actions.h File Reference

Go to the source code of this file.

Classes
class	bm::ActionPrimitive< Args >

Macros
#define	REGISTER_PRIMITIVE(primitive_name)
#define	REGISTER_PRIMITIVE_W_NAME(primitive_name, primitive)

Detailed Description

Each action primitive supported by the target needs to be declared as a functor. This is how you declare one:

class SetField :  public ActionPrimitive<Field &, const Data &> {
  void operator ()(Field &f, const Data &d) {
    f.set(d);
  }
};
 
class Add :  public ActionPrimitive<Field &, const Data &, const Data &> {
  void operator ()(Field &f, const Data &d1, const Data &d2) {
    f.add(d1, d2);
  }
};

You can then register them like this:

REGISTER_PRIMITIVE(SetField)
REGISTER_PRIMITIVE(Add)

And use them by their name in the P4 program / JSON file:

e.g. SetField(hdrA.f1, 99);

Valid functor parameters for an action primitive include:

• const Data & for any P4 numerical values (it can be a P4 constant, a field, action data or the result of an expression).
• Data & for a writable P4 numerical value (essentially a field)
• [const] Field & for P4 field references
• [const] Header & for P4 header references
• const NamedCalculation & for P4 field list calculations
• [const] MeterArray &
• [const] CounterArray &
• [const] RegisterArray &
• [const] HeaderUnion &
• [const] StackIface & for arbitrary P4 stacks
• [const] HeaderStack & for P4 header stacks
• [const] HeaderUnionStack & for P4 header union stacks
• const std::string & or const char * for strings
• const std::vector<Data> for lists of numerical values

You can declare and register primitives anywhere in your switch target C++ code.

Macro Definition Documentation

REGISTER_PRIMITIVE

#define REGISTER_PRIMITIVE

(

primitive_name

)

Value:

  bool primitive_name##_create_ =                                           \
      bm::ActionOpcodesMap::get_instance()->register_primitive(             \
          #primitive_name,                                                  \
          [](){ return std::unique_ptr<::bm::ActionPrimitive_>(             \
              new primitive_name()); })

When implementing an action primitive for a target, this macro needs to be called to make this module aware of the primitive existence.

REGISTER_PRIMITIVE_W_NAME

#define REGISTER_PRIMITIVE_W_NAME	(		primitive_name,
			primitive
	)

Value:

  bool primitive##_create_ =                                            \
      bm::ActionOpcodesMap::get_instance()->register_primitive(         \
          primitive_name,                                               \
          [](){ return std::unique_ptr<::bm::ActionPrimitive_>(         \
              new primitive()); })

This macro can also be called when registering a primitive for a target, in case you want to register the primitive under a different name than its functor name