITS =

Update intervals for probability models

7

PERIOD_BITS =

7

BIN_SCALE =

1 << 13

INTERVAL =

1 << INT_BITS

UNIT_ALLOC_SIZE =

Memory unit allocation

12

TOP_VALUE =

Range coder constants (inherited from arithmetic coding)

1 << 24

BOT_VALUE =

1 << 15