fsm.add() supports keep attributes for specifying the signal sustain length.

Author: shtaxxx

sample/tests/lib_fsm/delayed_cond/led.py

@@ -20,7 +20,7 @@ def mkLed():
 
     # assert valid if the condition is satisfied
     # then de-assert 3 cycles later with same condition
-    fsm.add( valid(1), cond=c)
+    fsm.add( valid(1), cond=c, keep=3)
     fsm.add( valid(0), cond=c, delay=3)
     fsm.goto_next(cond=c)
 
@@ -33,7 +33,7 @@ def mkLed():
     # assert valid 1 cycle later if the condition is satisfied now
     # then de-assert 4 cycles later with same condition
     for i in range(8):
-        fsm.add( valid(1), cond=c, delay=1)
+        fsm.add( valid(1), cond=c, delay=1, keep=3)
         fsm.add( valid(0), cond=c, delay=4 )
         fsm.goto_next(cond=c)
 

veriloggen/lib/fsm.py

@@ -92,7 +92,16 @@ def add_delayed_cond(self, statement, index, delay):
 
     #---------------------------------------------------------------------------
     def add(self, *statement, **kwargs):
+        keep = kwargs['keep'] if 'keep' in kwargs else None
         delay = kwargs['delay'] if 'delay' in kwargs else None
+        
+        if keep is not None:
+            del kwargs['keep']
+            for i in range(keep):
+                kwargs['delay'] = i if delay is None else delay + i
+                self.add(*statement, **kwargs)
+            return self
+        
         if delay is not None and delay > 0:
             self.add_delayed_state(delay)
             index = self.current()
@@ -106,6 +115,7 @@ def add(self, *statement, **kwargs):
             return self
 
         cond = kwargs['cond'] if 'cond' in kwargs else None
+        
         if cond is not None:
             statement = [ vtypes.If(cond)(*statement) ]