27-Aug-2013 18:41, H. S. Teoh пишет:
On Tue, Aug 27, 2013 at 07:37:02AM -0700, Sean Kelly wrote:
On Aug 26, 2013, at 11:57 PM, monarch_dodra <monarchdo...@gmail.com> wrote:
For performance reasons, I need a "w" version of memchr.
C defines wmemchr as:
wchar_t * wmemchr ( const wchar_t *, wchar_t, size_t );
Unfortunatly, on unix, "wchar_t" is defined a *4* bytes long,
making wmemchr, effectivelly, "dmemchr".
Are there any "2 byte" alternatives for wmemchr on unix?
Why not cast the array to ushort[] and do a find()? Or is that too
slow as well?
Optimized searches of this kind ideally translate to the various rep*
instructions on x86.
Rather a loop with XMM moves. What's best though is always a moving target.
I'm not sure if dmd does that optimization. If you
really feel inclined, you could do static if (X86) and throw in an asm
block (but that would break purity, @safety, etc., so probably not a
good idea).
It would be awesome to have pure D analogs for memchr, memcpy and its
ilk that won't be so limiting (as in types used) but would guarantee top
performance.
--
Dmitry Olshansky
