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In a computer using virtual memory, accessing the location corresponding to a memory address may involve many levels. In computing, a memory address is a reference to a specific memory location in memory used by both software and hardware. [1] These addresses are fixed-length sequences of digits, typically displayed and handled as unsigned ...
Another example in the same computer family was the 16-bit protected mode of the 80286 processor, which, though supporting only 16 MB of physical memory, could access up to 1 GB of virtual memory, but the combination of 16-bit address and segment registers made accessing more than 64 KB in one data structure cumbersome.
The dynamic loader calculates the address referred to by a global variable and stores the value in such global variable; this triggers copy-on-write of a memory page containing such global variable. Pages with code and pages with global variables that do not contain pointers to code or global data remain shared between processes.
A memory address a is said to be n-byte aligned when a is a multiple of n (where n is a power of 2). In this context, a byte is the smallest unit of memory access, i.e. each memory address specifies a different byte. An n-byte aligned address would have a minimum of log 2 (n) least-significant zeros when expressed in binary.
Each segment was placed at a specific location in memory by the software being executed and all instructions that operated on the data within those segments were performed relative to the start of that segment. This allowed a 16-bit address register, which would normally be able to access 64 KB of memory space, to access 1 MB of memory space.
Note that this is more or less the same as base-plus-offset addressing mode, except that the offset in this case is large enough to address any memory location. Example 1: Within a subroutine, a programmer may define a string as a local constant or a static variable. The address of the string is stored in the literal address in the instruction.
The TlsGetValue and TlsSetValue functions are then used to read and write a memory address to a thread-local variable identified by the TLS slot index. TlsSetValue only affects the variable for the current thread. The TlsFree function can be called to release the TLS slot index. There is a Win32 Thread Information Block for each thread.
This guarantees the order of the two addition operations, but potentially introduces a new problem of address aliasing: any of these pointers could potentially refer to the same memory location. For example, let's assume in this example that *c and *sum are aliased to the same memory location, and rewrite both versions of the program with *sum ...