From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Sat, 17 Aug 2019 07:06:20 +0000 (+0100)
Subject: use Cat instead of for-loops: cleans up the yosys graphviz massively
X-Git-Tag: ls180-24jan2020~522
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=a3db00e119193342217ad196f8fb1b97ce05475e;p=ieee754fpu.git

use Cat instead of for-loops: cleans up the yosys graphviz massively
---

diff --git a/src/ieee754/part_mul_add/multiply.py b/src/ieee754/part_mul_add/multiply.py
index b62f7373..f0bb95b5 100644
--- a/src/ieee754/part_mul_add/multiply.py
+++ b/src/ieee754/part_mul_add/multiply.py
@@ -171,19 +171,35 @@ class PartitionedAdder(Elaboratable):
         """Elaborate this module."""
         m = Module()
         expanded_index = 0
+        # store bits in a list, use Cat later.  graphviz is much cleaner
+        al = []
+        bl = []
+        ol = []
+        ea = []
+        eb = []
+        eo = []
+        # partition points are "breaks" (extra zeros) in what would otherwise
+        # be a massive long add.
         for i in range(self.width):
             if i in self.partition_points:
                 # add extra bit set to 0 + 0 for enabled partition points
                 # and 1 + 0 for disabled partition points
-                m.d.comb += self._expanded_a[expanded_index].eq(
-                    ~self.partition_points[i])
-                m.d.comb += self._expanded_b[expanded_index].eq(0)
+                ea.append(self._expanded_a[expanded_index])
+                al.append(~self.partition_points[i])
+                eb.append(self._expanded_b[expanded_index])
+                bl.append(C(0))
                 expanded_index += 1
-            m.d.comb += self._expanded_a[expanded_index].eq(self.a[i])
-            m.d.comb += self._expanded_b[expanded_index].eq(self.b[i])
-            m.d.comb += self.output[i].eq(
-                self._expanded_output[expanded_index])
+            ea.append(self._expanded_a[expanded_index])
+            al.append(self.a[i])
+            eb.append(self._expanded_b[expanded_index])
+            bl.append(self.b[i])
+            eo.append(self._expanded_output[expanded_index])
+            ol.append(self.output[i])
             expanded_index += 1
+        # combine above using Cat
+        m.d.comb += Cat(*ea).eq(Cat(*al))
+        m.d.comb += Cat(*eb).eq(Cat(*bl))
+        m.d.comb += Cat(*eo).eq(Cat(*ol))
         # use only one addition to take advantage of look-ahead carry and
         # special hardware on FPGAs
         m.d.comb += self._expanded_output.eq(