System.AtomicExchange

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Object Pascal

function AtomicExchange(var Target; Value: <Integer or NativeInt or Pointer>): Integer; overload;
function AtomicExchange(var Target; Value: <Integer or NativeInt or Pointer>): Int64; overload;
function AtomicExchange(var Target; Value: <Integer or NativeInt or Pointer>): Pointer; overload;
function AtomicExchange(var Target; Value: <Integer or NativeInt or Pointer>): NativeInt; overload;

Properties

Type Visibility Source Unit Parent
function public System.pas System System

Description

Atomic intrinsic Exchange function for use with Object Pascal mobile compilers. Writes the given value to the target and returns the previous value of the target.

Because the Object Pascal mobile compilers do not support a built-in assembler, the System unit provides four atomic intrinsic functions that provide a way to atomically exchange, compare and exchange, increment, and decrement memory values.

AtomicExchange is used for exchanging memory values.

Atomic operations are used to:

  • Implement multi-threaded locking primitives
  • Provide the primitives necessary for implementing so-called "lock-free" structures

See Also