def lower_next(done_stage: vast.IntConst, ns: NextState):
"""
done_stage is the index of the final stage which just
holds the all the values in the register.
"""
# The computation is finished; transition to the done stage.
if isinstance(ns, Done):
return vast.Rvalue(done_stage)
elif isinstance(ns, DirectNext):
return vast.Rvalue(vast.IntConst(ns.state))
elif isinstance(ns, CondNext):
return vast.Cond(
vast.Rvalue(vast.Identifier(ns.cond.name)),
vast.IntConst(ns.on_true),
vast.IntConst(ns.on_false),
)
else:
raise ValueError("Malformed AST, expected next: %s" % ns.pretty())
def visit_Cond(self, node):
cond = self.visit(node.condition)
true_value = self.visit(node.true_value)
false_value = self.visit(node.false_value)
return vast.Cond(cond, true_value, false_value)