Add new DFF. Create DFF module. Start dff_array, not tested.

compiler/modules/dff.py

@@ -0,0 +1,29 @@
+import globals
+import design
+from math import log
+import design
+from tech import GDS,layer
+import utils
+
+class dff(design.design):
+    """
+    Memory address flip-flop
+    """
+
+    pin_names = ["d", "clk", "q", "vdd", "gnd"]
+    (width,height) = utils.get_libcell_size("dff", GDS["unit"], layer["boundary"])
+    pin_map = utils.get_libcell_pins(pin_names, "dff", GDS["unit"], layer["boundary"])
+    
+    def __init__(self, name="dff"):
+        design.design.__init__(self, name)
+
+        self.width = dff.width
+        self.height = dff.height
+        self.pin_map = dff.pin_map
+    
+    def analytical_delay(self, slew, load = 0.0):
+        # dont know how to calculate this now, use constant in tech file
+        from tech import spice
+        result = self.return_delay(spice["dff_delay"], spice["dff_slew"])
+        return result
+