mp_alltoall_z22 Subroutine

      SUBROUTINE mp_alltoall_z22(sb, rb, count, group)
      !! All-to-all data exchange, rank-2 arrays, equal sizes
      !! @note see mp_alltoall_z

         COMPLEX(kind=real_8), CONTIGUOUS, INTENT(IN)        :: sb(:, :)
         COMPLEX(kind=real_8), CONTIGUOUS, INTENT(OUT)       :: rb(:, :)
         INTEGER, INTENT(IN)                      :: count
         TYPE(mp_comm_type), INTENT(IN)           :: group

         CHARACTER(LEN=*), PARAMETER :: routineN = 'mp_alltoall_z22'

         INTEGER                                  :: handle, ierr
#if defined(__parallel)
         INTEGER                                  :: msglen, np
#endif

         ierr = 0
         CALL timeset(routineN, handle)

#if defined(__parallel)
         CALL mpi_alltoall(sb, count, MPI_DOUBLE_COMPLEX, &
                           rb, count, MPI_DOUBLE_COMPLEX, group%handle, ierr)
         IF (ierr /= 0) CALL mp_stop(ierr, "mpi_alltoall @ "//routineN)
         CALL mpi_comm_size(group%handle, np, ierr)
         IF (ierr /= 0) CALL mp_stop(ierr, "mpi_comm_size @ "//routineN)
         msglen = 2*SIZE(sb)*np
         CALL add_perf(perf_id=6, msg_size=msglen*(2*real_8_size))
#else
         MARK_USED(count)
         MARK_USED(group)
         rb = sb
#endif
         CALL timestop(handle)

      END SUBROUTINE mp_alltoall_z22