Processor Description Languages

4.4 Instruction-set Grammar 77

opn mult_acc_prim()

{

action {

stage EX1..EX2:

G `EX2` = MR `EX2`; // one stage later than mult. operands

H `EX2` = macc(D `EX1`, E `EX1`, G `EX2`) rsrc(F `EX1`);

}

}

This example also shows that it is possible to annotate an extra (abstract) resource

to a statement in the action attribute, for example, to model a hardware conflict

on internal resources of a primitive operation. If the

macc operation would use

resource

F in both stage EX1 and stage EX2,this can be annotated as rsrc(F ‘EX1,EX2‘).

From this, the tools can then derive that a new

macc operation can only be started

every two cycles

Section 4.5.2 explains how to solve ...