Question: What Does Stack Pointer Do?

What is main stack pointer?

Main Stack Pointer (MSP) is the default stack pointer.

It is used in the Thread mode when the CONTROL bit[1] (SPSEL) is 0, and it is always used in Handler mode.

Stack operations like PUSH and POP instructions, and most instructions that use SP (R13) use the currently selected stack pointer..

What is the function of stack pointer and program counter?

They are the stack pointer, SP, and the program counter, PC. The Stack Pointer register will hold the address of the top location of the stack. And the program counter is a register always it will hold the address of the memory location from where the next instruction for execution will have to be fetched.

Which register is the stack pointer?

Stack registers in x86 In 8086, the main stack register is called stack pointer – SP. The stack segment register (SS) is usually used to store information about the memory segment that stores the call stack of currently executed program. SP points to current stack top.

How do you use a stack pointer?

The Stack Pointer (SP) register is used to indicate the location of the last item put onto the stack. When you PUT something ONTO the stack (PUSH onto the stack), the SP is decremented before the item is placed on the stack.

Where are stack pointers stored?

The program instructions always store in the program counter (PC), the data registers are identified by the address register (AR). The address 3000 to 4001 used for the stack and the first item or element is stored at 4001.

Why stack pointer is 16 bit?

Thus these registers are used to store the memory locations where the Program Counter and Stack pointers point to and as we discussed earlier address of a memory location is of 16 bit, so therefore these registers are of 16 bit so that they can store the 16 bit address as data in these registers.

How values are pushed and popped from stack using stack pointer?

Whenever you push data onto the stack, the 80×86 decrements the stack pointer by the size of the data you are pushing, and then it copies the data to memory where ESP is then pointing. Therefore, the stack grows and shrinks as you push data onto the stack and pop data from the stack.

How many pointers are used in queue?

twoQueues maintain two data pointers, front and rear.

What is stack in CPU?

The stack is a list of data words. It uses Last In First Out (LIFO) access method which is the most popular access method in most of the CPU. A register is used to store the address of the topmost element of the stack which is known as Stack pointer (SP).

What is stack pointer in arm?

The stack is generally used to hold “automatic” variables and context/parameters across function calls. … You can remove data from the “top” of the “stack” and make it shorter. From the ARM architecture reference: SP, the Stack Pointer. Register R13 is used as a pointer to the active stack.

How do you initialize a stack pointer?

Example stack pointer initialization To set up the stack pointers, enter each mode with interrupts disabled, and assign the appropriate value to the stack pointer. The stack pointer value set up in the reset handler is automatically passed as a parameter to __user_initial_stackheap() by C library initialization code.

What will happen to stack pointer if we push data onto stack?

A stack pointer is a small register that stores the address of the last program request in a stack. … When a new data item is entered or “pushed” onto the top of a stack, the stack pointer increments to the next physical memory address, and the new item is copied to that address.

How many pointers are used in stack?

In programming, the stack pointer can be accessed as either R13 or SP in the program codes. Depending on the processor state and the CONTROL register value, the stack pointer accessed can either be the MSP or the PSP. In many simple applications, only one stack pointer is needed and by default the MSP is used.

What is the position of stack pointer after the pop instruction?

In POP instruction, after each execution of the instruction, the stack pointer is a) incremented by 1 b) decremented by 1 c) incremented by 2 d) decremented by 2 Answer: c Explanation: The actual current stack top is poped into the specific operand as the contents of stack top memory is stored in AL&SP and further …