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A typical stack, storing local data and call information for nested procedure calls (not necessarily nested procedures). This stack grows downward from its origin. The stack pointer points to the current topmost datum on the stack. A push operation decrements the pointer and copies the data to the stack; a pop operation copies data from the ...
In computer science, an in-tree or parent pointer tree is an N-ary tree data structure in which each node has a pointer to its parent node, but no pointers to child nodes. When used to implement a set of stacks , the structure is called a spaghetti stack , cactus stack or saguaro stack (after the saguaro , a kind of cactus). [ 1 ]
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. By default, the stack grows downward in memory, so newer values are placed at lower memory addresses.
Typical examples of pointers are start pointers, end pointers, and stack pointers. These pointers can either be absolute (the actual physical address or a virtual address in virtual memory ) or relative (an offset from an absolute start address ("base") that typically uses fewer bits than a full address, but will usually require one additional ...
Default frame pointer. (R8-R13 may also serve as frame pointer and leaf routines may use R1–R3 as frame pointer.) Preserved. Frame Pointer, FP, callee saves: Variables/temporary. Guaranteed. R15: Serves as stack pointer or as a permanent register. Preserved. Stack Pointer, SP, callee saves: Stack pointer. Guaranteed.
Pointer formats are known as near, far, or huge. Near pointers are 16-bit offsets within the reference segment, i.e. DS for data and CS for code. They are the fastest pointers, but are limited to point to 64 KB of memory (to the associated segment of the data type). Near pointers can be held in registers (typically SI and DI).
If a pop operation on the stack causes the stack pointer to move past the origin of the stack, a stack underflow occurs. If a push operation causes the stack pointer to increment or decrement beyond the maximum extent of the stack, a stack overflow occurs. Some environments that rely heavily on stacks may provide additional operations, for example:
In C++, a class can overload all of the pointer operations, so an iterator can be implemented that acts more or less like a pointer, complete with dereference, increment, and decrement. This has the advantage that C++ algorithms such as std::sort can immediately be applied to plain old memory buffers, and that there is no new syntax to learn ...