FortCL

Fortran wrapper library providing OpenCL functionality. It uses (and includes) the "clFortran" interface code available from https://github.com/cass-support/clfortran.

Compiling

The Makefile picks-up the compiler, flags etc. from environment variables. You will need to set F90 (and optionally, F90FLAGS). At link time you will need to link with the OpenCL run-time libraries on your system.

Controlling runtime behaviour"

There are 3 environment variables to control the OpenCL execution at runtime:

• FORTCL_KERNELS_FILE: Allows to specify at run-time the binary or source code filename containing the OpenCL kernels to execute.

• FORTCL_PLATFORM: Integer that selects in which OpenCL platform the kernels are going to be executed. The list of OpenCL platforms is a 1-based indexing list that can be queried with the clinfo command. If this variable is not set, the kernels will be launched on platform 1 (first available).

• FORTCL_VERBOSE: Boolean value to request more verbose information of the OpenCL runtime execution. It is considered true if this environment variable exists and is set to a value other than 0.

Example

There are three examples in the examples directory but in short:

program fcl_test
  implicit none
  use iso_c_binding, only: c_intptr_t
  use fortcl
  character(len=*) :: filename = "/my/compiled/kernels.aocx"
  integer(c_intptr_t), target :: device_buffer
  ! Initialise the OpenCL device and environment
  call ocl_env_init()
  ! Load a kernel (it can be a source file or a pre-compiled object)
  call add_kernels(1, "my_ocl_kernel", filename)
  ! Create a read-write buffer on the device
  device_buffer = create_rw_buffer(num_bytes)
  ! ...
  ! OpenCL-specific code here to set kernel arguments and
  ! launch kernel.
  ! ...
  ! Clean up
  call ocl_release()
end program fcl_test