Operator Reference

query_available_compute_devicesT_query_available_compute_devicesQueryAvailableComputeDevicesQueryAvailableComputeDevicesquery_available_compute_devices (Operator)

query_available_compute_devicesT_query_available_compute_devicesQueryAvailableComputeDevicesQueryAvailableComputeDevicesquery_available_compute_devices — Get the list of available compute devices.

Signature

query_available_compute_devices( : : : DeviceIdentifier)

Description

Returns the list of available compute devices. Use get_compute_device_infoget_compute_device_infoGetComputeDeviceInfoGetComputeDeviceInfoget_compute_device_info to query information on a specific device. Use open_compute_deviceopen_compute_deviceOpenComputeDeviceOpenComputeDeviceopen_compute_device to open a device in HALCON.

At present, HALCON only supports OpenCL compatible GPUs supporting the OpenCL extension cl_khr_byte_addressable_store and image objects. If you are not sure whether a certain device is supported, please refer to the manufacturer.

Be aware that currently it is not possible to use OpenCL via the Windows Remote Desktop, because Windows Remote Desktop does not allow access to the graphics driver. You may use a VNC solution to use OpenCL on a remote computer. Of course you can use OpenCL via ssh on a Linux machine.

It is recommended to install the latest graphics drivers available for your GPU. To access the GPU on a Linux system you should be member of the 'video' group.

Execution Information

Multithreading type: mutually exclusive (runs in parallel with other non-exclusive operators, but not with itself).
Multithreading scope: global (may be called from any thread).
Processed without parallelization.

Parameters

DeviceIdentifierDeviceIdentifierDeviceIdentifierdeviceIdentifierdevice_identifier (output_control) integer-array → (integer)

List of available compute devices.

Example (HDevelop)

query_available_compute_devices (DeviceIdentifiers)
for Index := 0 to |DeviceIdentifiers|-1 by 1
  get_compute_device_info (DeviceIdentifiers[Index], 'name', DeviceName)
  get_compute_device_info (DeviceIdentifiers[Index], 'vendor', DeviceVendor)
  if (DeviceVendor == 'NVIDIA Corporation' and \
    DeviceName == 'GeForce 8800 Ultra')
    open_compute_device (DeviceIdentifiers[Index], DeviceHandle)
    break
  endif
endfor
*
init_compute_device (DeviceHandle, 'derivate_gauss')
read_image (Image, 'rings_and_nuts')
*
* Gaussian convolution on a compute device
activate_compute_device (DeviceHandle)
derivate_gauss (Image, DerivGauss, 5, 'none')
*
* Gaussian convolution on the CPU
deactivate_compute_device (DeviceHandle)
derivate_gauss (Image, DerivGauss, 5, 'none')

Result

query_available_compute_devicesquery_available_compute_devicesQueryAvailableComputeDevicesQueryAvailableComputeDevicesquery_available_compute_devices returns the value 2 ( H_MSG_TRUE) .

Possible Successors

get_compute_device_infoget_compute_device_infoGetComputeDeviceInfoGetComputeDeviceInfoget_compute_device_info, open_compute_deviceopen_compute_deviceOpenComputeDeviceOpenComputeDeviceopen_compute_device

Module

Foundation

Operators