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Service_PDriverGetMessages
Programmer's Reference Manuals
» Part 16 – Service Calls
» Service_PDriverGetMessages
Service_PDriverGetMessages
(Service &78)
| Entry | |
|---|---|
| R1 | 120 (&78) |
| Exit | |
|---|---|
| R1-R3 | Preserved to pass on, else |
| R1 | 0 (claimed) |
| R3 | Pointer to block (20 bytes in size) |
Use
This service is issued when a PDriver module is about to open Resources:$.Resources.PDrivers.Messages.
Notes
If another PDriver module has already opened this file, it should claim the service and return the block pointed to by R3.
If a PDriver module issues this service and it goes unclaimed, it should allocate 20 bytes with OS_Module 6, pass the block to MessageTrans_OpenFile?, and set the last word (usage count) to 1.
If the service is claimed, then the PDriver module should increase the usage count in the block by 1.
Either way, when the PDriver module is finished with the file, it should decrease the usage count in the block by 1. If this reduces the count to 0, it should call MessageTrans_CloseFile? and then OS_Module 7 to free the block.
See also
- MessageTrans_CloseFile?
- MessageTrans_OpenFile?
- OS_Module 6
- OS_Module 7
- Service Calls
- Service_PDriverGetMessages Block