Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!ucsd!ucbvax!agate!e260-3f!c60c-3cf
From: c60c-3cf@e260-3f.berkeley.edu (Dan Kogai)
Newsgroups: comp.unix.wizards
Subject: Re: fastest way to copy hunks of memory
Summary: How about the following?
Keywords: bcopy, memcpy
Message-ID: <1990May4.172145.4085@agate.berkeley.edu>
Date: 4 May 90 17:21:45 GMT
References: <5531@helios.ee.lbl.gov> <1990May2.200732.11851@eci386.uucp>
Sender: usenet@agate.berkeley.edu (USENET Administrator;;;;ZU44)
Organization: UC Bezerkeley
Lines: 34

In article <1990May2.200732.11851@eci386.uucp> clewis@eci386.UUCP (Chris Lewis) writes:
>Perhaps 
>
>    while(size--)
>	*p1++ = *p2++;

or even

void *memcpy(void *to, void *from, size_t size){
	register int 	size_l = size / 4,	/* or (size >> log2(sizeof int)) */
					tail = size % 4;	/* or (size & log2(sizeof int)) */
	void			*result = to;				
	while(size_l--) (int *)to++ = (int *)from++;
	while(tail--) (char *)p1++ = (char *)p2++;
	return result;
}

	This shold work almost 4 times as fast compared to just inclementing
by bytes--it uses full length of register.  The problem is that it doesn't
work if either (void *to) and (void *from) is not aligned and the macine
architecure doesn't allow unaligned assignment.  Such functions as
memcpy() should be written in assembler, I think...

---
##################  Dan The "ioccc contestant this year" Man
+ ____  __  __   +  (Aka Dan Kogai)
+     ||__||__|  +  E-mail:     dankg@ocf.berkeley.edu
+ ____| ______   +  Voice:      415-549-6111
+ |     |__|__|  +  USnail:     1730 Laloma Berkeley, CA 94709
+ |___  |__|__|  +              U.S.A
+     |____|____ +  Disclaimer: I'd rather be blackmailed for my long .sig
+   \_|    |     +              than give up my cool name in Kanji. And my
+ <- THE MAN  -> +              citizenship of People's Republic o' Berkeley
##################              has nothing 2 do w/ whatever I post, ThanQ.