Search results
Results From The WOW.Com Content Network
The Standard Template Library overloads its built-in swap function to exchange the contents of containers efficiently this way. [ 1 ] As pointer variables are usually of a fixed size (e.g., most desktop computers have pointers 64 bits long), and they are numeric, they can be swapped quickly using XOR swap .
In the C++ Standard Library, several algorithms use unqualified calls to swap from within the std namespace. As a result, the generic std::swap function is used if nothing else is found, but if these algorithms are used with a third-party class, Foo, found in another namespace that also contains swap(Foo&, Foo&), that overload of swap will be used.
Many C compilers support using compare-and-swap either with the C11 <stdatomic.h> functions, [8] or some non-standard C extension of that particular C compiler, [9] or by calling a function written directly in assembly language using the compare-and-swap instruction. The following C function shows the basic behavior of a compare-and-swap ...
Using the XOR swap algorithm to exchange nibbles between variables without the use of temporary storage. In computer programming, the exclusive or swap (sometimes shortened to XOR swap) is an algorithm that uses the exclusive or bitwise operation to swap the values of two variables without using the temporary variable which is normally required.
Those that do not can still implement an atomic test-and-set using a read-modify-write or compare-and-swap instruction. The test and set instruction, when used with boolean values, uses logic like that shown in the following function, except that the function must execute atomically. That is, no other process must be able to interrupt the ...
This is an example swap function that fails to be reentrant or thread-safe. Since the tmp variable is globally shared, without synchronization, among any concurrent instances of the function, one instance may interfere with the data relied upon by another.
C++ vectors do not support in-place reallocation of memory, by design; i.e., upon reallocation of a vector, the memory it held will always be copied to a new block of memory using its elements' copy constructor, and then released.
The function makecontext requires additional parameters to be type int, but the example passes pointers. Thus, the example may fail on 64-bit machines (specifically LP64-architectures, where sizeof (void *) > sizeof (int)). This problem can be worked around by breaking up and reconstructing 64-bit values, but that introduces a performance penalty.