QNX RTOS v4 Knowledge Base
QNX RTOS v4 Knowledge Base
| Title |
How to guarantee an atomic operation in QNX4 |
| Ref. No. |
QNX.000009413 |
| Category(ies) |
Development |
| Issue |
Programming in Watcom 10.6 C and QNX 4.24, I have some variables that will be shared by other processes and need to guarantee that only one process can use the variable at a time.
What can I do to insure that an operation is atomic under QNX 4.24?
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| Solution |
If your processes are going to read/write to your variables at interrupt time, there is pretty much only one method: enable()/disable() pairs.
If accesses are to be done at process time, then
a common method is to protect the critical access with semaphores -- look at sem_init(), sem_wait(), and sem_post() in the manual.
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