Stack pointer points to the topmost / most recently referenced location on the stack;
- Nutan
If your stack grows bottom-up, it's decremented when you leave a function; if the stack grows top-down, the stack pointer is incremented.
The stack pointer is typically incremented to manage the stack's memory allocation during function calls and local variable storage. When a function is called, the stack pointer moves to allocate space for local variables and return addresses, effectively growing the stack downwards in memory. Incrementing the stack pointer helps maintain the correct position for accessing these variables and managing function calls efficiently. This process is crucial for maintaining the integrity of the stack structure and ensuring proper memory management.
Its not a stack counter - its a stack pointer. The stack pointer is a register that points to the top of the stack. In the Intel configuration, it points to the next item to be popped off the stack. To push an item requires that the stack pointer be decremented first, and then the item is written. The inverse operation - the pop - requires read then increment.
top pointer of a stack is the pointer that refers to the top most element of the stack.
Its main use is to store local variables, arguments and return address each time a function is called.When your program calls a function the following happen :- The function arguments are put on the stack- The current instruction pointer is put on the stack- The program jumps to the start of the function- Space is allocated on the stack to hold local variables- The function executes- The space holding local variables is de-allocated- The instruction pointer is restored and removed from the stack (we are now leaving the function and resuming the calling procedure)- The arguments are removed from the stack
A stack is a data structure in which last item inserted is taken out first . That's why they are known as LIFO (last in first out). Inserting an item in stack is termed as push and taking an item out from stack I s termed as pop. Stack pointer is the pointer that points to the top of the stack or that points the item at the top of the stack and help in adding or deleting the item from the top of stack.
The stack pointer is a special-purpose register in the CPU that holds the address of the top of the current stack in memory. The stack is a data structure used for managing function calls, local variables, and control flow, operating in a last-in, first-out (LIFO) manner. As functions are called and return, the stack pointer is updated to reflect the current position of the stack, ensuring proper access to function parameters and local data. This mechanism is crucial for maintaining the execution context during program runtime.
A stack pointer is a register pointing to the top of a stack. It supports the fundamental stack manipulations (push and pop) in an efficient manner. Most micro processor hardware has build-in hardware support for stack pointers, typically both in form of dedicated stack pointer registers and in form of addressing modes which support the creation and maintenance of stacks through general-purpose pointer registers. In software, many programming languages feature constructs suited for implementation of stack pointers within the high-level language (such as post-increment and pre-decrement operators in C).
Actually, stack data starts one location greater than the stack pointer. In the Intel design, the stack pointer always points to the next location to be used on a push, and pushes always decrement the pointer. It is more correct to say that the stack region to be used next is one location less than the stack pointer's register address.
Accessing a stack.
Call-stacks are fixed-length and are allocated on a per-thread basis as threads are instantiated. The stack pointer CPU register keeps track of the next available address in the current thread's stack. The compiler computes the length of a function according to the number and type of its local variables (including formal arguments) plus the return address. When the function is invoked, the current stack pointer is adjusted by this amount, creating a "stack frame" specific to that function. Given the start address of the stack frame, the local variables and formal arguments can be referred to via constant offsets within the stack frame. When the function returns, the stack pointer is readjusted, effectively freeing the memory without actually releasing it back to the system. In this way, memory can be allocated and released on the stack with minimum cost.
Because the stack pointer marks the top of the stack. If it is not initialised, it is not possible to determine where the next stack frame will go.