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Similarly to a stack of plates, adding or removing is only practical at the top. Simple representation of a stack runtime with push and pop operations.. In computer science, a stack is an abstract data type that serves as a collection of elements with two main operations:
The stack is often used to store variables of fixed length local to the currently active functions. Programmers may further choose to explicitly use the stack to store local data of variable length. If a region of memory lies on the thread's stack, that memory is said to have been allocated on the stack, i.e. stack-based memory allocation (SBMA).
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. By default, the stack grows downward in memory, so newer values are placed at lower memory addresses. To save a value to the stack, the PUSH instruction
With a stack stored completely in RAM, this does implicit writes and reads of the in-memory stack: Load X, push to memory; Load 1, push to memory; Pop 2 values from memory, add, and push result to memory; for a total of 5 data cache references. The next step up from this is a stack machine or interpreter with a single top-of-stack register.
Provides LIFO stack interface in terms of push / pop / top operations (the last-inserted element is on top). Any sequence supporting operations back (), push_back (), and pop_back can be used to instantiate stack (e.g. vector, list, and deque). Associative containers: unordered collections set
Commonly provided are dup, to duplicate the element atop the stack, exch (or swap), to exchange elements atop the stack (the first becomes second and the second becomes first), roll, to cyclically permute elements in the stack or on part of the stack, pop (or drop), to discard the element atop the stack (push is implicit), and others. These ...
In addition, the stack pointer must always be 4-byte aligned, and must always be 8-byte aligned at a function call with a public interface. [3] This calling convention causes a "typical" ARM subroutine to: In the prologue, push r4 to r11 to the stack, and push the return address in r14 to the stack (this can be done with a single STM instruction);
In each step, it chooses a transition by indexing a table by input symbol, current state, and the symbol at the top of the stack. A pushdown automaton can also manipulate the stack, as part of performing a transition. The manipulation can be to push a particular symbol to the top of the stack, or to pop off the top of the stack.