Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sources.redhat.com/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sources.redhat.com/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com
Message-ID: <3F09D357.1010901@cern.ch>
Date: Mon, 07 Jul 2003 22:08:55 +0200
From: "Lassi A. Tuura" <lassi DOT tuura AT cern DOT ch>
Organization: Northeastern University, Boston, USA
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4a) Gecko/20030401
X-Accept-Language: en-us, en
MIME-Version: 1.0
To: Martin Gainty <mgainty AT hotmail DOT com>
CC: cygwin AT cygwin DOT com
Subject: Re: restrict
References: <Law10-OE12jj0aImPiZ00001387 AT hotmail DOT com>
In-Reply-To: <Law10-OE12jj0aImPiZ00001387@hotmail.com>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

> I have never seen restrict keyword..any ideas?

It was introduced in C99, and in a few compilers before that.  Roughly
speaking it means the memory pointed to by the restrict pointer is not
aliased by anything else visible in that scope, so the compiler is free
to optimise the code assuming no other pointer write writes over memory.

Take for example:
  int foo (int *restrict a, int *restrict b)
  { a[1] = b[1]; return b[0] + a[1]; }

The compiler can assume the assignment to a[1] will not have modified b[0].

Hope this helps,
//lat
-- 
The stone fell on the pitcher? Woe to the pitcher. The
pitcher fell on the stone? Woe to the pitcher.
	--Rabbinic Sayning


--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Problem reports:       http://cygwin.com/problems.html
Documentation:         http://cygwin.com/docs.html
FAQ:                   http://cygwin.com/faq/