[linux-dvb] Re: User space: ioctl DMX_GET_STC values arn't 64 bit

[Johannes Stezenbach <js@convergence.de>]

Hi,

Dr. Werner Fink wrote:
>       the STC values return by the ioctl DMX_GET_STC seems not
> to be 64 bit save on a normal INTEL box.  If the PTS value of the
> current replay (played by VDR) crosses the boundary
> 
>        ~0U aka 0xffffffff aka UINT_MAX
> 
> the value of the STC is decreased by UINT_MAX.  Maybe it is not
> possible to copy a uint64_t into the users space without stripping
> a few bits.  It works as long as the PTS value is smaller than
> UINT_MAX ... if not one have to check the current PTS value and
> add UINT_MAX to STC to get correct results.
> 
> For tests without VDR you may use test_stc and a recording with
> very large PTS values.  The test_stc program returns the same
> results as the GetSTC() VDR routine.

Actually this is a limitiation of the av7110 firmware (RTSL)
and/or the hardware, which just drops the 33rd bit (msb) from
the PTS/STC. I think there isn't much we can do about it.

I think (i.e. I must test again ;) DMX_GET_STC works fine on
the MIPS based platform I'm working on.

Regards,
Johannes


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