From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Courtier-Dutton Subject: Re: Re: About integer64 Date: Sat, 11 May 2002 16:19:27 +0100 Sender: alsa-devel-admin@lists.sourceforge.net Message-ID: <3CDD367F.4060906@superbug.demon.co.uk> References: <200205091339.g49Dd8907029@post2.fast.net> Reply-To: James@superbug.demon.co.uk Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: Errors-To: alsa-devel-admin@lists.sourceforge.net List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: To: Paul Davis Cc: Abramo Bagnara , Jaroslav Kysela , alsa-devel@lists.sourceforge.net List-Id: alsa-devel@alsa-project.org Paul Davis wrote: >>Not very much: >>a) if 32 bit integer could be enough expressive, what's the problem to >>truncate it in your driver? >> >> > >if i knew that this was true, i would do so. i don't know that. the >rms meters are the *only* registers on the h-dsp that are 64 bit, so i >assume there is some reason for this. > > > >>b) if a 32 bit integer is not enough and a float is preferrable: >>considered that an ieee754 floating point is in the form (1+man)*2^exp >>what's the problem in converting it in your driver using ffs and some >>shift? >> >> > >if the lkml crew see us using floating point in any form in the >kernel, we will attract complaints, even if we use integer operations >to do so. i am firmly convinced of this. > > > >>With both way I don't see the two point you make: >>1) why bother with signed vs unsigned >> >> > >for purity abramo! for purity! > > > >>2) why use 64 bit integer >> >>Of course if a 64 bit integer is the best way to represent/report the >>value all is fine, but in this case I doubt that you don't have >>available the 64th bit for the sign. >> >> > >that seems likely to me also. i suspect we have somewhere between 32 >and 64 bits of information. > >i didn't say that i conclusively needed the sign bit - i was noting >that the current API doesn't make unsigned values possible. > > > What is wrong with useing floats in the alsa-lib, and then casting them to uint64 for all calls to the kernel. That way, the kernel only ever sees a uint64, but the application sees a nice float. Cheers James _______________________________________________________________ Have big pipes? SourceForge.net is looking for download mirrors. We supply the hardware. You get the recognition. Email Us: bandwidth@sourceforge.net