Fix gpart id/pointer
Making a union of the
gpart ID and the part pointer seemed like a good idea at first, but it's just an accident waiting to happen, as the pointers are not guaranteed to be less than 2^63. I therefore suggest the following:
- Store the
gpartID as a
- If the
gpartID is positive, it's just the particle's ID.
- If the
gpartID is negative, then it is the negative offset in the
space->partsarray of its
This storage format has the additional advantage that it makes it easier to re-link the particles if we ever do have to send them around between nodes, e.g. by making the offsets relative to whatever array the data is stored/sent in.
This is currently just a proposal. Please let me know what you think and if there is no opposition I will change this as soon as the initial
gpart branch has been merged (!116 (merged)).