What is the spin equivalent

Greg LaPolla

In C you can do

var = ~var 

but it doesn't work in spin 2. I tried

var := !var 

and it makes 8 bits become 32 bits.

JonnyMac

! is the correct operator. Spin does not have a way to recast variable size. I tested on a byte and then output 16 bits -- the upper eight bits were 0 (hence not affected).

Greg LaPolla

here is the scenario:

lets say val = %10000000

in c val = ~val would yield %01111111

in spin2 val = !val would yield %11111111_11111111_11111111_011111111

Rayman

Is var declared as a byte in a var section ?

Greg LaPolla

No.

in PUB i initialize it as byte[@val] := $00

JonnyMac

That will only happen, Greg, when your variable is a long. As I stated earlier, Spin cannot recast variables. If you declare your variable as a byte it will stay a byte -- and remember, locals are longs unless you explicitly define them as bytes or words.

Here's a screen-shot of my test.

Greg LaPolla

I changed it to byte on the pub line. That fixed part of the problem.

val = %10000000

val = !val
now val = %1111111

here is the code

first debug in else prints out %10000000

second debug in else prints out %1111111

PUB setLed(addr, row, column, state) | byte val, offset

  val := $00

  if(addr<0 || addr>=maxDevices)
    return

  if(row<0 || row>7 || column<0 || column>7)
    return

  offset := addr * 8
  val := %10000000 >> column

  if(state)
    status[offset+row] := status[offset+row]|val
  else
    debug (ubin(val))
    val := !val
    debug ("fliped ",ubin(val))
    status[offset+row] := status[offset+row]&val

  spiTransfer(addr, row+1, status[offset+row])

Rayman

Looks like it flipped all the bits. Isn't that the right thing to do?

Greg LaPolla

It's missing a 0 at the beginning of the second debug. the value after the !val should be %01111111

Rayman

Debug may not be showing you that leading 0

Francis Bauer

Greg,

It is probably that the un-typed version of the ubin output of debug doesn't show leading zeroes to pad out a byte.

Try:

debug ("flipped ",ubin_byte(val))

to format the displayed output as a full byte.

Cluso99

@"Greg LaPolla" said:
It's missing a 0 at the beginning of the second debug. the value after the !val should be %01111111

There is an implied 0 at the beginning.
%1111111 = %01111111

cgracey

var!

That will flip all bits.