MT_PRIOR/SMS_SPJB
Set a job's priority.
| Call Parameters | Return Parameters | ||
|---|---|---|---|
| D0.B | $0B | D0.L | Error code. |
| D1.L | Id of the job to be prioritised. | D1.L | Preserved unless on entry it was -1 in which case it will become the Id of the current job. |
| D2.B | Job's new priority. See notes below. | D2.L | Preserved. |
| A0.L | Unused. | A0.L | Base address of prioritised job. |
Errors
| ERR_NJ | Invalid job id. |
Notes
- All registers not shown above are not used on entry and are preserved on exit.
- The priority passed in D2.B is documented as being in the range 0 to 127, however, it appears that values from 0 to 255 can be used.
- This trap always exits via the job scheduler, so it is not atomic.
- Note to self. Check D3.W. Should there not be a timeout on this trap call? My notes say is D3.W unused on entry and D3.L is preserved on exit. Doesn't seem right.
Example
The following shows the use of this call to change the priority of the current job to a very low priority.
moveq #mt_prior,d0 ; Trap code
moveq #-1,d1 ; Change my own priority
moveq #1,d2 ; Set priority very low
trap #1 ; Change the priority
george.gwilt