outa and dira alias

Charlie Johnson

In PBASIC you can do:

Segs      VAR  OUTL  ' Segments on P0 - P7
SegsDIR   VAR  DIRL  ' DIRS for segments 

Is it possible to alias outa and dira?· If so, what is the syntax?

Charlie

Mike Green

No. What you appear to want is a way to name a series of I/O pins and the corresponding directions and this isn't possible in SPIN. If you don't use the special notation (outa[noparse][[/noparse]bit1..bit2]), then you can do something that probably will work by using bit masks. For example, if you have a 7 segment display on pins 3 through 9, you could write:

CON
  segMask = %1111111_000
  segShift = 3
PUB setSegments(a)
  outa := (outa & !segMask) | (a << segShift & segMask)

PUB enableSegments
  dira |= segMask  ' make segments outputs

PUB disableSegments
  dira &= !segMask  ' make segments inputs

You could get fancier by defining the highest pin # and lowest pin # and computing (as a constant) the bitmask and shift count like

CON
firstSegBit = 3
lastSegBit = 9
segMask = |<lastSegBit ^ (|<firstSegBit >> 1)  ' in other words %1111111_111 ^ %0000000_111
segShift = firstSegBit

Charlie Johnson

Mike,

Thanks for the reply. I am already using something similar to your first example. I was just curious, because I am converting all the StampWorks examples to run on the SS.

Charlie