[vlc-devel] [PATCH 04/10] vlc_tick: add helper function for explicit nanosecond to/from vlc_tick_t conversion

[Steve Lhomme]

On 2018-06-22 3:27 PM, Romain Vimont wrote:
> On Fri, Jun 22, 2018 at 02:53:21PM +0200, Steve Lhomme wrote:
>> ---
>>   include/vlc_tick.h | 10 ++++++++++
>>   1 file changed, 10 insertions(+)
>>
>> diff --git a/include/vlc_tick.h b/include/vlc_tick.h
>> index 66cf8ecf687..bf037087510 100644
>> --- a/include/vlc_tick.h
>> +++ b/include/vlc_tick.h
>> @@ -73,6 +73,16 @@ static inline int64_t ms_from_vlc_tick(vlc_tick_t vtk)
>>       return vtk / (CLOCK_FREQ / 1000);
>>   }
>>   
>> +static inline vlc_tick_t vlc_tick_from_ns(int64_t nano)
>> +{
>> +    return nano / (INT64_C(1000000000) / CLOCK_FREQ);
>> +}
>> +
>> +static inline int64_t ns_from_vlc_tick(vlc_tick_t vtk)
>> +{
>> +    return vtk * INT64_C(1000000000) / CLOCK_FREQ;
> Should compute division first, to avoid overflow (UB) if vtk > 2^64/10^9

You mean INT64_C(1000000000) / CLOCK_FREQ or vtk / CLOCK_FREQ ? (I 
suppose the former)
> ticks, which is about 5 hours.
>
>> +}
>> +
>>   /*****************************************************************************
>>    * MSTRTIME_MAX_SIZE: maximum possible size of mstrtime
>>    *****************************************************************************
>> -- 
>> 2.17.0
>>
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