Change Endianness of a Word in SPIN2

ke4pjw

Is there a way to change the endianness of a WORD in SPIN2?
I do not believe that a ROR= 8 will work, because I suspect it would shift though the adjacent WORD.

Should I just load the information into a LONG, perform the appropriate ROR and forget about trying to save memory?

Wuerfel_21

No such thing happens - all values are computed in 32 bit, if you have a word variable, that just means that it only stores the bottom half of values stored into it.

But just RORing is not what you want in such a case. What you want is some equivalent of the MOVBYTS instruction. Inexplicably, that doesn't exist, so you need to create a local variable and do something like

org
movbyts value,#%%3201 ' word-size endian swap
end

Flexspin also has an intrinsic: value := __builtin_bswap16(value)

ChrisGadd

Works fine if you combine a rol and ror:

value := value rol 8 | value ror 8

ke4pjw

@ChrisGadd said:
Works fine if you combine a rol and ror:

value := value rol 8 | value ror 8

That worked well. Would be nice if there was a hub version of movbyts or and spin2 equivalent.

JonnyMac

That worked well. Would be nice if there was a hub version of movbyts or and spin2 equivalent.

I'd like that, too. Until it happens (how about it, @cgracey?) you can encapsulate it in a method (assuming you're not compiling Spin2 [where I think you can just do it inline])

pub move_bytes(value, arrangment) : result

  org
                        mov       result, value
                        movbyts   result, arrangment
  end