Dear all,
its quite funny to see how we go around in circles here, this proposal of Albert
now is quite close to my original proposal. Only that I factored the ms_to_ticks
AND the comparison into the timer calls:
u64 timer_setup(u32 timeout_in_ms)
{
return get_ticks() + ms_to_ticks(timeout_in_ms);
}
int timer_expired(u64 endtime)
{
/*
* convert the unsigned difference to signed, to easyly
* check for "carry". In assembly we could just do a BCC
* after the subtraction to see whether get_ticks()
* has passed ahead of endtime.
*/
return (signed)(endtime - get_ticks()) < 0;
}
What can be more pragmatic and trivial than those two functions??
Usage then:
/* let's wait 200 milliseconds */
u64 endtime = timer_setup(200);
do {
...
} while (!timer_expired(endtime));
> That's where I come back to one point of my proposal: if we can get a
> general framework for get_timer() to return a 64-bit free-running tick
We have that already at least on PowerPC and AT91. Its called u64
get_ticks(void)
and returns a free running 64 bit value. An associated function,
u64 get_tbclk(void) returns the frequency of that tick.
I don't think that this part of the framework needs to be discussed -
except *maybe* for function names.
> value, then we might not need a ms-based get_time() at all, because we
> could use get_timer() as well for ms timings, provided we can convert
> our timeout from ms to ticks, i.e.
>
> /* let's wait 200 milliseconds */
> /* Timing loop uses ticks: convert 200 ms to 'timeout' ticks */
> timeout = ms_to_ticks(200);
> u32 start = get_timer(); /* start time, in ticks */
> do {
> ...
> } while ( (get_timer() -start) < timeout);
Mandatory u64 for start AND timeout, please.
It is the same functionality as my proposal, just bears more places where
"users" might make mistakes.
But I am sure that Wolfgang will not like either of our proposals, because
the variables used in "userspace" are not in ms.
Reinhard
_______________________________________________
U-Boot mailing list
U-Boot@lists.denx.de
http://lists.denx.de/mailman/listinfo/u-boot
