Re: [myhdl-list] [RFC/PATCH] constant driver support

[Sébastien B. <seb...@mi...>]

Sorry about the word-wrap damage, here is the patch again.

diff -r e18493b5f0ad myhdl/_Waiter.py
--- a/myhdl/_Waiter.py	Fri May 20 21:07:24 2011 +0200
+++ b/myhdl/_Waiter.py	Sat Sep 10 15:51:22 2011 +0200
@@ -107,7 +107,7 @@
             elif isinstance(clause, join):
                 waiters.append(_Waiter(clause._generator(), clone))
             elif clause is None:
-                waiters.append(clone)
+                pass
             elif isinstance(clause, Exception):
                 waiters.append(clone)
                 if not exc:
@@ -194,7 +194,17 @@
             actives[id(wl)] = wl
             
 
-_kind = enum("SIGNAL_TUPLE", "EDGE_TUPLE", "SIGNAL", "EDGE", "DELAY", "UNDEFINED")
+class _InfiniteWaiter(_Waiter):
+    
+    __slots__ = ('generator')
+    
+    def __init__(self, generator):
+        self.generator = generator
+    
+    def next(self, waiters, actives, exc):
+        self.generator.next()
+
+_kind = enum("INFINITE", "SIGNAL_TUPLE", "EDGE_TUPLE", "SIGNAL", "EDGE", "DELAY", "UNDEFINED")
 
 
 def _inferWaiter(gen):
@@ -207,6 +217,8 @@
     # print ast.dump(root)
     v = _YieldVisitor(root)
     v.visit(root)
+    if v.kind == _kind.INFINITE:
+        return _InfiniteWaiter(gen)
     if v.kind == _kind.EDGE_TUPLE:
         return _EdgeTupleWaiter(gen)
     if v.kind == _kind.SIGNAL_TUPLE:
@@ -265,7 +277,9 @@
     def visit_Name(self, node):
         n = node.id
         node.kind = _kind.UNDEFINED
-        if n in self.root.symdict:
+        if n == "None":
+            node.kind = _kind.INFINITE
+        elif n in self.root.symdict:
             obj = self.root.symdict[n]
             if isinstance(obj, _Signal):
                 node.kind = _kind.SIGNAL
diff -r e18493b5f0ad myhdl/_always_comb.py
--- a/myhdl/_always_comb.py	Fri May 20 21:07:24 2011 +0200
+++ b/myhdl/_always_comb.py	Sat Sep 10 15:51:22 2011 +0200
@@ -29,7 +29,7 @@
 from myhdl._Signal import _Signal, _isListOfSigs
 from myhdl._util import _isGenFunc, _dedent
 from myhdl._cell_deref import _cell_deref
-from myhdl._Waiter import _Waiter, _SignalWaiter, _SignalTupleWaiter
+from myhdl._Waiter import _Waiter, _SignalWaiter, _SignalTupleWaiter, _InfiniteWaiter
 from myhdl._instance import _Instantiator
 
 class _error:
@@ -39,7 +39,6 @@
 _error.Scope = "always_comb argument should be a local function"
 _error.SignalAsInout = "signal (%s) used as inout in always_comb function argument"
 _error.EmbeddedFunction = "embedded functions in always_comb function argument not supported"
-_error.EmptySensitivityList= "sensitivity list is empty"
     
 def always_comb(func):
     if not isinstance( func, FunctionType):
@@ -200,8 +199,9 @@
         self.senslist = tuple(senslist)
         self.gen = self.genfunc()
         if len(self.senslist) == 0:
-            raise AlwaysCombError(_error.EmptySensitivityList)
-        if len(self.senslist) == 1:
+            W = _InfiniteWaiter
+            self.senslist = None
+        elif len(self.senslist) == 1:
             W = _SignalWaiter
         else:
             W = _SignalTupleWaiter
@@ -211,7 +211,7 @@
 
     def genfunc(self):
         senslist = self.senslist
-        if len(senslist) == 1:
+        if (senslist != None) and (len(senslist) == 1):
             senslist = senslist[0]
         func = self.func
         while 1:
diff -r e18493b5f0ad myhdl/conversion/_analyze.py
--- a/myhdl/conversion/_analyze.py	Fri May 20 21:07:24 2011 +0200
+++ b/myhdl/conversion/_analyze.py	Sat Sep 10 15:51:22 2011 +0200
@@ -1042,6 +1042,8 @@
             senslist = [n.obj]
         elif _isMem(n.obj):
             senslist = n.obj
+        elif n.obj is None:
+            pass
         else:
             self.raiseError(node, _error.UnsupportedYield)
         node.senslist = senslist
diff -r e18493b5f0ad myhdl/conversion/_toVHDL.py
--- a/myhdl/conversion/_toVHDL.py	Fri May 20 21:07:24 2011 +0200
+++ b/myhdl/conversion/_toVHDL.py	Sat Sep 10 15:51:22 2011 +0200
@@ -1354,17 +1354,18 @@
 
 
     def visit_Yield(self, node):
-        self.write("wait ")
+        self.write("wait")
         yieldObj = self.getObj(node.value)
-        if isinstance(yieldObj, delay):
-            self.write("for ")
-        elif isinstance(yieldObj, _WaiterList):
-            self.write("until ")
-        else:
-            self.write("on ")
-        self.context = _context.YIELD
-        self.visit(node.value)
-        self.context = _context.UNKNOWN
+        if not yieldObj is None:
+            if isinstance(yieldObj, delay):
+                self.write(" for ")
+            elif isinstance(yieldObj, _WaiterList):
+                self.write(" until ")
+            else:
+                self.write(" on ")
+            self.context = _context.YIELD
+            self.visit(node.value)
+            self.context = _context.UNKNOWN
         self.write(";")
 
 
diff -r e18493b5f0ad myhdl/conversion/_toVerilog.py
--- a/myhdl/conversion/_toVerilog.py	Fri May 20 21:07:24 2011 +0200
+++ b/myhdl/conversion/_toVerilog.py	Sat Sep 10 15:51:22 2011 +0200
@@ -1176,7 +1176,6 @@
 
     def visit_Yield(self, node):
         yieldObj = self.getObj(node.value)
-        assert node.senslist
         senslist = node.senslist
         if isinstance(yieldObj, delay):
             self.write("# ")
@@ -1184,9 +1183,11 @@
             self.visit(node.value)
             self.context = _context.UNKNOWN
             self.write(";")
-        else:
+        elif senslist:
             self.writeSensitivityList(senslist)
             self.write(";")
+        else:
+            self.write("wait(0);")