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program adios2_global_array_1d_read
use mpivars
use adios2
implicit none
! ADIOS2 variables
type(adios2_adios) :: adios
! MPI then ADIOS2 initialization
call init_mpi(234)
call adios2_init(adios, app_comm, ierr)
call reader()
! ADIOS2 then MPI finalization
call adios2_finalize(adios, ierr)
call finalize_mpi()
contains
subroutine reader
use mpivars
use decomp
use adios2
implicit none
character(len=256), parameter :: streamname = "adios2-global-array-1d-f.bp"
type(adios2_io) :: io
type(adios2_engine) :: engine
type(adios2_variable) :: var_g
integer :: step, istatus
! Application variables
! g = 1D distributed array, global shape and per-process size is fixed
real*4, dimension(:), allocatable :: g
integer :: ndims
integer*8, dimension(:), allocatable :: fixed_shape
integer*8, dimension(1) :: fixed_start, fixed_count
call adios2_declare_io (io, adios, 'input', ierr)
call adios2_open(engine, io, streamname, adios2_mode_read, ierr)
if (ierr .ne. 0) then
print '(" Failed to open stream: ",a)', streamname
print '(" open stream ierr=: ",i0)', ierr
return
endif
! Reading steps
step = 0
do
call adios2_begin_step(engine, adios2_step_mode_read, 0.0, istatus, ierr)
if (ierr /= 0) then
print '(" Failure when trying to get next step: ",a)', streamname
exit
endif
if (istatus == adios2_step_status_end_of_stream) then
! Stream has terminated, no more steps are available
!print '(" Input stream has terminated: ",a)', streamname
exit
endif
! Variable pointer MUST be retrieved every step, the reference
! will go invalid after adios2_end_step
call adios2_inquire_variable(var_g, io, "GlobalArray", ierr )
! Get variable dimensions and do decomposition in the first step
! These don't change for the stream in this example
if (step == 0) then
! fixed_shape is allocated in the next call
call adios2_variable_shape(fixed_shape, ndims, var_g, ierr)
call decompose_1d(fixed_shape(1), fixed_start(1), fixed_count(1))
allocate(g(fixed_count(1)))
write (*,100) "Read plan rank=", rank, &
" global shape = ", fixed_shape(1), &
" local count = ", fixed_count(1), &
" offset = ", fixed_start(1)
100 format (a,i2,a,i4,a,i1,a,i4)
endif
call adios2_set_selection(var_g, 1, fixed_start, fixed_count, ierr)
call adios2_get(engine, var_g, g, ierr)
call adios2_end_step(engine, ierr)
! g[] is now filled with data AFTER adios2_end_step/adios2_perform_gets
! or should call adios2_get(engine, var_g, g, adios2_mode_sync, ierr)
! to get it immediately in the get() call
step = step + 1
enddo
! Close the output
call adios2_close(engine, ierr)
deallocate(g)
deallocate(fixed_shape)
end subroutine reader
end program adios2_global_array_1d_read
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