Re: [quicwg/base-drafts] QPACK: wrap absolute index values (#1657)

[Dmitri Tikhonov <[e-mail]>]

dtikhonov commented on this pull request.



> -necessary for decoding. If the greatest absolute index in the dynamic table is
-less than the value of the Largest Reference, the stream is considered
-"blocked."  While blocked, header field data should remain in the blocked
-stream's flow control window.  When the Largest Reference is zero, the frame
-contains no references to the dynamic table and can always be processed
-immediately. A stream becomes unblocked when the greatest absolute index in the
-dynamic table becomes greater than or equal to the Largest Reference for all
+Each header block contains a Largest Reference field which identifies the
+table state necessary for decoding.
+
+When the Largest Reference value is not specified, the frame contains no
+references to the dynamic table and can always be processed immediately.
+
+When it is specified, the Largest Reference value is compared with
+the absolute index value of the next entry to be inserted into the
+dynamic table.  That entry's absolute index value divides the absolute

I used the "next entry to be inserted" because I see no other way to describe the initial state, when there is no "last inserted entry."  Perhaps we could add the concept of "cursor?"

The "total number of inserts" concept eludes me.  The diagram is confusing, as it combines both encoder instructions (`Insert`) and header block instructions (`Post-Base`).

1. If the "total number of inserts" is the number of inserts performed while encoding a given header block, how does the decoder know where to start?
1. If this number is added to the current absolute index, then it is the same as _Largest Reference_.
1. ?

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/quicwg/base-drafts/pull/1657#discussion_r209944304