From 8157b28da4fc1a74f8b0e3491625f5efa8e87b44 Mon Sep 17 00:00:00 2001
From: whitequark <cz@m-labs.hk>
Date: Mon, 23 Sep 2019 08:45:58 +0000
Subject: [PATCH] lib.fifo: make simulation read() and write() functions
 compat-only.

These functions were originally changed in 3ed51938, in an attempt
to make them take one cycle instead of two. However, this does not
actually work because of drawbacks of the simulator interface.

Avoid committing to any specific implementation for now, and instead
make them compat-only extensions.
---
 nmigen/compat/genlib/fifo.py | 24 +++++++++++++++++++++++-
 nmigen/lib/fifo.py           | 17 -----------------
 nmigen/test/test_lib_fifo.py | 36 ------------------------------------
 3 files changed, 23 insertions(+), 54 deletions(-)

diff --git a/nmigen/compat/genlib/fifo.py b/nmigen/compat/genlib/fifo.py
index 4e412d3..c7d8c36 100644
--- a/nmigen/compat/genlib/fifo.py
+++ b/nmigen/compat/genlib/fifo.py
@@ -1,4 +1,4 @@
-from ...tools import deprecated
+from ...tools import deprecated, extend
 from ...lib.fifo import FIFOInterface as NativeFIFOInterface, \
   SyncFIFO, SyncFIFOBuffered, AsyncFIFO, AsyncFIFOBuffered
 
@@ -14,3 +14,25 @@ class CompatFIFOInterface(NativeFIFOInterface):
 
 
 _FIFOInterface = CompatFIFOInterface
+
+
+@extend(NativeFIFOInterface)
+def read(self):
+    """Read method for simulation."""
+    assert (yield self.r_rdy)
+    value = (yield self.r_data)
+    yield self.r_en.eq(1)
+    yield
+    yield self.r_en.eq(0)
+    yield
+    return value
+
+@extend(NativeFIFOInterface)
+def write(self, data):
+    """Write method for simulation."""
+    assert (yield self.w_rdy)
+    yield self.w_data.eq(data)
+    yield self.w_en.eq(1)
+    yield
+    yield self.w_en.eq(0)
+    yield
diff --git a/nmigen/lib/fifo.py b/nmigen/lib/fifo.py
index 638a77e..9be6003 100644
--- a/nmigen/lib/fifo.py
+++ b/nmigen/lib/fifo.py
@@ -73,23 +73,6 @@ class FIFOInterface:
         self.r_rdy  = Signal() # not empty
         self.r_en   = Signal()
 
-    def read(self):
-        """Read method for simulation."""
-        assert (yield self.r_rdy)
-        yield self.r_en.eq(1)
-        yield
-        value = (yield self.r_data)
-        yield self.r_en.eq(0)
-        return value
-
-    def write(self, data):
-        """Write method for simulation."""
-        assert (yield self.w_rdy)
-        yield self.w_data.eq(data)
-        yield self.w_en.eq(1)
-        yield
-        yield self.w_en.eq(0)
-
     # TODO(nmigen-0.2): move this to nmigen.compat and make it a deprecated extension
     @property
     @deprecated("instead of `fifo.din`, use `fifo.w_data`")
diff --git a/nmigen/test/test_lib_fifo.py b/nmigen/test/test_lib_fifo.py
index 9a8c9c1..93ad95b 100644
--- a/nmigen/test/test_lib_fifo.py
+++ b/nmigen/test/test_lib_fifo.py
@@ -5,42 +5,6 @@ from ..back.pysim import *
 from ..lib.fifo import *
 
 
-class FIFOSmokeTestCase(FHDLTestCase):
-    def assertSyncFIFOWorks(self, fifo, xfrm=lambda x: x):
-        with Simulator(xfrm(Fragment.get(fifo, None)), vcd_file=open("test.vcd", "w")) as sim:
-            sim.add_clock(1e-6)
-            def process():
-                yield from fifo.write(1)
-                yield from fifo.write(2)
-                while not (yield fifo.r_rdy):
-                    yield
-                if not fifo.fwft:
-                    yield fifo.r_en.eq(1)
-                yield
-                self.assertEqual((yield from fifo.read()), 1)
-                self.assertEqual((yield from fifo.read()), 2)
-            sim.add_sync_process(process)
-            sim.run()
-
-    def assertAsyncFIFOWorks(self, fifo):
-        self.assertSyncFIFOWorks(fifo, xfrm=DomainRenamer({"read": "sync", "write": "sync"}))
-
-    def test_sync_fwft(self):
-        self.assertSyncFIFOWorks(SyncFIFO(width=8, depth=4, fwft=True))
-
-    def test_sync_not_fwft(self):
-        self.assertSyncFIFOWorks(SyncFIFO(width=8, depth=4, fwft=False))
-
-    def test_sync_buffered(self):
-        self.assertSyncFIFOWorks(SyncFIFOBuffered(width=8, depth=4))
-
-    def test_async(self):
-        self.assertAsyncFIFOWorks(AsyncFIFO(width=8, depth=4))
-
-    def test_async_buffered(self):
-        self.assertAsyncFIFOWorks(AsyncFIFOBuffered(width=8, depth=3))
-
-
 class FIFOModel(Elaboratable, FIFOInterface):
     """
     Non-synthesizable first-in first-out queue, implemented naively as a chain of registers.
-- 
2.30.2