X-Recipient: archive-cygwin AT delorie DOT com X-Spam-Check-By: sourceware.org Date: Tue, 11 Jan 2011 17:54:39 -0500 From: Christopher Faylor To: cygwin AT cygwin DOT com Subject: Re: drand48() (and erand48) returns only zeros and pthread application problems - in cygwin 1.7.8 returns always same values Message-ID: <20110111225439.GA24015@ednor.casa.cgf.cx> Reply-To: cygwin AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com Delivered-To: mailing list cygwin AT cygwin DOT com On Tue, Jan 11, 2011 at 11:50:14AM +0100, jdzstz - gmail dot com wrote: >About all the problems with drand48, explained in: > * http://www.cygwin.com/ml/cygwin/2010-12/msg00460.html > >Christopher Faylor fixed it in 20101229 snapshot: >http://www.cygwin.com/snapshots/winsup-changelog-20101226-20101229 > >I have realized that the fix does not work as expected, it is used >thread memory address to initialize srand48 with srand48 ((long int) >&x); > >--- winsup-src-20101226/cygwin-snapshot-20101226-1/winsup/cygwin/cygtls.cc 2010-02-28 >15:55:33.000000000 +0000 >+++ winsup-src-20101229/cygwin-snapshot-20101229-1/winsup/cygwin/cygtls.cc 2010-12-29 >06:34:24.000000000 +0000 >@@ -94,4 +95,5 @@ _cygtls::init_thread (void *x, DWORD (*f > local_clib._current_locale = "C"; > locals.process_logmask = LOG_UPTO (LOG_DEBUG); >+ srand48 ((long int) &x); > } > >Now, drand48 doesnot returns zero in thread, but the problem is that >in every execution the adress should be the same, because it returns >always the same values. Right. That was exactly the point. If you want more randomness then seed this yourself. Linux always provides a fixed series of numbers when srand48 has not been called too. cgf -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple