ABSTRACT - Abstract Entity Definition

Synopsis

Syntax

• name str - The name of the abstract entity.
• library_name str (optional) - The name of the library from which the behaviour is taken. If the library_name is not specified, then the user must provide a .hase description of the behaviour. The HASE library currently contains the following:
  • sync - contains basic entities to deal with clocking and synchronisation issues.
• description str - The description of the abstract entity.
• service_nameX str - The name of a service to be defined by the inheriting entity.
• paramX str (optional) - Services may have some parameters. In that case, the service name is followed by a comma and a list of parameters separated by a comma. Each parameter must have a type followed by a name. Ex: SERVICE (tick, int no) defines the service tick with one integer parameter named no. The .hase description will be able to use the parameter 'no'. The abstract entity description must call the service tick with an integer parameter. Ex: tick(12);
• reference_parameter - This section of the abstract definition describes the parameters that are associated with the abstract entity. These parameters will be inherited by the inheriting concrete class (see entity). For example, a memory entity may have an array associated with it to hold the contents, and integer to hold the access time of the component. Careful selection of the parameters could result in reusable components. For example a cache entity might have parameters for its size, associativity and access time.

Example

ENTITYLIB (
ABSTRACT clocked (
DESCRIPTION ("two phases clock entities")
INTERFACE(
SERVICE (pre)
SERVICE (phase0)
SERVICE (phase1)
)
)



Ordinary (concrete) entities can inherit the services offered by clocked (i.e. pre, phase0 and phase1) by including in their definition the statement

EXTENDS (clocked)

In the corresponding entity.hase file these services can be invoked as shown in the following example. Note however that an entity that does this must not use a body label since this would also be inherited from the abstract entity.

$class_decls //entity references sim_entity_id bus; sim_entity_id add_res; sim_entity_id mul_res; //structures and variables t_rs_control Instruction, Register; int RS_no; int output_to_au; //methods void Output_to_au(); $class_defs void rsc::Output_to_au() { // Invoked by a Reservation Station: set output_to_au = 1 output_to_au = 1; } $pre bus = sim.get_entity_id("CDB"); add_res = sim.get_entity_id("ADD_RES"); output_to_au = 0; cur_state = RSC; strcpy(FUNC, "FREE"); dump_state(); $phase0 // predicate sim_from_port receive(input); sim_hold(5); // If there is an event from the CDB, copy function and tag number // into Register. if (sim_waiting(ev, receive) > 0) { SIM_CAST(t_rs_control, Instruction, ev); Register.instrn = Instruction.instrn; Register.tag_no = Instruction.tag_no; if (Register.instrn.function == VOID) strcpy(FUNC, "FREE"); else if (Register.instrn.function == ADD) strcpy(FUNC, "ADD"); else if (Register.instrn.function == SUB) strcpy(FUNC, "SUB"); else if (Register.instrn.function == MUL) strcpy(FUNC, "MUL"); else if (Register.instrn.function == DIV) strcpy(FUNC, "DIV"); dump_state(); } $phase1 // if output_to_au is set, send content of register to arithmetic unit if (output_to_au == 1) { send_CONTROL(output, Register); output_to_au = 0; }

rsc.hase

The code for clocked is as follows:

$class_decls int ClockPhase; int DONE; //clock reference sim_entity_id clk; $startup clk = sim.get_entity_id("CLOCK"); ((clock *)sim.get_entity(clk))->registering(get_id()); $body pre(); DONE = 1; // predicate sim_from_p start(clk); while (1) { sim_wait_for(start, ev); SIM_CAST(int, ClockPhase, ev); //to avoid memory leakage if (ClockPhase == 0) // First phase of clock phase0(); else // Second phase of clock phase1(); sim_schedule( clk, 0.0, CLOCK, SIM_PUT(int, DONE)); }

clocked.hase