An interrupt is generated when the frame number rolls over and we use this to increment the upper bits so the frame number can grow beyond 11 bits. This allows software consuming the frame number not to worry about the frame wrap when scheduling isochronous I/O.
Yes, time *at* which… —scott > On Jan 5, 2017, at 9:35 PM, Guy Harris <g...@alum.mit.edu> wrote: > >> On Jan 5, 2017, at 8:42 PM, Scott Deandrea <sdeand...@apple.com> wrote: >> >> The frameNumber is a USB spec defined value that correlates with the >> start-of-frame packets frame number as defined in section 8.4.3 >> Start-of-Frame Packets. > > So only 11 of the 64 bits are used? > >> The ioTimestamp is in the same Mach Absolute Time. > > So that's "Time *at* which the frame completed", rather than "Time *in* > which..."? > _______________________________________________ tcpdump-workers mailing list tcpdump-workers@lists.tcpdump.org https://lists.sandelman.ca/mailman/listinfo/tcpdump-workers
