On 03/26/2013 10:51 PM Matt Turner wrote:
On Tue, Mar 26, 2013 at 2:44 PM, Bengt Richter<[email protected]> wrote:
uint32_t
component_delta2(uint32_t next, uint32_t prev)
{
return ((((next&0xff00ff)-(prev&0xff00ff)+0x100)&0xff00ff)+
(((next&0xff00)-(prev&0xff00))&0xff00));
}
Does removing all the spaces make it faster? ;)
LOL .. actually I didn't put them in in the first place ;-)
But inlining might make the calling loop faster.
Hm, easy to try now ... inlining cut the time in almost in half again.
I assigned to a volatile so the loop wouldn't get optimized away.
I just have a loop in the test kludge like
else if (strcmp(argv[1],"v2")==0){
for (i=0;i<256*256*256;++i){
antiO2 = component_delta2(i, i^0xffffff);
}
}
For the above with inlined component_delta2 I get
55ms vs 95ms not inlined, vs orig not inlined 167ms, FWIW.
My optimization reflex just got triggered, I didn't look at the
full post context to see if it might really be useful or not.
Regards,
Bengt Richter
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