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MPI_Alloc_mem.3.rst

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MPI_Alloc_mem

:ref:`MPI_Alloc_mem` |mdash| Allocates a specified memory segment.

SYNTAX

C Syntax

#include <mpi.h>

int MPI_Alloc_mem(MPI_Aint size, MPI_Info info, void *baseptr)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_ALLOC_MEM(SIZE, INFO, BASEPTR, IERROR)
     INTEGER INFO, IERROR
     INTEGER(KIND=MPI_ADDRESS_KIND) SIZE, BASEPTR

Fortran 2008 Syntax

USE mpi_f08
MPI_Alloc_mem(size, info, baseptr, ierror)
     USE, INTRINSIC :: ISO_C_BINDING, ONLY
     INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) :: size
     TYPE(MPI_Info), INTENT(IN) :: info
     TYPE(C_PTR), INTENT(OUT) :: baseptr
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS

  • size: Size of memory segment in bytes (nonnegative integer).
  • info: Info argument (handle).

OUTPUT PARAMETERS

  • baseptr: Pointer to beginning of memory segment allocated.
  • ierror: Fortran only: Error status (integer).

DESCRIPTION

:ref:`MPI_Alloc_mem` allocates size bytes of memory. The starting address of this memory is returned in the variable baseptr.

C NOTES

The parameter baseptr is of type void * to allow passing any pointer object for this parameter. The provided argument should be a pointer to a pointer of arbitrary type (e.g., void **).

Fortran NOTES

The :ref:`MPI_Alloc_mem` calls require the use of the iso_c_binding module for due to the use of TYPE(C_PTR).

use iso_c_binding

type(c_ptr) :: alloc_ptr
integer :: size, ierr
double precision, pointer :: array(:,:)

! A 2D array of 100 elements
size = 10 * 10
call MPI_Alloc_Mem(size * 8, MPI_INFO_NULL, alloc_ptr, ierr)

! Point to the array
call c_f_pointer(alloc_ptr, array, [10, 10])

! ... use the array ...

! Free the memory, no need for the alloc_ptr
call MPI_Free_mem(array, ierr)

ERRORS

.. seealso::
   * :ref:`MPI_Free_mem`