| Message ID | 20090713232043.315370@gmx.net (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
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 -----Ursprüngliche Nachricht----- Von: linux-media-owner@vger.kernel.org [mailto:linux-media-owner@vger.kernel.org] Im Auftrag von Hans Werner Gesendet: Dienstag, 14. Juli 2009 01:21 An: linux-media@vger.kernel.org Betreff: [BUG][PATCH] kaffeine 0.8.8 USALS/GotoX problem 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 -- GRATIS für alle GMX-Mitglieder: Die maxdome Movie-FLAT! Jetzt freischalten unter http://portal.gmx.net/de/go/maxdome01 -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
--- dvbstream.cpp.orig +++ dvbstream.cpp @@ -758,30 +758,26 @@ void DvbStream::gotoX( double azimuth ) { - double USALS=0.0; + int USALS; int CMD1=0x00, CMD2=0x00; int DecimalLookup[10] = { 0x00, 0x02, 0x03, 0x05, 0x06, 0x08, 0x0A, 0x0B, 0x0D, 0x0E }; + //high nibble of CMD1 if ( azimuth>0.0 ) CMD1 = 0xE0; // East else CMD1 = 0xD0; // West - USALS = fabs( azimuth ); + USALS = ( fabs(azimuth)*10 + 0.5 ); // NB tenths of a degree - 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; + //low nibble of CMD1 : 16 degree steps + CMD1+=USALS/160; + + //high nibble of CMD2 : 1 degree steps + CMD2=((USALS%160)/10)*0x10; + + //low nibble of CMD2: 0.1 degree steps, coded as in DecimalLookup + int rd = USALS%10; CMD2+= DecimalLookup[rd]; rotorCommand( 12, CMD1, CMD2 );