The Map tree zhich zill represent the IDX file of the PACK stream.
The type of the reference. It's a negative offset or the hash of the source object.
refill off len t provides a new t with len bytes to read, starting at off. This byte range is read by calls to eval with t until `Await is returned. The encoder expects the target raw (not the source) to write Insert opcodes. The client must send the target raw continuously because internally, we assert than a continuous stream of the target raw and pick only the needed byte range.
flush off len t provides t with len bytes to write, starting at off. This byte range is written by calls to eval with t until `Flush is returned.
finish t provides a new t which does not expect any input. An eval of the new t will never return an `Await value then.
val eval :
Cstruct.t ->
Cstruct.t ->
t ->
[ `Await of t | `Flush of t | `End of t | `Error of t * error ]eval src t is:
`Await t iff t needs more input storage. The client must use refill to provide a new buffer and then call eval with `Await until other value returned.`Flush t iff t needs more output storage. The client must use flush to provide a new buffer and then call eval with `Flush until `End is returned.`End t when t is done. Then, t sticks on this situation, the client can remove it.`Error (t, exn) iff the encoder t meet an error exn. The encoder can't continue and sticks in this situation.