Greetings, On Sun, 14 Mar 2010 18:29:09 -0700 (PDT), mattschinkel wrote > Can someone comment on ram speed vs program data speed? > > I don't remember much about workings of microcontrollers from back in > school, but I think it needs to "switch banks" or something like that > to read program data? I have read online that the best place for it > is ram. > > As stated, a user constant could be useful. I know lookup tables > consume much data space.
Speed: a constant array lookup requires 9 clocks; a variable array lookup requires 5 clocks. Note that this assumes the variable array fits in a single bank which would not be true for a 256 entry array except on the 16 bit cores. Adding the split bank logic will require far more than 9 cycles. Memory: a constant array takes up roughly 1/2 the program memory as a variable array, and requires zero data space. Finally, this smacks of pre-mature optimization. Unless you *know* the bottleneck is in the CRC routine, it's rather silly to spend any time optimizing it. --kyle -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
