Table of Contents
What is the use of a function pointer?
Function pointers can be useful when you want to create callback mechanism, and need to pass address of a function to another function. They can also be useful when you want to store an array of functions, to call dynamically for example.
What is the function of interrupt keyword?
The interrupt keyword tells the compiler to generate register-saving instructions before the body of the function is executed and to restore the registers just before the ISRs return.
How could interrupts be handled?
The software assigns each interrupt to a handler in the interrupt table. An interrupt handler is just a routine containing a sequence of operations. Each of these may request input and output while running. Thus, an interrupt can be handled either as a thread or as a sub-process within a task or process.
What is the use of function pointers in C++?
It is basically used to store the address of a function. We can call the function by using the function pointer, or we can also pass the pointer to another function as a parameter. They are mainly useful for event-driven applications, callbacks, and even for storing the functions in arrays.
What is function pointer and its advantages?
1) Unlike normal pointers, a function pointer points to code, not data. Typically a function pointer stores the start of executable code. 2) Unlike normal pointers, we do not allocate de-allocate memory using function pointers. 3) A function’s name can also be used to get functions’ address.
Is function call an interrupt?
A function call is usually program generated. An interrupt is usually generated by hardware.
What are the data structures used to obtain the interrupt handler of an interrupt?
shows that irq_action is a vector of pointers to the irqaction data structure. Each irqaction data structure contains information about the handler for this interrupt, including the address of the interrupt handling routine.
Which instruction is used to store interrupts?
For a hardware interrupt, its interrupt vector number is provided by the hardware device or PIC. For a software interrupt, its interrupt vector number is provided by the int instruction. For an internal interrupt, its interrupt vector number is fixed and is known by the processor.
What are function pointers used for in C programming?
One common usage of function pointers in C is found in embedded software for handling interrupts. The interrupt handler needs to call a specific function for any given interrupt. This involves programming the interrupt controller with the address of that function.
Why use a function pointer instead of an if-else?
Instead of populating and cluttering your code with if-else constructs testing variables, you can code it so that it uses a function pointer, and then you can enable/disable features by changing/assigning the function pointer.
Can I change the function that is executed by an interrupt?
Having an API that can be called to change the function that is executed by the interrupt may seem dangerous or could be a security vulnerability. An alternative to having an API assignment is to instead use a configuration table to initialize the function pointer at compile time. You’ll notice that the Uart_Init function has the form:
How does the interrupt service routine handle the I/O pin?
The Interrupt Service Routine will handle the changing of the I/O pin. The function pointer allows the main.c file to define and contain the Interrupt Service Routine (ISR). To establish this, a function prototype declaration must be placed near the top of the main.c. In this example the function prototype is called TimerISR.