From mboxrd@z Thu Jan 1 00:00:00 1970 From: Abramo Bagnara Subject: Re: Re: About integer64 Date: Thu, 09 May 2002 14:32:50 +0200 Sender: alsa-devel-admin@lists.sourceforge.net Message-ID: <3CDA6C72.42150590@alsa-project.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii 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: Jaroslav Kysela , alsa-devel@lists.sourceforge.net List-Id: alsa-devel@alsa-project.org Paul Davis wrote: > > > > >I don't think that's a bad thing to have support for 64 bit integers > >(perhaps for future use, who knows), but I think that to use this to > >store a fixed point float is a big mistake. > > > >If you think for it you realize that it's *not* an integer and > >applications are betrayed in their expectation. > > in this case, it *is* an integer. your original question was about why > its 64 bits - i think that comes from the fixed point internal > arithmetic. but the end result is a straightforward 64 bit little > endian integer that needs scaling to get the actual RMS value. You wrote: > It seems that the 64 bit-ness comes from it being some > kind of fixed point representation - the value that you read from the > registers need scaling (in user space, presumably) by a floating point > transformation to actually become true RMS values. so its not so much > they they need 64 bits of precision, more that the hardware needs to > do the math with this type of data format. keep in mind the > computation is all being done on a Xilinx FPGA, not a DSP chip, so the > arithmetic options are (at this time) a bit limited. What I'm misunderstanding? I tend to interpret the former and the latter statements in a contradictory way. -- Abramo Bagnara mailto:abramo@alsa-project.org Opera Unica Phone: +39.546.656023 Via Emilia Interna, 140 48014 Castel Bolognese (RA) - Italy ALSA project http://www.alsa-project.org It sounds good! _______________________________________________________________ Have big pipes? SourceForge.net is looking for download mirrors. We supply the hardware. You get the recognition. Email Us: bandwidth@sourceforge.net