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module bindc_04_thread_data_module
use, intrinsic :: iso_c_binding
type, bind(C) :: thread_data
integer(c_int) :: n, m
type(c_ptr) :: a
end type thread_data
end module bindc_04_thread_data_module
module module_openmp_bindc_04
use iso_c_binding
implicit none
interface
subroutine GOMP_parallel (fn, data, num_threads, flags) bind (C, name="GOMP_parallel")
import :: c_funptr, c_ptr, c_int
type(c_funptr), value :: fn
type(c_ptr), value :: data
integer(c_int), value :: num_threads
integer(c_int), value :: flags
end subroutine
subroutine GOMP_barrier() bind(C, name="GOMP_barrier")
end subroutine
subroutine GOMP_critical_start() bind(C, name="GOMP_critical_start")
end subroutine
subroutine GOMP_critical_end() bind(C, name="GOMP_critical_end")
end subroutine
function omp_get_max_threads() bind(c, name="omp_get_max_threads")
import :: c_int
integer(c_int) :: omp_get_max_threads
end function omp_get_max_threads
function omp_get_thread_num() bind(c, name="omp_get_thread_num")
import :: c_int
integer(c_int) :: omp_get_thread_num
end function omp_get_thread_num
subroutine omp_set_num_threads(n) bind(c, name="omp_set_num_threads")
import :: c_int
integer(c_int), value :: n
end subroutine omp_set_num_threads
subroutine GOMP_atomic_start() bind(C, name="GOMP_atomic_start")
end subroutine
subroutine GOMP_atomic_end() bind(C, name="GOMP_atomic_end")
end subroutine
end interface
end module
subroutine lcompilers_initialise_array(data) bind(C)
use bindc_04_thread_data_module
use iso_c_binding
use module_openmp_bindc_04
implicit none
type(c_ptr), value :: data
type(thread_data), pointer :: tdata
real(c_float), pointer :: a(:,:)
integer(c_int) :: i, j, n, m, num_threads, chunk, leftovers, thread_num, start, end
call c_f_pointer(data, tdata)
n = tdata%n
m = tdata%m
call c_f_pointer(tdata%a, a, [n, m])
num_threads = omp_get_max_threads()
chunk = n / num_threads
leftovers = mod(n, num_threads)
thread_num = omp_get_thread_num()
start = chunk * thread_num
if (thread_num < leftovers) then
start = start + thread_num
else
start = start + leftovers
end if
end = start + chunk
if (thread_num < leftovers) then
end = end + 1
end if
do i = start + 1, end
do j = 1, m
a(i, j) = 12.91
end do
end do
call GOMP_barrier()
end subroutine
subroutine initialize_array(n, m, a)
use bindc_04_thread_data_module
use module_openmp_bindc_04
use iso_c_binding
implicit none
interface
subroutine lcompilers_initialise_array(data) bind(C)
use iso_c_binding
type(c_ptr), value :: data
end subroutine
end interface
integer(c_int), intent(in) :: n, m
real(c_float), dimension(:, :), intent(inout), pointer :: a
type(thread_data), target :: data
type(c_ptr) :: tdata
data%n = n
data%m = m
data%a = c_loc(a)
tdata = c_loc(data)
call GOMP_parallel(c_funloc(lcompilers_initialise_array), tdata, 0, 0)
end subroutine
program openmp_bindc_04
use omp_lib
use module_openmp_bindc_04
use bindc_04_thread_data_module
use iso_c_binding
implicit none
interface
subroutine initialize_array(n, m, a)
use iso_c_binding
integer(c_int), intent(in) :: n, m
real(c_float), intent(inout), dimension(:, :), pointer :: a
end subroutine
end interface
integer(c_int) :: n = 1902, m = 300
real(c_float), dimension(:, :), pointer :: a
allocate(a(n, m))
call omp_set_num_threads(4)
call initialize_array(n, m, a)
print *, "Done"
print *, a(1,2)
if (abs(a(1,2) - 12.91) > 1e-6) error stop
end program
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