From 3cfe74cefbd4a5f5fcc3efed54a92e3d10f1fe02 Mon Sep 17 00:00:00 2001
From: Matt Guthaus <mrg+openram@ucsc.edu>
Date: Wed, 28 Nov 2018 16:55:04 -0800
Subject: [PATCH] Functional simulation uses threshold for high and low noise
 margins

---
 compiler/characterizer/functional.py | 9 +++++----
 compiler/characterizer/simulation.py | 3 +++
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/compiler/characterizer/functional.py b/compiler/characterizer/functional.py
index b99e644c..5255621b 100644
--- a/compiler/characterizer/functional.py
+++ b/compiler/characterizer/functional.py
@@ -29,6 +29,7 @@ class functional(simulation):
         self.set_spice_constants()
         self.set_stimulus_variables()
         self.create_signal_names()
+
         
         # Number of checks can be changed
         self.num_cycles = 2
@@ -141,17 +142,17 @@ class functional(simulation):
             sp_read_value = ""
             for bit in range(self.word_size):
                 value = parse_spice_list("timing", "v{0}.{1}ck{2}".format(dout_port.lower(),bit,check))
-                if value > 0.88 * self.vdd_voltage:
+                if value > self.v_high:
                     sp_read_value = "1" + sp_read_value
-                elif value < 0.12 * self.vdd_voltage:
+                elif value < self.v_low:
                     sp_read_value = "0" + sp_read_value
                 else:
                     error ="FAILED: {0}_{1} value {2} at time {3}n does not fall within noise margins <{4} or >{5}.".format(dout_port,
                                                                                                                             bit,
                                                                                                                             value,
                                                                                                                             eo_period,
-                                                                                                                            0.12*self.vdd_voltage,
-                                                                                                                            0.88*self.vdd_voltage)
+                                                                                                                            self.v_low,
+                                                                                                                            self.v_high)
                     return (0, error)
                     
             self.read_check.append([sp_read_value, dout_port, eo_period, check])                    
diff --git a/compiler/characterizer/simulation.py b/compiler/characterizer/simulation.py
index 46bd6c57..beca0502 100644
--- a/compiler/characterizer/simulation.py
+++ b/compiler/characterizer/simulation.py
@@ -37,6 +37,9 @@ class simulation():
         self.period = tech.spice["feasible_period"]
         self.slew = tech.spice["rise_time"]*2
         self.load = tech.spice["msflop_in_cap"]*4
+
+        self.v_high = self.vdd_voltage - tech.spice["v_threshold_typical"]
+        self.v_low = tech.spice["v_threshold_typical"]        
         self.gnd_voltage = 0
         
     def set_stimulus_variables(self):