External Interface

  This section describes the behavior when an HPF_CRAFT routine is called from HPF.

The calling convention and argument passing rules for HPF_CRAFT are a hybrid of those for HPF calling HPF_LOCAL and HPF calling HPF. Explicit interfaces are required. Where dummy arguments are private (default) storage, the HPF calling HPF_LOCAL conventions are used. Where dummy arguments are explicitly mapped, the calling convention matches HPF calling HPF.

There are a number of constraints on HPF_CRAFT routines that are called from HPF. The following is a list of restrictions placed on HPF_CRAFT routines called from HPF:

• Recursive HPF_CRAFT routines cannot be called from HPF.
• HPF_CRAFT routines called from HPF may only enter the routine at a single place (no alternate entries).
• An HPF_CRAFT supprogram may not be invoked directly or indirectly from within the body of a FORALL construct or within the body of an INDEPENDENT DO loop that is inside an HPF program.
• The attributes (type, kind, rank, optional, intent) of the dummy arguments in a supprogram called by HPF must match the attributes of the corresponding dummy arguments in the explicit interface.
• A dummy argument of an HPF_CRAFT supprogram called by HPF
  • must not be a procedure name.
  • must not have the POINTER attribute.
  • must not be sequential, unless it is also PE_PRIVATE.
  • must have assumed shape even when it is explicit shape in the interface.
  • if scalar, it must be mapped so that each processor has a copy of the argument.
• The default mapping of scalar dummy arguments and of scalar function results when an HPF program calls an HPF_CRAFT routine is that it is replicated on each processor.

If a dummy argument of an EXTRINSIC(`HPF_CRAFT') routine interface block is an array and the dummy argument of the HPF_CRAFT supprogram has the default private mapping, then the corresponding dummy argument in the specification of the HPF_CRAFT procedure must be an array of the same rank, type, and type parameters. When the extrinsic procedure is invoked, the dummy argument is associated with the local array that consists of the subgrid of the global array that is stored locally.

If the dummy argument of the HPF_CRAFT supprogram is explicitly mapped, it must have the same mapping as the dummy argument of the EXTRINSIC(`HPF_CRAFT') supprogram. Note that this restriction does not require actual and dummy arguments to match and is no more stringent than saying that mappings of dummy arguments in interface blocks must match those in the actual routine.