Apparatus and method for semaphore initialization in a multiprocessing computer system for process synchronization
US4316245A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 7, 1978 |
| Grant date | Feb 16, 1982 |
| Priority date | — |
| Expiry date | Dec 7, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/52
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Apparatus in a data processing system to initialize a semaphore held in a memory field of the data processing system or, alternatively, to restore the semaphore to a previous predetermined state. A count field, or tally field, provided in the semaphore is initialized by a particular instruction. The semaphore can be either a non-message semaphore or a message semaphore. The instruction initializes the semaphore count field of a non message semaphore to zero or a preloaded positive value. For a message semaphore, this instruction initializes the count field to zero. If the message semaphore previously had a positive count, the messages tied to the semaphore are released and the message links holding the messages are transferred to a free message link queue tied to the free link semaphore in the same semaphore descriptor segment. The apparatus includes a retrieving member for reading the content of the semaphore in the memory of the data processing system, a testing member for testing the count field of the semaphore for generating a first signal when the count field represents the number of processes in queue and a second signal when the count field represents the number of times a …
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