Module Rfc1951.Lz77

Lz77 algorithm.

A functionnal non-blocking implementation of Lz77 algorithm. This algorithm produces a Hunk.t list of an input.

This algorithm is the same as https://github.com/Blosc/c-blosc. So the implementation is an imperative hack in OCaml. May be it's not the best in the functionnal world but it works. The interface was thinked to be replaced by your implemenation by a functor.

type error =
| Invalid_level of int

This error appears when you try to compute the Lz77 algorithm with a wrong level (level >= 0 && level <= 9).

| Invalid_wbits of int

This error appears when you specify a bad wbits: wbits >= 8 && wbits <= 15

Lz77 error.

type 'i t

The state of the Lz77 algorithm.

val pp_error : Stdlib.Format.formatter -> error -> unit

Pretty-printer of Lz77 error.

val pp : Stdlib.Format.formatter -> 'i t -> unit

Pretty-printer of Lz77 state.

val used_in : 'i t -> int

used_in t returns n bytes(s) used by the algorithm in the current input.

val default : witness:'i Buffer.t -> ?⁠level:int -> ?⁠on:(Hunk.t -> unit) -> int -> 'i t

default ~witness ~level ~on wbits produces a new state to compute the Lz77 algorithm in an input. level means the level of the compression (between 0 and 9), on is a function called when the algorithm produce one Hunk.t and wbits is the window size allowed.

Usually, wbits = 15 for a window of 32K. If wbits is lower, you constraint the distance of a Match produced by the Lz77 algorithm to the window size.

on is a function to interact fastly with your data-structure and keep frequencies of Literal and Match.