From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.gmx.net ([213.165.64.20]:41779 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755957AbZGNV4r (ORCPT ); Tue, 14 Jul 2009 17:56:47 -0400 Cc: linux-media@vger.kernel.org, hftom@free.fr, christophpfister@gmail.com Content-Transfer-Encoding: 7bit Content-Type: multipart/mixed; boundary="========GMX51371247608603161065" Date: Tue, 14 Jul 2009 23:56:43 +0200 From: "Hans Werner" Message-ID: <20090714215643.51370@gmx.net> MIME-Version: 1.0 Subject: AW: [BUG][PATCH] kaffeine 0.8.8 USALS/GotoX problem To: "Jesko Schwarzer" Sender: linux-media-owner@vger.kernel.org List-ID: --========GMX51371247608603161065 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit > There is a bug in DvbStream::gotoX in Kaffeine 0.8.8, which is fixed by > the > attached patch. > > Look for example at what happens when azimuth = 15.951. The motor should > be > driven to 16.0 degrees, but when 15.951 is rounded up with if (USALS>0.5) > ++rd; the carries into the upper nibble of CMD2 and the lower nibble of > CMD1 are not handled properly. The result is CMD1 represents 0 instead of > 16 > degrees and CMD2 is undefined, being set by the non-existent 11th element > of > DecimalLookup. > > The patch fixes it, and I also took the opportunity to fix the strange > division by while loops. > > Regards, > Hans -------- Original-Nachricht -------- > Datum: Tue, 14 Jul 2009 16:17:30 +0200 > Von: "Jesko Schwarzer" > An: "\'Hans Werner\'" , linux-media@vger.kernel.org > Betreff: AW: [BUG][PATCH] kaffeine 0.8.8 USALS/GotoX problem > Hello Hans, > > I looked into the patch - just to be informed what's going on and got > confused by such code. > I reimplemented it to test it against side effects and still do not > understand why it is written so complicated. Sure, I don't know the > environment of the code, but does it matter in this case ? > > If you like try these few lines (the last 3 lines) as a replacement: > > unsigned long USALS; > int CMD1; > int CMD2; > > if ( azimuth>0.0 ) > CMD1 = 0xE0; // East > else > CMD1 = 0xD0; // West > > /*-----------------------------------------------*/ > USALS = ( fabs( azimuth ) * 16.0 + 0.5 ); > CMD1 |= ( USALS & 0xf00 ) >> 8; > CMD2 = ( USALS & 0x0ff ); > /*-----------------------------------------------*/ > > Regards > /Jesko Hi Jesko, thanks for looking at it. I see the main difference in your version is that there is no DecimalLookup for the bottom 4 bits. I took a look at the Eutelsat specs here: http://www.eutelsat.com/satellites/pdf/Diseqc/associated%20docs/positioner_appli_notice.pdf The relevant section is 3.10. Reading that I see that the lower four bits should never have been coded with DecimalLookup at all !! The 12-bit value should be a true binary fraction (not any coded form of decimal) representing the angle to a precision of 1/16th of a degree. Whoever originally wrote the routine may have misinterpreted Table 2 which shows a lookup table converting the lower 4 bits of CMD2 to decimal, just for people who want to make STB displays and data entry limited to just 0.1 degree accuracy. So I think your version of the routine is correct. Mine differs sometimes by 1/16th of a degree (not perceptible with my equipment), and is the same otherwise. I have attached a new version of the patch. I compiled and tested with my rotor and confirmed it works. Regards, Hans -- Release early, release often. Jetzt kostenlos herunterladen: Internet Explorer 8 und Mozilla Firefox 3 - sicherer, schneller und einfacher! http://portal.gmx.net/de/go/atbrowser --========GMX51371247608603161065 Content-Type: text/x-patch; charset="iso-8859-15"; name="usals_bug_fix2.diff" Content-Transfer-Encoding: 8bit Content-Disposition: attachment; filename="usals_bug_fix2.diff" --- dvbstream.cpp.orig +++ dvbstream.cpp @@ -758,31 +758,20 @@ void DvbStream::gotoX( double azimuth ) { - double USALS=0.0; + unsigned long USALS; int CMD1=0x00, CMD2=0x00; - int DecimalLookup[10] = { 0x00, 0x02, 0x03, 0x05, 0x06, 0x08, 0x0A, 0x0B, 0x0D, 0x0E }; + //rotation direction if ( azimuth>0.0 ) CMD1 = 0xE0; // East else CMD1 = 0xD0; // West - USALS = fabs( azimuth ); - - while (USALS > 16) { - CMD1++; - USALS-= 16; - } - while (USALS >= 1.0) { - CMD2+=0x10; - USALS--; - } - USALS*= 10.0; - int rd = (int)USALS; - USALS-= rd; - if ( USALS>0.5 ) - ++rd; - CMD2+= DecimalLookup[rd]; + //angle : 12 bits with a precision of 1/16th of a degree + //a true binary fraction, NOT binary coded decimal + USALS = ( fabs(azimuth)*16 + 0.5 ); + CMD1 |= (USALS & 0xf00) >> 8; + CMD2 = (USALS & 0x0ff); rotorCommand( 12, CMD1, CMD2 ); } --========GMX51371247608603161065--