Saturday, January 22, 2005

Devisive

Duffs device
The original usenet posting
Google 20 year usenet timeline

I first saw this a few weeks back on googles 20 year usenet timeline. Sometimes optimisation can be so cool.


send(to, from, count)
register short *to, *from;
register count;
{
register n=(count+7)/8;
switch(count%8){
case 0: do{ *to = *from++;
case 7: *to = *from++;
case 6: *to = *from++;
case 5: *to = *from++;
case 4: *to = *from++;
case 3: *to = *from++;
case 2: *to = *from++;
case 1: *to = *from++;
}while(--n>0);
}
}