Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site decvax.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!allegra!mit-eddie!genrad!decvax!minow
From: minow@decvax.UUCP (Martin Minow)
Newsgroups: net.lang.c
Subject: Re: String copy idiom.
Message-ID: <55@decvax.UUCP>
Date: Tue, 12-Mar-85 21:02:19 EST
Article-I.D.: decvax.55
Posted: Tue Mar 12 21:02:19 1985
Date-Received: Thu, 14-Mar-85 04:40:52 EST
References: <2040@sun.uucp>
Lines: 17

On a vax, the fastest string copy is probably the non-obvious

	length = strlen(input);
	strncpy(output, input, length);

(Assuming both routines are expanded in-line so you're not
hit by the subroutine call overhead.)  Note the following
VMS Macro code from a routine in the Decus C library.

	.entry	strcpy,^M<r2,r3,r4,r5>
	movl	8(ap),r2	; source string
	locc	#0,#-1,(r2)	; find null at end of source
	subl2	r2,r1		; length of source
	incl	r1		; plus 1 for the null byte
	movc3	r1,@8(ap),@4(ap); copy the string
	movl	4(ap),r0	; r0 -> destination
	.end