On Mon, Jun 18, 2007 at 01:07:26PM -0700, Bart Smaalders wrote:
<mucho snippage deleted!>
> On x86, why not inline a bswap instruction?
That *is* the actual implementation of htons()/ntohs(). Here, check it out!
>From $SRC/uts/intel/ia32/ml/ia32.il:
/
/ Networking byte order functions (too bad, Intel has the wrong byte order)
/
.inline htonl,4
movl (%esp), %eax
bswap %eax
.end
.inline ntohl,4
movl (%esp), %eax
bswap %eax
.end
.inline htons,4
movl (%esp), %eax
bswap %eax
shrl $16, %eax
.end
.inline ntohs,4
movl (%esp), %eax
bswap %eax
shrl $16, %eax
.end
and from $SRC/uts/intel/amd64/ml/amd64.il:
/
/ Networking byte order functions (too bad, Intel has the wrong byte order)
/
.inline htonl,4
movl %edi, %eax
bswap %eax
.end
.inline ntohl,4
movl %edi, %eax
bswap %eax
.end
.inline htons,4
movl %edi, %eax
bswap %eax
shrl $16, %eax
.end
.inline ntohs,4
movl %edi, %eax
bswap %eax
shrl $16, %eax
.end
I didn't show DTrace numbers for the "htonl() the big-endian version" in my
previous post, but it was slower than the table-lookup whose numbers I did
share.
Dan
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