[lwip-devel] [bug #46278] The wraparound case for getting difference between 2 u32_t value needs fix

[Axel Lin]

URL:
  <http://savannah.nongnu.org/bugs/?46278>

                 Summary: The wraparound case for getting difference between 2
u32_t value needs fix
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: axellin
            Submitted on: Fri 23 Oct 2015 08:20:46 AM GMT
                Category: None
                Severity: 3 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: 
            lwIP version: git head

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Details:

Hi,
The commit cf1be4ae2d2b80b87df9b1e199e60e301ce6d1c5
"fixed bug #34541: LWIP_U32_DIFF is unnecessarily complex: removed that
define"

looks wrong to me in the wrap around case.
For example, if now is wrap around to 0 and timeouts_last_time is 4294967293.
The correct diff is: 3
but with current code, the diff is: 4294967293.

I think that commit needs to be reverted.
comments?





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