Module Fat_update

type data =
| String of string
| Cstruct of Cstruct.t(*

payload of a buffer update

*)
type t = {
offset : int64;
data : data;
}

an update to a block of data (which may be in memory or on disk or somewhere else)

val to_string : t -> string
val from_string : int64 -> string -> t
val from_cstruct : int64 -> Cstruct.t -> t
val shift : int64 -> t -> t
val total_length : t -> int64

total_length x returns the minimum size of the block of data needed to apply this update. If the block is currently smaller then it will need to be enlarged

val apply : Cstruct.t -> t -> unit

apply buf update updates buf with update

val clip : t -> int64 -> int -> t

clip x offset length returns the fraction of the update between offset and offset+length in bytes

val is_empty : t -> bool
val split : t -> int -> t list

split x sector_size returns x as a sequence of consecutive updates, each of which corresponds to a region of length sector_size. Note empty updates are omitted.

val map : t list -> int list -> int -> t list

map xs offsets takes a sequence of virtual sector updates (eg within the virtual address space of a file) and a sequence of physical offsets (eg the location of physical sectors on disk) and returns a sequence of physical sector updates.