NAME

       MPI_Compare_and_swap -  Perform one-sided atomic compare-and-swap.

SYNOPSIS

       int MPI_Compare_and_swap(const void *origin_addr, const void *compare_addr, void *result_addr,
       MPI_Datatype datatype, int target_rank, MPI_Aint target_disp, MPI_Win win)

INPUT PARAMETERS

       origin_addr
              - initial address of buffer (choice)
       compare_addr
              - initial address of compare buffer (choice)
       datatype
              - datatype of the element in all buffers (handle)
       target_rank
              - rank of target (non-negative integer)
       target_disp
              -  displacement  from  start  of window to beginning of target buffer (non-negative
              integer)
       win    - window object (handle)

OUTPUT PARAMETERS

       result_addr
              - initial address of result buffer (choice)

NOTES

       This operation is atomic with respect to other "accumulate" operations.

       The parameter datatype must belong to  one  of  the  following  categories  of  predefined
       datatypes: C integer, Fortran integer, Logical, Multi-language types, or Byte as specified
       in Section 5.9.2 on page 176. The origin and result buffers (origin_addr and  result_addr)
       must be disjoint.

NOTES FOR FORTRAN

       All  MPI  routines  in  Fortran  (except  for MPI_WTIME and MPI_WTICK ) have an additional
       argument ierr at the end of the argument list.  ierr  is  an  integer  and  has  the  same
       meaning  as  the  return  value  of  the  routine  in  C.   In  Fortran,  MPI routines are
       subroutines, and are invoked with the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

ERRORS

       All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error value;  C  routines  as
       the  value of the function and Fortran routines in the last argument.  Before the value is
       returned, the current MPI error handler is called.  By default, this error handler  aborts
       the  MPI  job.   The  error  handler  may  be  changed  with  MPI_Comm_set_errhandler (for
       communicators), MPI_File_set_errhandler (for files), and MPI_Win_set_errhandler  (for  RMA
       windows).   The  MPI-1  routine  MPI_Errhandler_set may be used but its use is deprecated.
       The predefined error handler MPI_ERRORS_RETURN may be used to cause  error  values  to  be
       returned.   Note  that  MPI  does  not  guarantee that an MPI program can continue past an
       error; however, MPI implementations will attempt to continue whenever possible.

       MPI_SUCCESS
              - No error; MPI routine completed successfully.

       MPI_ERR_ARG
              - Invalid argument.  Some argument is invalid and is not identified by  a  specific
              error class (e.g., MPI_ERR_RANK ).
       MPI_ERR_DISP
              -
       MPI_ERR_RANK
              -  Invalid  source or destination rank.  Ranks must be between zero and the size of
              the  communicator  minus  one;  ranks  in  a  receive  (  MPI_Recv  ,  MPI_Irecv  ,
              MPI_Sendrecv , etc.) may also be MPI_ANY_SOURCE .

       MPI_ERR_WIN
              - Invalid MPI window object
       MPI_ERR_OTHER
              - Other error; use MPI_Error_string to get more information about this error code.

                                            2/22/2022                     MPI_Compare_and_swap(3)