Hi Simon, On Thu, Jun 16, 2011 at 3:53 PM, Simon Glass <s...@chromium.org> wrote: > Hi Graeme, > > On Wed, Jun 15, 2011 at 4:09 PM, Graeme Russ <graeme.r...@gmail.com> wrote: > [snip] >>> >>> BTW should the deltas return a signed value? >> >> No - times are unsigned utilising the entire range of the u32 so (to - >> from) will always returned the unsigned delta, even if there is a wrap >> between them. I cannot imagine we would ever need to measure time backward >> anyway. > > Can you please explain this again in different words as I don't > follow. The difference between two unsigned times may be +ve or -ve, > surely. For example, say: > > now = 100 > event_time = 200 > > then the delta is currently -100. Some people might loop until the > delta is >= 0. This is like setting a future time and waiting for it > to happen. If the delta is unsigned then this won't work. >
start = 0xffffff00 now = 0x00000010 So there was a timer wrap between 'start' and 'now' delta = now - start = 0x110 Remember that the new timer API does not rely on the tick counter (and therefore the ms/us timers) to start at zero - It must be allowed to wrap without causing timer glitches at any arbitray time Regards, Graeme _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
