RE: RE: [lwip-users] Sizes

[Bill Auerbach]

John, if you're using a little endian processor, I've posted a patch (in the 
patch section) that made some improvement for me.

Bill

>-----Original Message-----
>From: address@hidden
>[mailto:address@hidden On
>Behalf Of John Kennedy
>Sent: Thursday, May 28, 2009 9:17 AM
>To: Mailing list for lwIP users
>Subject: RE: RE: [lwip-users] Sizes
>
>Well, just for fun I switched to algorithm 3 and got a 100Kbits/s
>improvement.
>
>John
>
>
>
>________________________________________
>John Kennedy
>
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>-----Original Message-----
>From: Simon Goldschmidt [mailto:address@hidden
>Sent: Thursday, May 28, 2009 1:16 AM
>To: Mailing list for lwIP users
>Subject: Re: RE: [lwip-users] Sizes
>
>
>> BTW which checksum algorithm did base your
>> assembly code on?  Does anyone know which of the checksum algorithms
>is the
>> fastest?
>
>Unfortunately, that depends largely on your platform. The best thing to
>do is to try all of them: call them in a loop on a data buffer that is
>bigger than your caches and see which one finishes first.
>
>> I'm a little surprised that other than the call overhead that an
>> assembly version of memcpy is much faster than what the complier
>produces from the library?
>
>The difference here is not C or assembly but 'standard' library (written
>in C, used on many platforms) or hand-written code that performs well on
>your specific platform. And let me tell you there *is* room for
>improvement here. For example, some C libraries use byte-by-byte copy if
>compiled with the 'wrong' options... Nevertheless, the standard library
>often is not too bad when copying a well-aligned source to a well-
>aligned destination.
>
>Simon
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