[lwip-devel] [patch #6537] wnd_scale TCP option addition

[Simon Goldschmidt]

Follow-up Comment #3, patch #6537 (project lwip):

Bill wrote:
>> So, if we agree that we need to keep rcv_ann_wnd and snd_wnd as u32_t,
> 
> Why when tcp_hdr wnd is u16_t?  If ultimately it gets truncated, 
> no sense bloating code for u32_t until the final use of it.  8 
> bit processors don't do s/u32_t very efficiently and so the use 
> of s/u32_t should be minimized.

The window sizes are supposed to be 32 bit values, so at some point we would
have to calculate with them as 32 bit values. You can either store them as 32
bit or store them as 16 bit and shift to 32 bit (using scale factor) on load.
I think storing as 32 bit is the better alternative.

(BTW: you are welcome to reply to the bugtracker system for patches!)

re Jonathan 1):
I thought that's the whole meaning of window scaling: to have windows bigger
than 64KByte!

re Jonathan 2):
This is indeed true. Having more than 64K pbufs queued on a single PCB seems
highly unlikely!



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