[SERVER-57781] Extend Simple-8b Selectors using padding bits to encode bit shift Created: 17/Jun/21  Updated: 29/Oct/23  Resolved: 28/Jul/21

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: None
Fix Version/s: 5.1.0-rc0

Type: Task Priority: Major - P3
Reporter: Henrik Edin Assignee: Luke Bhan (Inactive)
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Backwards Compatibility: Fully Compatible
Sprint: Execution Team 2021-07-12, Execution Team 2021-07-26, Execution Team 2021-08-09
Participants:

 Description   

Regular Simple-8b will encode blocks in the buckets the following way

Nr ValueBits Elems Padding
1	1              60    0
2	2              30    0
3	3              20    0
4	4              15    0
5	5              12    0
6	6              10    0
7	7               8     4
8	8               7     4
9	10             6     0
10	12             5     0
11	15             4     0
12	20             3     0
13	30             2     0
14	60             1     0

The four padding bits in selector 7 and 8 can be used to extend the amount of selectors. We want to use them to describe a bit shift where large values with many trailing zeros can be compressed efficiently.

SelectorNr    PaddingValue    Elems    ValueBits    ShiftBits
7                   1            9           2          4
7                   2            8           3          4
7                   3            7           4          4
7                   4            6           5          4
7                   5            5           7          4
7                   6            4           10         4
7                   7            3           14         4
7                   8            2           24         4
7                   9            1           52         4

Extend Simple-8b encoder/decoder to handle these extended selectors.

Extend calculation of optimal selector to handle these values too.



 Comments   
Comment by Vivian Ge (Inactive) [ 06/Oct/21 ]

Updating the fixversion since branching activities occurred yesterday. This ticket will be in rc0 when it’s been triggered. For more active release information, please keep an eye on #server-release. Thank you!

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