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# docs.GL

GLSL 4
GLSL ES 3

# atomicExchange

## Name

atomicExchange — perform an atomic exchange operation to a variable

## Declaration

`int atomicExchange(` | inout int mem,
| int data`)`;

`uint atomicExchange(` | inout uint mem,
| uint data`)`;

## Parameters

`mem`

  The variable to use as the target of the operation.

`data`

  The data to be exchanged with `mem`.

## Description

`atomicExchange` performs an atomic exhange of `data` with the contents of `mem`. The content of `data` is written into `mem` and the original contents of `mem` are returned. The contents of the memory being updated by the atomic operation are guaranteed not to be modified by any other assignment or atomic memory function in any shader invocation between the time the original value is read and the time the new value is written.

Atomic memory functions are supported only for a limited set of variables. A shader will fail to compile if the value passed to the mem argument of an atomic memory function does not correspond to a buffer or shared variable. It is acceptable to pass an element of an array or a single component of a vector to the mem argument of an atomic memory function, as long as the underlying array or vector is a buffer or shared variable.

## Version Support

| OpenGL ES Shading Language Version
--- | ---
Function Name | 1.00 | 3.00 | 3.10
`atomicExchange` | - | - | ✔

## See Also

atomicAdd, atomicAnd, atomicOr, atomicXor, atomicMin, atomicMax, atomicCompSwap

## Copyright

Copyright © 2011-2014 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. https://opencontent.org/openpub/.

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