On Jan 16, 2012, at 07:53, robin wrote: > From: "Dan Skomsky, PSTI" <[email protected]> > Sent: Monday, 16 January 2012 11:49 PM > >> One Assembler trick I have seen in speeding up scanning loops was to use a >> CLI instruction to check the first byte of a string and then only doing the >> CLC/CLCL if the CLI matches. This trick even works if doing a binary >> search. > On the average (FSVO), how does this compare Boyer-Moore?
I've seen suggested TRT for the first character, then CLC for the rest. Works much better for strings beginning with "Z" than for strings beginning with " ". > Marginal savings, I think, compared to EX/CLC or CLCL, > for the reason that both CLC and CLCL give up after examining the > first character, should they be unequal. > > Might be more fruitful to compare length of the key with that of an element > first, > and then carrrying out the compare should those lengths be equal. > Gives you "=", but not "<" or ">", so precludes binary search. What was the statement of the problem, anyway? CDC 3600/3800 had a "Modify following instruction" instruction that met much of the requirement for EX. And pipelining was of little import in that era. -- gil
