Hi Wolfgang,
Since discussion seems to have died down, I have assumed pseudo consensus and have started hitting the timer cleanup in earnest. All I can say is:
Wow! What a mess ;)
We could also design a more complicated API like this one, but I doubt this is needed:
Well, it is needed if you are measuring how long something has taken (say erasing a Flash, performing an I/O operation, profiling boot-up etc)
/* * round - used to control rounding: * <0 : round down, return time that has passed AT LEAST * =0 : don't round, provide raw time difference * >0 : round up, return time that has passed AT MOST */ u32 delta_timer(u32 from, u32 to, int round) {
[snip]
}
I decided to implement three separate functions:
u32 time_ms_delta_min(u32 from, u32 to) u32 time_ms_delta_max(u32 from, u32 to) u32 time_ms_delta_raw(u32 from, u32 to)
So if you only use one, the rest get stripped out of the binary
The ms_ part allows for:
u32 time_us_delta_min(u32 from, u32 to) u32 time_us_delta_max(u32 from, u32 to) u32 time_us_delta_raw(u32 from, u32 to)
I intend to let the time_us_delta* functions drop to ms resolution of the underlying tick counter is not sub-millisecond. Where the tick counter is microsecond (or better), then arch-specific udelay becomes a trivial implementation of a loop using time_us_now() and time_us_delta_min() - Actually, we can make this a weak default and have arches with a non microsecond tick counter override it.
So our timeout from case 1) above would now be written like this:
u32 start,now;u32 timeout = 5 * CONFIG_SYS_HZ; /* timeout after 5 seconds */
start = get_timer(0);
I now have: start = time_ms_now();
while (test_for_event() == 0) { now = get_timer(0);
if (delta_timer(start, now) > timeout) handle_timeout(); udelay(100);}
and would be guaranteed never to terminate early.
Comments?
With the 'time_ms_' prefix, it's starting to get rather long, and I'm pushing a lot of timeout checks beyond 80 columns - especially when existing code has variables like 'start_time_tx' - I'm starting to consider dropping the time_ prefix (all time functions will still have a ms_ or us_ prefix anyway) and rename a lot of variables
Thoughts?
Regards,
Graeme