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