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The term "segment" comes from the memory segment, which is a historical approach to memory management that has been succeeded by paging.When a program is stored in an object file, the code segment is a part of this file; when the loader places a program into memory so that it may be executed, various memory regions are allocated (in particular, as pages), corresponding to both the segments in ...
The stack segment contains the call stack, a LIFO structure, typically located in the higher parts of memory. A "stack pointer" register tracks the top of the stack; it is adjusted each time a value is "pushed" onto the stack. The set of values pushed for one function call is termed a "stack frame". A stack frame consists at minimum of a return ...
It is the fastest and most flexible cache organization that uses an associative memory. The associative memory stores both the address and content of the memory word. [further explanation needed] In the boot process of some computers, a memory map may be passed on from the firmware to instruct an operating system kernel about memory layout. It ...
This shows the typical layout of a simple computer's program memory with the text, various data, and stack and heap sections. Historically, BSS (from Block Started by Symbol) is a pseudo-operation in UA-SAP (United Aircraft Symbolic Assembly Program), the assembler developed in the mid-1950s for the IBM 704 by Roy Nutt, Walter Ramshaw, and others at United Aircraft Corporation.
Overlaying is a programming method that allows programs to be larger than the computer's main memory. [2] An embedded system would normally use overlays because of the limitation of physical memory, which is internal memory for a system-on-chip, and the lack of virtual memory facilities.
For example, within an unconditional branch instruction (X'47F0Fxxx'), the xxx 12-bit hexadecimal offset provided the byte offset from the base register (15) to branch to. An odd offset would cause a program check (unless the base register itself also contained an odd address)—since instructions had to be aligned on half-word boundaries to ...
In x86 systems, typically the BIOS / UEFI ROM is mapped to a fixed memory space upon power-on, [3] and BIOS / UEFI in x86 systems use XIP to initialize the main memory. In ARM and RISC-V embedded systems, typically the SoC built-in boot ROM is mapped to a fixed memory space upon power-on, and the boot ROM can find and load an embedded ...
[24] dlmalloc is a boundary tag allocator. Memory on the heap is allocated as "chunks", an 8-byte aligned data structure which contains a header, and usable memory. Allocated memory contains an 8- or 16-byte overhead for the size of the chunk and usage flags (similar to a dope vector). Unallocated chunks also store pointers to other free chunks ...