Optional extensions that implement atomic operations on 64-bit signed and unsigned integers to locations in __global and __local memory.
          An application that wants to use this extension will need to include the
          #pragma OPENCL EXTENSION cl_khr_int64_base_atomics : enable
          directive in the OpenCL program source.
        
          The atomic functions supported by the cl_khr_int64_base_atomics
          extension are described in the following table. All of the functions listed in the
          following table are performed in one atomic transaction.
        
These transactions are atomic for the device executing these atomic functions. There is no guarantee of atomicity if the atomic operations to the same memory location are being performed by kernels executing on multiple devices.
Atomic operations on 64-bit integers and 32-bit integers (and float) are also atomic w.r.t. each other.
 Copyright © 2007-2013 The Khronos Group Inc. 
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Copyright © 2007-2013 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.