On 22/11/2011 20:13, goldsi...@gmx.de wrote: > FreeRTOS Info wrote: >> Just in case anybody is watching this thread: >> >> As unlikely as this all seems, having previously isolated one file, I >> have now isolated it to a single function: lwip_standard_chksum(). >> >> I have the entire applicatino running at maximum optimisation, except >> this function, and everything is happy. >> >> Put the lowest optimisation on just this single function (which is now >> in its own file), and the network works, but with a lot of corruption on >> the wire. > Like Kieran and Stephen, I wouldn't rule out the possibility of a timing > issue, too. Especially since checksumming was the most time consuming > task in lwIP when I last benchmarked (aside of memcpy, but I guess you > haven't changed the amount of optimization of memcpy in your tests as it > often comes precompiled with the C library). > > Nevertheless, to prove the function fails, why don't you run a test on > random data comparing the results of the optimized checksum function > with a non-optimized version? You can even let that test run for a while > if you put the two functions into the same binary. If it's a compiler > bug or anything in that area, this test should show it.
Good thinking! Will do and report back. > > BTW: what do mean with 'a lot of corruption on the wire', invalid > checksums or more errors? It was described in a previous email. Sorry I have to run now but will be back online later this evening. I will explain it again when I post the results of the above mentioned test. Regards, Richard. _______________________________________________ lwip-users mailing list lwip-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/lwip-users