Hi Uwe, On Fri, Dec 04, 2020 at 10:55:25PM +0100, Uwe Kleine-König wrote: > On Fri, Dec 04, 2020 at 11:40:36AM +0000, Sean Young wrote: > > On Fri, Dec 04, 2020 at 12:21:15PM +0100, Uwe Kleine-König wrote: > > > On Fri, Dec 04, 2020 at 12:42:15AM +0100, Lino Sanfilippo wrote: > > > > On 29.11.20 at 19:10, Uwe Kleine-König wrote: > > > > > You're storing an unsigned long long (i.e. 64 bits) in an u32. If > > > > > you are sure that this won't discard relevant bits, please explain > > > > > this in a comment for the cursory reader. > > > > > > > > What about an extra check then to make sure that the period has not > > > > been truncated, > > > > e.g: > > > > > > > > value = DIV_ROUND_CLOSEST_ULL(state->period, scaler); > > > > > > > > /* dont accept a period that is too small or has been truncated > > > > */ > > > > if ((value < PERIOD_MIN) || > > > > (value != DIV_ROUND_CLOSEST_ULL(state->period, scaler))) > > > > return -EINVAL; > > > > > > I'd make value an unsigned long long and check for > 0xffffffff instead > > > of repeating the (expensive) division. (Hmm, maybe the compiler is smart > > > enough to not actually repeat it, but still.) > > > > I wonder where you got that idea from. > > I don't know how to honestly answer your question. > Which idea do you mean? That divisions are expensive? Or that compilers > might be smart? And do you consider it a good idea? Or do you disagree?
I had already made this exact suggestion -- and you had replied to my email making that suggestion -- before you emailed this. Granted, I said u64 and U32_MAX rather than unsigned long long and 0xffffffff. However, I should not have sent that snotty email. It's irrelevant. My apologies. Sean
