What is save context?
The “context saving” means the first thing an interrupt does is to save all the intermediary data (save W, PROD, tmp.), and the last operation is to restore all these data. The W register is always saved, but all the others are not. You have to tell the compiler to do it (or do it yourself).
What is context saving in embedded system?
1. 1. Automatic context saving means that the device will, upon an interrupt request, save basic registers (In a PIC > W, STATUS, BSR, FSR, PCLATH, etc) to shadow registers. When returning from the interrupt routine, these registers are automatically restored to the values they had before the ISR.
How is task context saved during interrupt?
An ISR always needs to save the “context” so that the interrupted code is unaffected by the computations of the ISR. In a system implemented without an RTOS, this is simply a matter of preserving any registers used by the ISR – generally on the stack – and restoring them before return.
Which data structure is used to save context when interrupt occurs?
This is usually stored in a data structure called a process control block (PCB) or switchframe. The PCB might be stored on a per-process stack in kernel memory (as opposed to the user-mode call stack), or there may be some specific operating system-defined data structure for this information.
What is Nsmanagedobjectcontext?
An object space to manipulate and track changes to managed objects.
What is NSFetchRequest in Swift?
An instance of NSFetchRequest collects the criteria needed to select and optionally to sort a group of managed objects held in a persistent store. An array of sort descriptors (instances of NSSortDescriptor ) that specify how the returned objects should be ordered, for example, by last name then by first name.
What happens if two interrupts occur at the same time?
When two interrupt requests are raised at the same time, and both are unmasked, a given processor can only respond to one of them.
What is the purpose of NSManagedObjectContext?
A managed object context is an instance of NSManagedObjectContext . Its primary responsibility is to manage a collection of managed objects. These managed objects represent an internally consistent view of one or more persistent stores.
Is Core Data thread safe?
Core Data is designed to work in a multithreaded environment. However, not every object under the Core Data framework is thread safe. To use Core Data in a multithreaded environment, ensure that: Managed object contexts are bound to the thread (queue) that they are associated with upon initialization.