John Goerzen ha scritto:
Steve Schafer wrote:
On Fri, 09 Jan 2009 11:01:18 -0200, you wrote:
I'm writing a program that will read medical signs from many patients. It's important to have a precise measure of the time interval between some signs, and that can't depend on adjustments of time. (Supose my software is running midnight at the end of a year with leap seconds. I would get wrong time intervals.) If you really need that level of accuracy, there is nothing available on an off-the-shelf machine that will do the job. You need an independent timekeeping source of some kind, one that is not subject to the vagaries
I'm not sure that the original question implied *that* level of need.
Linux has High-Resolution Timers (HRTs) that may be appropriate. See the manpage for clock_gettime(), which defines these HRTs:
[...]
CLOCK_MONOTONIC, in particular, looks suitable. Using it could be a matter of just a few quick likes in FFI.
There is also an available package on Hackage: posix-realtime.
I don't know if Windows has similar features.
http://msdn.microsoft.com/en-us/library/ms632592(VS.85).aspx and QueryPerformanceCounter, in detail. Unfortunately, documentation is really bad, and it is not really clear what "high-resolution performance counter" means.
-- John
Manlio Perillo