Added graph functions to compute analytical delay based on graph path.

compiler/base/graph_util.py

@@ -18,13 +18,16 @@ class timing_graph():
     def __init__(self):
         self.graph = defaultdict(set)
         self.all_paths = []
+        self.edge_mods = {}
 
-    def add_edge(self, src_node, dest_node):
-        """Adds edge to graph. Nodes added as well if they do not exist."""
+    def add_edge(self, src_node, dest_node, edge_mod):
+        """Adds edge to graph. Nodes added as well if they do not exist.
+           Module which defines the edge must be provided for timing information."""
         
         src_node = src_node.lower()
         dest_node = dest_node.lower()
         self.graph[src_node].add(dest_node)
+        self.edge_mods[(src_node, dest_node)] = edge_mod
 
     def add_node(self, node):
         """Add node to graph with no edges"""
@@ -34,8 +37,8 @@ class timing_graph():
             self.graph[node] = set()
             
     def remove_edges(self, node):
-        
         """Helper function to remove edges, useful for removing vdd/gnd"""
+        
         node = node.lower()
         self.graph[node] = set()    
             
@@ -95,6 +98,31 @@ class timing_graph():
         path.pop() 
         visited.remove(cur_node)    
 
+    def get_timing(self, path, corner, slew, load):
+        """Returns the analytical delays in the input path"""
+        
+        if len(path) == 0:
+            return []
+            
+        delays = []    
+        for i in range(len(path)-1):
+            
+            path_edge_mod = self.edge_mods[(path[i], path[i+1])]
+            
+            # On the output of the current stage, get COUT from all other mods connected
+            cout = 0
+            for node in self.graph[path[i+1]]:
+                output_edge_mode = self.edge_mods[(path[i+1], node)]
+                cout+=output_edge_mode.input_load()
+            # If at the last output, include the final output load    
+            if i == len(path)-2:
+               cout+=load
+            
+            delays.append(path_edge_mod.analytical_delay(corner, slew, cout))    
+            slew = delays[-1].slew
+            
+        return delays
+            
     def __str__(self):
         """ override print function output """
 

compiler/base/hierarchy_design.py

@@ -219,7 +219,7 @@ class hierarchy_design(hierarchy_spice.spice, hierarchy_layout.layout):
         for inp in input_pins+inout_pins:
             for out in output_pins+inout_pins:
                 if inp != out: #do not add self loops
-                    graph.add_edge(pin_dict[inp], pin_dict[out])        
+                    graph.add_edge(pin_dict[inp], pin_dict[out], self)        
  
     def __str__(self):
         """ override print function output """

compiler/base/hierarchy_spice.py

@@ -13,7 +13,7 @@ import tech
 from delay_data import *
 from wire_spice_model import *
 from power_data import *
-
+import logical_effort
 
 class spice():
     """
@@ -304,13 +304,27 @@ class spice():
 
     def analytical_delay(self, corner, slew, load=0.0):
         """Inform users undefined delay module while building new modules"""
-        debug.warning("Design Class {0} delay function needs to be defined"
+        relative_cap = logical_effort.convert_farad_to_relative_c(load)
+        stage_effort = self.get_stage_effort(relative_cap)
+        
+        # If it fails, then keep running with a valid object.
+        if stage_effort == None:
+            return delay_data(0.0, 0.0)
+            
+        abs_delay = stage_effort.get_absolute_delay()
+        corner_delay = self.apply_corners_analytically(abs_delay, corner)
+        SLEW_APPROXIMATION = 0.1
+        corner_slew = SLEW_APPROXIMATION*corner_delay
+        return delay_data(corner_delay, corner_slew)
+
+    def get_stage_effort(self, corner, slew, load=0.0):
+        """Inform users undefined delay module while building new modules"""
+        debug.warning("Design Class {0} logical effort function needs to be defined"
                       .format(self.__class__.__name__))
         debug.warning("Class {0} name {1}"
                       .format(self.__class__.__name__, 
                               self.name))         
-        # return 0 to keep code running while building
-        return delay_data(0.0, 0.0)
+        return None   
         
     def cal_delay_with_rc(self, corner, r, c ,slew, swing = 0.5):
         """ 

compiler/bitcells/bitcell.py

@@ -36,12 +36,22 @@ class bitcell(design.design):
         self.add_pin_types(self.type_list)
         self.nets_match = self.do_nets_exist(self.storage_nets)
         
-    def analytical_delay(self, corner, slew, load=0, swing = 0.5):
+    def get_stage_effort(self, load):
         parasitic_delay = 1
         size = 0.5 #This accounts for bitline being drained thought the access TX and internal node
         cin = 3 #Assumes always a minimum sizes inverter. Could be specified in the tech.py file.
         return logical_effort.logical_effort('bitline', size, cin, load, parasitic_delay, False)
  
+    def input_load(self):
+        """Return the relative capacitance of the access transistor gates"""
+        #This is a handmade cell so the value must be entered in the tech.py file or estimated.
+        #Calculated in the tech file by summing the widths of all the related gates and dividing by the minimum width.
+        
+        #FIXME: The graph algorithm will apply this capacitance to the bitline load as they cannot be
+        # distinguished currently
+        access_tx_cin = parameter["6T_access_size"]/drc["minwidth_tx"]
+        return 2*access_tx_cin
+ 
     def get_all_wl_names(self):
         """ Creates a list of all wordline pin names """
         row_pins = ["wl"]    

compiler/bitcells/bitcell_1rw_1r.py

@@ -141,8 +141,8 @@ class bitcell_1rw_1r(design.design):
         pin_dict = {pin:port for pin,port in zip(self.pins, port_nets)} 
         #Edges hardcoded here. Essentially wl->bl/br for both ports.
         # Port 0 edges
-        graph.add_edge(pin_dict["wl0"], pin_dict["bl0"])   
-        graph.add_edge(pin_dict["wl0"], pin_dict["br0"])   
+        graph.add_edge(pin_dict["wl0"], pin_dict["bl0"], self)   
+        graph.add_edge(pin_dict["wl0"], pin_dict["br0"], self)   
         # Port 1 edges
-        graph.add_edge(pin_dict["wl1"], pin_dict["bl1"])   
-        graph.add_edge(pin_dict["wl1"], pin_dict["br1"])   
+        graph.add_edge(pin_dict["wl1"], pin_dict["bl1"], self)   
+        graph.add_edge(pin_dict["wl1"], pin_dict["br1"], self)   

compiler/bitcells/bitcell_1w_1r.py

@@ -139,6 +139,6 @@ class bitcell_1w_1r(design.design):
         pin_dict = {pin:port for pin,port in zip(self.pins, port_nets)} 
         #Edges hardcoded here. Essentially wl->bl/br for both ports.
         # Port 0 edges
-        graph.add_edge(pin_dict["wl1"], pin_dict["bl1"])   
-        graph.add_edge(pin_dict["wl1"], pin_dict["br1"])     
+        graph.add_edge(pin_dict["wl1"], pin_dict["bl1"], self)   
+        graph.add_edge(pin_dict["wl1"], pin_dict["br1"], self)     
         # Port 1 is a write port, so its timing is not considered here.      

compiler/bitcells/pbitcell.py

@@ -973,6 +973,6 @@ class pbitcell(design.design):
 
         for pin_zip in [rw_pin_names, r_pin_names]: 
             for wl,bl,br in pin_zip:
-                graph.add_edge(pin_dict[wl],pin_dict[bl])
-                graph.add_edge(pin_dict[wl],pin_dict[br])
+                graph.add_edge(pin_dict[wl],pin_dict[bl], self)
+                graph.add_edge(pin_dict[wl],pin_dict[br], self)
 

compiler/bitcells/replica_bitcell_1rw_1r.py

@@ -46,8 +46,8 @@ class replica_bitcell_1rw_1r(design.design):
         pin_dict = {pin:port for pin,port in zip(self.pins, port_nets)} 
         #Edges hardcoded here. Essentially wl->bl/br for both ports.
         # Port 0 edges
-        graph.add_edge(pin_dict["wl0"], pin_dict["bl0"])   
-        graph.add_edge(pin_dict["wl0"], pin_dict["br0"])   
+        graph.add_edge(pin_dict["wl0"], pin_dict["bl0"], self)   
+        graph.add_edge(pin_dict["wl0"], pin_dict["br0"], self)   
         # Port 1 edges
         graph.add_edge(pin_dict["wl1"], pin_dict["bl1"])   
         graph.add_edge(pin_dict["wl1"], pin_dict["br1"])  

compiler/bitcells/replica_bitcell_1w_1r.py

@@ -47,6 +47,6 @@ class replica_bitcell_1w_1r(design.design):
         pin_dict = {pin:port for pin,port in zip(self.pins, port_nets)} 
         #Edges hardcoded here. Essentially wl->bl/br for the read port.
         # Port 1 edges
-        graph.add_edge(pin_dict["wl1"], pin_dict["bl1"])   
-        graph.add_edge(pin_dict["wl1"], pin_dict["br1"])   
+        graph.add_edge(pin_dict["wl1"], pin_dict["bl1"], self)   
+        graph.add_edge(pin_dict["wl1"], pin_dict["br1"], self)   
         # Port 0 is a write port, so its timing is not considered here.

compiler/characterizer/delay.py

@@ -1275,36 +1275,65 @@ class delay(simulation):
             # Add test cycle of read/write port pair. One port could have been used already, but the other has not.
             self.gen_test_cycles_one_port(cur_read_port, cur_write_port)
 
+    def sum_delays(self, delays):
+        """Adds the delays (delay_data objects) so the correct slew is maintained"""
+        delay = delays[0]
+        for i in range(1, len(delays)):
+            delay+=delays[i]
+        return delay 
+        
     def analytical_delay(self, slews, loads):
         """ 
         Return the analytical model results for the SRAM. 
         """
         if OPTS.num_rw_ports > 1 or OPTS.num_w_ports > 0 and OPTS.num_r_ports > 0:
             debug.warning("Analytical characterization results are not supported for multiport.")
+        
+        # Probe set to 0th bit, does not matter for analytical delay.
+        self.set_probe('0', 0)
+        self.create_graph()
+        self.set_internal_spice_names()
         self.create_measurement_names()
-        power = self.analytical_power(slews, loads)
-        port_data = self.get_empty_measure_data_dict()
-        relative_loads = [logical_effort.convert_farad_to_relative_c(c_farad) for c_farad in loads]
+        
+        port = self.read_ports[0]
+        self.graph.get_all_paths('{}{}'.format(tech.spice["clk"], port), 
+                                 '{}{}_{}'.format(self.dout_name, port, self.probe_data))
+        
+        # Select the path with the bitline (bl)
+        bl_name,br_name = self.get_bl_name(self.graph.all_paths, port)
+        bl_path = [path for path in self.graph.all_paths if bl_name in path][0]
+        
+        debug.info(1,'Slew, Load, Delay(ns), Slew(ns)')
         for slew in slews:
-            for load in relative_loads:
-                self.set_load_slew(load,slew)
-                bank_delay = self.sram.analytical_delay(self.corner, self.slew,self.load)
-                for port in self.all_ports:
-                    for mname in self.delay_meas_names+self.power_meas_names:
-                        if "power" in mname:
-                            port_data[port][mname].append(power.dynamic)
-                        elif "delay" in mname:
-                            port_data[port][mname].append(bank_delay[port].delay/1e3)
-                        elif "slew" in mname:
-                            port_data[port][mname].append(bank_delay[port].slew/1e3)
-                        else:
-                            debug.error("Measurement name not recognized: {}".format(mname),1)
-        period_margin = 0.1
-        risefall_delay = bank_delay[self.read_ports[0]].delay/1e3
-        sram_data = { "min_period":risefall_delay*2*period_margin, 
-                      "leakage_power": power.leakage}
-        debug.info(2,"SRAM Data:\n{}".format(sram_data))                 
-        debug.info(2,"Port Data:\n{}".format(port_data)) 
+            for load in loads:
+                path_delays = self.graph.get_timing(bl_path, self.corner, slew, load)
+                total_delay = self.sum_delays(path_delays)
+                debug.info(1,'{}, {}, {}, {}'.format(slew,load,total_delay.delay/1e3, total_delay.slew/1e3))
+                
+        debug.error('Not finished with graph delay characterization.', 1)
+        # power = self.analytical_power(slews, loads)
+        # port_data = self.get_empty_measure_data_dict()
+        # relative_loads = [logical_effort.convert_farad_to_relative_c(c_farad) for c_farad in loads]
+        # for slew in slews:
+            # for load in relative_loads:
+                # self.set_load_slew(load,slew)
+                # bank_delay = self.sram.analytical_delay(self.corner, self.slew,self.load)
+                # for port in self.all_ports:
+                    # for mname in self.delay_meas_names+self.power_meas_names:
+                        # if "power" in mname:
+                            # port_data[port][mname].append(power.dynamic)
+                        # elif "delay" in mname:
+                            # port_data[port][mname].append(bank_delay[port].delay/1e3)
+                        # elif "slew" in mname:
+                            # port_data[port][mname].append(bank_delay[port].slew/1e3)
+                        # else:
+                            # debug.error("Measurement name not recognized: {}".format(mname),1)
+        # period_margin = 0.1
+        # risefall_delay = bank_delay[self.read_ports[0]].delay/1e3
+        # sram_data = { "min_period":risefall_delay*2*period_margin, 
+                      # "leakage_power": power.leakage}
+        # debug.info(2,"SRAM Data:\n{}".format(sram_data))                 
+        # debug.info(2,"Port Data:\n{}".format(port_data)) 
         return (sram_data,port_data)
         
     

compiler/example_configs/example_config_scn4m_subm.py

@@ -15,3 +15,5 @@ output_name = "sram_{0}_{1}_{2}".format(word_size,num_words,tech_name)
 drc_name = "magic"
 lvs_name = "netgen"
 pex_name = "magic"
+
+netlist_only = True

compiler/modules/sense_amp.py

@@ -41,7 +41,7 @@ class sense_amp(design.design):
         bitline_pmos_size = 8 #FIXME: This should be set somewhere and referenced. Probably in tech file.
         return spice["min_tx_drain_c"]*(bitline_pmos_size/parameter["min_tx_size"])#ff   
         
-    def analytical_delay(self, corner, slew, load):
+    def get_stage_effort(self, load):
         #Delay of the sense amp will depend on the size of the amp and the output load.
         parasitic_delay = 1
         cin = (parameter["sa_inv_pmos_size"] + parameter["sa_inv_nmos_size"])/drc("minwidth_tx")

compiler/pgates/pinv.py

@@ -277,6 +277,11 @@ class pinv(pgate.pgate):
            units relative to the minimum width of a transistor"""
         return self.nmos_size + self.pmos_size
       
+    def input_load(self):
+        """Return the capacitance of the gate connection in generic capacitive
+           units relative to the minimum width of a transistor"""
+        return self.nmos_size + self.pmos_size
+      
     def get_stage_effort(self, cout, inp_is_rise=True):
         """Returns an object representing the parameters for delay in tau units.
            Optional is_rise refers to the input direction rise/fall. Input inverted by this stage.

compiler/pgates/pnand2.py

@@ -254,6 +254,10 @@ class pnand2(pgate.pgate):
         """Return the relative input capacitance of a single input"""
         return self.nmos_size+self.pmos_size
     
+    def input_load(self):
+        """Return the relative input capacitance of a single input"""
+        return self.nmos_size+self.pmos_size
+    
     def get_stage_effort(self, cout, inp_is_rise=True):
         """Returns an object representing the parameters for delay in tau units.
            Optional is_rise refers to the input direction rise/fall. Input inverted by this stage.

compiler/pgates/single_level_column_mux.py

@@ -189,7 +189,7 @@ class single_level_column_mux(pgate.pgate):
                       width=self.bitcell.width,
                       height=self.height)
         
-    def analytical_delay(self, corner, slew, load):
+    def get_stage_effort(self, corner, slew, load):
         """Returns relative delay that the column mux. Difficult to convert to LE model."""
         parasitic_delay = 1
         cin = 2*self.tx_size #This is not CMOS, so using this may be incorrect.