Proposal for new structure definition for compression algorithm
nhofmeyr at sysmocom.de
Tue Mar 22 16:00:13 UTC 2016
I should probably also read all of the code involved, properly, which I
must admit I haven't, but based on general knowledge, my replies are:
On Tue, Mar 22, 2016 at 10:22:59AM +0000, Sangamesh Sajjan wrote:
> The proposed structures are being used in following scenario.
> 1. System Init (i.e. During system bootup)
> * Array of strings are used to form a tree, it is used only once during system bootup , hence it should not impact the performance. Let me know your opinion on this ?
Ok, for once-upon-boot a string approach sounds fair enough.
> 2. Decoding of EGPRS packet downlink Ack/Nack
> * While decoding there is no string comparison involved, we read every bit from the bitmap and traverse tree generated in init, hence only bit operation involved in decoding.
> 3. Encoding of packet uplink Ack/Nack
> * While encoding, first find the number of one's/zero's (i.e. run length of one's or zero's) consecutively and find the corresponding code word by referring to the code word list
> * This involves string comparison to find the code word,
> but based on your feedback we are planning to avoid string operations
> and adopt existing (i.e. master ) approach to find the code word by using respective tables.
Sounds much better, yes.
> In current master code for decoding, the function t4_rle_term is used to find the run length for each received code word,
> There could be multiple code words in the received bitmap and each require multiple iterations(i.e. maximum of 64 iterations) to find run length.
> Instead if tree based approach is used multiple iterations can be avoided to find run length.
Is this a separate suggestion to introduce a binary tree search? Beware of
too heavy / premature optimizations, but your trajectory sounds way better
Anyway, looking forward to the patches, and I hope to read the patch
context properly, then. Thanks!
- Neels Hofmeyr <nhofmeyr at sysmocom.de> http://www.sysmocom.de/
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