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 - Invalid displacement argument

  • 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.