From: Michael Nolan <mtnolan2640@gmail.com>
Date: Wed, 12 Feb 2020 19:12:26 +0000 (-0500)
Subject: Reduce width of b operand to minimum size needed
X-Git-Tag: ls180-24jan2020~185
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=7e46159e14f46b6c3c192ee2342b8c202f6268af;p=ieee754fpu.git

Reduce width of b operand to minimum size needed
---

diff --git a/src/ieee754/part_shift/part_shift_dynamic.py b/src/ieee754/part_shift/part_shift_dynamic.py
index 2eb6a499..97be1118 100644
--- a/src/ieee754/part_shift/part_shift_dynamic.py
+++ b/src/ieee754/part_shift/part_shift_dynamic.py
@@ -71,7 +71,9 @@ class PartitionedDynamicShift(Elaboratable):
             start = 0
             for j, a in enumerate(a_intervals):
                 end = keys[i]
-                comb += matrix[i][j].eq(a << b)
+                result_width = matrix[i][j].width
+                bwidth = math.ceil(math.log2(result_width + 1))
+                comb += matrix[i][j].eq(a << b[:bwidth])
                 start = end
 
         # now create a switch statement which sums the relevant partial results