Messages in this thread |  | | Date | Wed, 04 Sep 2002 15:41:19 -0700 | From | "H. Peter Anvin" <> | Subject | Re: TCP Segmentation Offloading (TSO) |
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Gabriel Paubert wrote: > On 3 Sep 2002, H. Peter Anvin wrote: > > [Sorry HPA, I forgot to cc to linux-kernel the first time.] > > >>>P.S. >>> Using "bswap" is little bit tricky. >>> >> >>It needs to be protected by CONFIG_I486 and alternate code implemented >>for i386 (xchg %al,%ah; rol $16,%eax, xchg %al,%ah for example.) > > > While it would work, this sequence is overkill. Unless I'm mistaken, the > only property of bswap which is used in this case is that it swaps even > and odd bytes, which can be done by a simple "roll $8,%eax" (or rorl). > > I believe that bswap is one byte shorter than roll. In any case, using a > rotate might be the right thing to do on other architectures. >
And again, I think you'll find the rotate faster on at least some x86 cores.
-hpa
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