Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763868AbXJEUEa (ORCPT ); Fri, 5 Oct 2007 16:04:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759853AbXJEUEW (ORCPT ); Fri, 5 Oct 2007 16:04:22 -0400 Received: from mail.suse.de ([195.135.220.2]:34915 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759624AbXJEUEV (ORCPT ); Fri, 5 Oct 2007 16:04:21 -0400 From: Andreas Schwab To: Timur Tabi Cc: Jan Engelhardt , Linux Kernel Mailing List Subject: Re: __LITTLE_ENDIAN vs. __LITTLE_ENDIAN_BITFIELD References: <4706822D.4070509@freescale.com> <470691EB.7020209@freescale.com> <470694E0.7030408@freescale.com> X-Yow: It's a lot of fun being alive... I wonder if my bed is made?!? Date: Fri, 05 Oct 2007 22:04:18 +0200 In-Reply-To: <470694E0.7030408@freescale.com> (Timur Tabi's message of "Fri\, 05 Oct 2007 14\:47\:44 -0500") Message-ID: User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/22.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1279 Lines: 30 Timur Tabi writes: > I'm writing a driver that talks to hardware that has a shift register. > The register can be shifted either left or right, so all the bits > obviously have to be in order, but it can be either order. Bit addressing is strictly internal to the cpu, the smallest unit that the cpu can address externally is a byte. The only place where bit order matters on the C level is in a bitfield that is overlayed over a block of memory, but this is not visible outside the cpu. > What I want to do is to have the driver detect when byte-endianness > doesn't match bit-endianness when it writes the the word to a > memory-mapped device. The bit mapping on your device is strictly internal to the device and has nothing to do with bit order on the C level. Andreas. -- Andreas Schwab, SuSE Labs, schwab@suse.de SuSE Linux Products GmbH, Maxfeldstra?e 5, 90409 N?rnberg, Germany PGP key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/