Re: [Freemint-discuss] nanoseconds delay function

[David G. <dga...@gm...>]

2018-05-18 11:29 GMT+02:00 Thorsten Otto <ad...@th...>:
> On Freitag, 18. Mai 2018 10:57:10 CEST David Gálvez wrote:
>> I've attached the patch for you to take a look in case you want to
>> comment anything.
>
> Might be cleaner to write ndelay as
>
> #define ndelay(n)  ndelay_loops(getloops4ns(n))
>

Good idea, thanks!

> Also i'm not entirely sure whether the DIV_ROUND_UP macro is used correctly
> there, you are rounding up the number of loops there? Wouldn't that give way
> too large values on slower processors?
>

The aim of these functions (mdelay, udelay and ndelay) is not to be
very very precise but give "at least" the delay requested.
On slow CPUs (for example a 030 at 16MHz) the loop count would be 0
for any given value of nanoseconds below 1000, so the loop count will
be round up to 1 to get at least the delay requested.