Atomic_cmpxchg functions.
int atomic_cmpxchg(volatile global(3clc) int *p, int cmp, int val); unsigned int atomic_cmpxchg(volatile global(3clc) unsigned int *p, unsigned int cmp, unsigned int val); int atomic_cmpxchg(volatile local(3clc) int *p, int cmp, int val); unsigned int atomic_cmpxchg(volatile local(3clc) unsigned int *p, unsigned int cmp, unsigned int val);
Read the 32-bit value (referred to as old) stored at location pointed by p. Compute (old == cmp) ? val : old and store result at location pointed by p. The function returns old.
A 64-bit version of this function, atom_cmpxchg(3clc), is enabled by cl_khr_int64_base_atomics(3clc).
\m[blue]OpenCL Specification\m[]\s-2\u[1]\d\s+2
atomicFunctions(3clc), atom_cmpxchg(3clc)
The Khronos Group
Copyright © 2007-2011 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and/or associated documentation files (the "Materials"), to deal in the Materials without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Materials, and to permit persons to whom the Materials are furnished to do so, subject to the condition that this copyright notice and permission notice shall be included in all copies or substantial portions of the Materials.
OpenCL Specification
page 279, section 6.12.11 - Atomic Functions for 32-bit integers