It’s always good to be cognizant of trace lengths when you’re laying out a parallel bus, though at moderate frequencies it is nothing to stress about. The propagation time for a signal traveling through a trace is maybe 150 picoseconds/inch. So if you have two traces with a length mismatch of one inch, one signal will arrive 150 ps after the other signal. If your signals are transitioning at a frequency whose corresponding period is much greater than 150 ps, this one-inch mismatch won’t cause problems. Even at 100 MHz (which is pretty fast for a parallel bus), the period is 10 ns, i.e., ~67 times larger than the time-of-arrival discrepancy for a one-inch mismatch.
In a demanding application, we may not have the time to continuously check the pointers to see if they have reached the end of the buffer and wrap them back to the beginning of the buffer when necessary. As a result, a DSP processor uses dedicated hardware to provide some fast circular buffers.This hardware implementation automatically checks the status of the pointers and updates them accordingly.
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