pytholite/io: support token pull

migen/pytholite/compiler.py

@@ -154,7 +154,7 @@ class _Compiler:
 					raise NotImplementedError
 			from_model.append((tregs, fstatement.value))
 		
-		states, exit_states = gen_io(self, model, args, from_model)
+		states, exit_states = gen_io(self, modelname, model, args, from_model)
 		sa.assemble(states, exit_states)
 		return fstatement
 	
@@ -222,7 +222,7 @@ class _Compiler:
 			if not isinstance(yvalue, ast.Call) or not isinstance(yvalue.func, ast.Name):
 				raise NotImplementedError("Unrecognized I/O pattern")
 			callee = self.symdict[yvalue.func.id]
-			states, exit_states = gen_io(self, callee, yvalue.args, [])
+			states, exit_states = gen_io(self, None, callee, yvalue.args, [])
 			sa.assemble(states, exit_states)
 		else:
 			raise NotImplementedError

migen/pytholite/expr.py

@@ -19,6 +19,10 @@ class ExprCompiler:
 			return self.visit_expr_name(node)
 		elif isinstance(node, ast.Num):
 			return self.visit_expr_num(node)
+		elif isinstance(node, ast.Attribute):
+			return self.visit_expr_attribute(node)
+		elif isinstance(node, ast.Subscript):
+			return self.visit_expr_subscript(node)
 		else:
 			raise NotImplementedError
 	
@@ -102,3 +106,10 @@ class ExprCompiler:
 	
 	def visit_expr_num(self, node):
 		return Constant(node.n)
+	
+	def visit_expr_attribute(self, node):
+		raise NotImplementedError
+	
+	def visit_expr_subscript(self, node):
+		raise NotImplementedError
+	

migen/pytholite/io.py

@@ -4,6 +4,7 @@ from migen.fhdl.structure import *
 from migen.flow.actor import *
 from migen.actorlib.sim import *
 from migen.pytholite.fsm import *
+from migen.pytholite.expr import ExprCompiler
 
 class Pytholite:
 	def get_fragment(self):
@@ -18,7 +19,28 @@ def make_io_object(dataflow=None):
 	else:
 		return DFPytholite(*dataflow)
 
-def gen_df_io(compiler, to_model, from_model):
+class _TokenPullExprCompiler(ExprCompiler):
+	def __init__(self, symdict, modelname, ep):
+		super().__init__(symdict)
+		self.modelname = modelname
+		self.ep = ep
+	
+	def visit_expr_subscript(self, node):
+		# check that we are subscripting <modelname>.value
+		if not isinstance(node.value, ast.Attribute) \
+		  or node.value.attr != "value" \
+		  or not isinstance(node.value.value, ast.Name) \
+		  or node.value.value.id != self.modelname:
+			raise NotImplementedError
+		
+		if not isinstance(node.slice, ast.Index):
+			raise NotImplementedError
+		field = ast.literal_eval(node.slice.value)
+		signal = getattr(self.ep.token, field)
+		
+		return signal
+
+def gen_df_io(compiler, modelname, to_model, from_model):
 	if len(to_model) == 1 or len(to_model) == 2:
 		epname = ast.literal_eval(to_model[0])
 		ep = compiler.ioo.endpoints[epname]
@@ -27,9 +49,22 @@ def gen_df_io(compiler, to_model, from_model):
 	
 	if len(to_model) == 1:
 		# token pull from sink
-		raise NotImplementedError # TODO
+		if not isinstance(ep, Sink):
+			raise TypeError("Attempted to pull from source")
+		ec = _TokenPullExprCompiler(compiler.symdict, modelname, ep)
+		state = []
+		for target_regs, expr in from_model:
+			cexpr = ec.visit_expr(expr)
+			state += [reg.load(cexpr) for reg in target_regs]
+		state += [
+			ep.ack.eq(1),
+			If(~ep.stb, AbstractNextState(state))
+		]
+		return [state], [state]
 	else:
 		# token push to source
+		if not isinstance(ep, Source):
+			raise TypeError("Attempted to push to sink")
 		if from_model:
 			raise TypeError("Attempted to read from pushed token")
 		d = to_model[1]
@@ -46,8 +81,8 @@ def gen_df_io(compiler, to_model, from_model):
 		]
 		return [state], [state]
 
-def gen_io(compiler, model, to_model, from_model):
+def gen_io(compiler, modelname, model, to_model, from_model):
 	if model == Token:
-		return gen_df_io(compiler, to_model, from_model)
+		return gen_df_io(compiler, modelname, to_model, from_model)
 	else:
 		raise NotImplementedError