From c1b8492b614978348b45db8dcd3194e320770711 Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sebastien@milkymist.org>
Date: Fri, 9 Nov 2012 20:12:15 +0100
Subject: [PATCH] pytholite/compiler: go to next state

---
 migen/pytholite/compiler.py | 53 ++++++++++++++++++++++++++-----------
 1 file changed, 37 insertions(+), 16 deletions(-)

diff --git a/migen/pytholite/compiler.py b/migen/pytholite/compiler.py
index a46176a7c..eebe24794 100644
--- a/migen/pytholite/compiler.py
+++ b/migen/pytholite/compiler.py
@@ -68,30 +68,51 @@ class _Compiler:
 		if isinstance(node, ast.Module) \
 		  and len(node.body) == 1 \
 		  and isinstance(node.body[0], ast.FunctionDef):
-			return self.visit_block(node.body[0].body)
+			states, exit_states = self.visit_block(node.body[0].body)
+			return states
 		else:
 			raise NotImplementedError
 	
 	# blocks and statements
 	def visit_block(self, statements):
 		states = []
+		exit_states = []
 		for statement in statements:
-			if isinstance(statement, ast.Assign):
-				op = self.visit_assign(statement)
-				if op:
-					states.append(op)
-			elif isinstance(statement, ast.If):
-				test = self.visit_expr(statement.test)
-				states_t = self.visit_block(statement.body)
-				states_f = self.visit_block(statement.orelse)
-				test_state_stmt = If(test, _AbstractNextState(states_t[0]))
-				if states_f:
-					test_state_stmt.Else(_AbstractNextState(states_f[0]))
-				states.append([test_state_stmt])
-				states += states_t + states_f
+			n_states, n_exit_states = self.visit_statement(statement)
+			if n_states:
+				states += n_states
+				for exit_state in exit_states:
+					exit_state.insert(0, _AbstractNextState(n_states[0]))
+				exit_states = n_exit_states
+		return states, exit_states
+	
+	# entry state is first state returned
+	def visit_statement(self, statement):
+		states = []
+		exit_states = []
+		if isinstance(statement, ast.Assign):
+			op = self.visit_assign(statement)
+			if op:
+				states.append(op)
+				exit_states.append(op)
+		elif isinstance(statement, ast.If):
+			test = self.visit_expr(statement.test)
+			states_t, exit_states_t = self.visit_block(statement.body)
+			states_f, exit_states_f  = self.visit_block(statement.orelse)
+			
+			test_state_stmt = If(test, _AbstractNextState(states_t[0]))
+			test_state = [test_state_stmt]
+			if states_f:
+				test_state_stmt.Else(_AbstractNextState(states_f[0]))
 			else:
-				raise NotImplementedError
-		return states
+				exit_states.append(test_state)
+			
+			states.append(test_state)
+			states += states_t + states_f
+			exit_states += exit_states_t + exit_states_f
+		else:
+			raise NotImplementedError
+		return states, exit_states
 	
 	def visit_assign(self, node):
 		if isinstance(node.targets[0], ast.Name):