[linux-dvb] Re: Error in vdr output format of scan

[Holger Waechtler <holger@convergence.de>]

Holger Waechtler wrote:
> Florian Steinel wrote:
>
> > Klaus Schmidinger wrote:
> >
> > > Florian Steinel wrote:
> > >  
> > > > But how avoid the use of locale eg. "S99.9E" becomes "S99,9E"?
> > > >   
> > >
> > > Take a look at VDR's cSource::ToString() in VDR/sources.c.
> > >  
> > Thank, Klaus.
> >
> > So i should use this:
> > fprintf (f, "S%u.%u%s:", orbital_pos/10, orbital_pos % 10, 
> > west_east_flag_name[we_flag]); // can't simply use "%g" here since the 
> > silly 'locale' messes up the decimal point (from vdr/sources.c)
> >
> > ok, preparing patch.
> > (is "& ~0x0800" some special mask for vdr or should i use that one too?)
>
> I suppose this expression is wiping out the sign bit and makes the 
> number always a positive one: (1 << 12)/10 == 409, the next power of 2 
> above 360 degree.
after a short look in Klaus' source I think I should be a little more exact:

The angle (Code) is specific to VDR's encoding as 12bit signed fixed 
point number:

 (Code & 0x3ff) / 10 == angle, integer part
 (Code & 0x3ff) % 10 == angle, fractional part
 Code & 0x800 == sign of angle, if this bit is set then use 'E'

Since orbital_pos in scan is always positive and the sign is encoded in 
we_flag you can safely use the construct you mentioned:

printf("%u.%u%s", orbital_pos / 10, orbital_pos % 10,
       west_east_flag_name[we_flag]);

Holger



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