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6.2.2. Window Attributes

The following three attributes are cached with a window, when the window is created.
[ MPI_WIN_BASE]window base address.
[ MPI_WIN_SIZE] window size, in bytes.
[ MPI_WIN_DISP_UNIT]displacement unit associated with the window.

In C, calls to MPI_Win_get_attr(win, MPI_WIN_BASE, &base, &flag),
MPI_Win_get_attr(win, MPI_WIN_SIZE, &size, &flag) and
MPI_Win_get_attr(win, MPI_WIN_DISP_UNIT, &disp_unit, &flag) will return in base a pointer to the start of the window win, and will return in size and disp_unit pointers to the size and displacement unit of the window, respectively. And similarly, in C++.

In Fortran, calls to MPI_WIN_GET_ATTR(win, MPI_WIN_BASE, base, flag, ierror),
MPI_WIN_GET_ATTR(win, MPI_WIN_SIZE, size, flag, ierror) and
MPI_WIN_GET_ATTR(win, MPI_WIN_DISP_UNIT, disp_unit, flag, ierror) will return in base, size and disp_unit the (integer representation of) the base address, the size and the displacement unit of the window win, respectively. (The window attribute access functions are defined in Section New Attribute Caching Functions .)

The other ``window attribute,'' namely the group of processes attached to the window, can be retrieved using the call below.

MPI_WIN_GET_GROUP(win, group)
[ IN win] window object (handle)
[ OUT group] group of processes which share access to the window (handle)

int MPI_Win_get_group(MPI_Win win, MPI_Group *group)
MPI_WIN_GET_GROUP(WIN, GROUP, IERROR)
INTEGER WIN, GROUP, IERROR
MPI::Group MPI::Win::Get_group() const

MPI_WIN_GET_GROUP returns a duplicate of the group of the communicator used to create the window. associated with win. The group is returned in group.