oek wrote on Thursday, October 06, 2011:
Hi there,
I have a small chunk of code below that needs to be atomic and may be called from ISR or task.
Variable bool bFromIsr is true if the section is called from ISR false if from task.
Two questions:
1. Is there any OS variable I can examine to know if I am presently in an ISR? (E.g. is ISR nesting level tracked somewhere, I could not find it.) Or do I have to independently provide a value for bFromIsr?
2. Have I chosen the correct macros to do this? I had thought that I should not have to call directly any functions prefixed by “port…”. What is the correct macro for “suspend interrupts from an interrupt”?
Thanks and regards,
Owen
//because this can be called indirectly from multiple tasks or ISRs the action needs to be atomic
if (bFromIsr) {
uxSavedInterruptStatus = portSET_INTERRUPT_MASK_FROM_ISR();
} else {
taskENTER_CRITICAL();
}
// BEGIN section of atomic code ////////////////
//check and update the high water mark
if (i>logPoolHwm)
{
//since we start scanning from zero, i represents the hwm
logPoolHwm = i;
}
//mark it as in use
logPool[i].inUse = 1;
// END section of atomic code ////////////////
if (bFromIsr) {
portCLEAR_INTERRUPT_MASK_FROM_ISR( uxSavedInterruptStatus );
} else {
taskEXIT_CRITICAL();
}