Offload Modes mechanism

Offload modes works as follows:

1. The AOS maintains a vector variable (aos.side[].adsec.oflmodes) which contains 22 components of modal error. The subprocess (PSF) whose task is to offload modes, can simply proceed by polling this variable and offload modes as soon as they grow up. More flexibility in the mechanism can be achieved as follows:

2. AOS maintains an integer vector variable (aos.side[].adsec.offload) again with 22 components. Each component may have value 0,1,2. Values greather than 0 indicate how urgent is the offload: 1: pretty urgent, 2: do it now!

Again PSF can poll this variable and act accordingly.

If polling is not desirable, the following step is available:

3. Whenever any element of vector aos.side[].adsec.offload changes value from 0 to >0, a command defined by PSF is issued by AOS.

On receiving the command, PSF may decide what to do by reading the two vectors described above.

Warning: This mechanism is all important when doing AO observation because it's the only way to correct for drifts in telescope tracking.