From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Mon, 18 Feb 2019 11:55:33 +0000 (+0000)
Subject: fix a - b = zero by adding special case
X-Git-Tag: ls180-24jan2020~1914
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=40e7f99d07484253630d09a339547f2db1ddd4ce;p=ieee754fpu.git

fix a - b = zero by adding special case
---

diff --git a/src/add/nmigen_add_experiment.py b/src/add/nmigen_add_experiment.py
index a751ea2e..7d9ccb71 100644
--- a/src/add/nmigen_add_experiment.py
+++ b/src/add/nmigen_add_experiment.py
@@ -88,6 +88,10 @@ class FPADD(FPBase):
                     m.next = "put_z"
                     m.d.sync += z.create(a.s, a.e, a.m[3:-1])
 
+                with m.Elif((a.s != b.s) & (a.m == b.m) & (a.e == b.e)):
+                    m.next = "put_z"
+                    m.d.sync += z.zero(0)
+
                 # Denormalised Number checks
                 with m.Else():
                     m.next = "align"