Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!bellcore!faline!thumper!ulysses!andante!alice!andrew
From: andrew@alice.UUCP (Andrew Hume)
Newsgroups: comp.unix.questions
Subject: Re: bcopy
Summary: implementation note
Message-ID: <8522@alice.UUCP>
Date: 12 Dec 88 04:58:45 GMT
References: <9095@smoke.BRL.MIL> <9167@ihlpb.ATT.COM> <1356@astroatc.UUCP> <669@auspex.UUCP>
Organization: AT&T Bell Laboratories, Murray Hill NJ
Lines: 12



don't let the twerps responsible for the memcpy/memmove debacle blind
implementers. memcpy and memmove should be the same entry point;
the test for overlapping regions is only a few instructions and just doesn't
matter in any practical timing sense. If the bytecount is at all significant,
initial overhead is irrelevent and if teh bytecount is small, then the
subroutine call overhead is probably 2-3 times more expensive than the
check.
	in any case, in a lot of hardware, overlapping doesn't matter;
what matters is left to right or right to left.
	does anyone know of any case where the above analysis fails?