From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Wed, 27 Feb 2019 00:12:27 +0000 (+0000)
Subject: clear STB immediately after setting, stops add1 repeating computation
X-Git-Tag: ls180-24jan2020~1827
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=262f37d15b93a473d8de4b31c0297bb130473bfd;p=ieee754fpu.git

clear STB immediately after setting, stops add1 repeating computation
---

diff --git a/src/add/fpbase.py b/src/add/fpbase.py
index 26528f62..10997be4 100644
--- a/src/add/fpbase.py
+++ b/src/add/fpbase.py
@@ -347,8 +347,8 @@ class FPOp:
         if extra is not None:
             stb = stb & extra
         return [self.v.eq(in_op.v),          # receive value
-                self.stb.eq(~stb),      # receive STB
-                in_op.ack.eq(~self.ack), # send ACK
+                self.stb.eq(stb),      # receive STB
+                in_op.ack.eq(self.ack), # send ACK
                ]
 
     def chain_from(self, in_op, extra=None):
diff --git a/src/add/test_dual.py b/src/add/test_dual.py
index 6f9d8c8e..15f5c762 100644
--- a/src/add/test_dual.py
+++ b/src/add/test_dual.py
@@ -11,6 +11,8 @@ def get_case(dut, a, b, c):
     a_ack = (yield dut.a.ack)
     assert a_ack == 0
 
+    yield dut.a.stb.eq(0)
+
     yield dut.b.v.eq(b)
     yield dut.b.stb.eq(1)
     yield
@@ -18,6 +20,8 @@ def get_case(dut, a, b, c):
     b_ack = (yield dut.b.ack)
     assert b_ack == 0
 
+    yield dut.b.stb.eq(0)
+
     yield dut.c.v.eq(c)
     yield dut.c.stb.eq(1)
     yield
@@ -25,12 +29,9 @@ def get_case(dut, a, b, c):
     c_ack = (yield dut.c.ack)
     assert c_ack == 0
 
-    while True:
-        out_z_stb = (yield dut.int_stb)
-        if not out_z_stb:
-            yield
-            continue
-        break
+    yield dut.c.stb.eq(0)
+
+    yield dut.z.ack.eq(1)
 
     while True:
         out_z_stb = (yield dut.z.stb)
@@ -41,12 +42,6 @@ def get_case(dut, a, b, c):
         out_z = yield dut.z.v
 
         yield dut.z.ack.eq(0)
-        yield dut.a.stb.eq(0)
-        yield dut.b.stb.eq(0)
-        yield dut.c.stb.eq(0)
-        yield
-        yield dut.z.ack.eq(1)
-        yield
         break
 
     return out_z