Parallel Programming in Fortran 95 using OpenMP - People

66 4. The OpenMP run-time library
4.3.2 OMP get wtick
This function returns the number of seconds between successive clock ticks. Its interface
declaration is:
function OMP_get_wtick()
real(8) :: OMP_get_wtick
end function OMP_get_wtick
4.4 The Fortran 90 module omp lib
The previously presented subroutines and functions have clearly defined interfaces which
need to be known by the calling program in order to call them correctly. This is achieved
through a Fortran 90 module called omp lib which has to be supplied by the OpenMPimplementation.
Even though, the following source code shows the content and aspect
such a module should at least have 1 :
module omp_lib
implicit none
!Defines standard variable precisions of the OpenMP-implementation
integer, parameter :: OMP_integer_kind = 4
integer, parameter :: OMP_logical_kind = 4
integer, parameter :: OMP_lock_kind = 8
integer, parameter :: OMP_nest_lock_kind = 8
!Defines the OpenMP version: OpenMP Fortran API v2.0
integer, parameter :: openmp_version = 200011
!Gives the explicit interface for each routine of the run-time library
interface
subroutine OMP_set_num_threads(number_of_threads)
integer(kind = OMP_integer_kind), intent(in) :: number_of_threads
end subroutine OMP_set_num_threads
function OMP_get_num_threads()
integer(kind = OMP_integer_kind) :: OMP_get_num_threads
end function OMP_get_num_threads
function OMP_get_max_threads()
integer(kind = OMP_integer_kind) :: OMP_get_max_threads
end function OMP_get_max_threads
function OMP_get_thread_num()
integer(kind = OMP_integer_kind) :: OMP_get_thread_num
end function OMP_get_thread_num
1 The presented source code will not work with many Fortran 90 compilers, because they do not
allow the use of parameter constants inside interface declarations. To solve this, it is necessary to
substitute manually the values of these constants into the declarations.