From a6acfb9a37e121f5458fd1bf6139f85e7114e503 Mon Sep 17 00:00:00 2001
From: Florent Kermarrec <florent@enjoy-digital.fr>
Date: Wed, 7 Sep 2022 08:58:51 +0200
Subject: [PATCH] stream/Buffer: Integrate PipeValid/PipeReady (both
 configurable) and add tests.

Allow selecting pipelining of valid/data or/and ready and creating a full Skid Buffer
(Pipeline of both valid/data and ready).
---
 litex/soc/interconnect/stream.py | 27 ++++++++++++++++++++++++++-
 test/test_stream.py              | 12 ++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/litex/soc/interconnect/stream.py b/litex/soc/interconnect/stream.py
index 1543cdfaa..dde5e23be 100644
--- a/litex/soc/interconnect/stream.py
+++ b/litex/soc/interconnect/stream.py
@@ -766,7 +766,32 @@ class PipeReady(Module):
 
 # Buffer -------------------------------------------------------------------------------------------
 
-class Buffer(PipeValid): pass # FIXME: Replace Buffer with PipeValid in codebase?
+class Buffer(Module):
+    """Pipe valid/payload and/or ready to cut timing path"""
+    def __init__(self, layout, pipe_valid=True, pipe_ready=False):
+        self.sink   = sink   = Endpoint(layout)
+        self.source = source = Endpoint(layout)
+
+        # # #
+
+        pipeline = []
+
+        # Pipe Valid (Optional).
+        if pipe_valid:
+            self.submodules.pipe_valid = PipeValid(layout)
+            pipeline.append(self.pipe_valid)
+
+        # Pipe Ready (Optional).
+        if pipe_ready:
+            self.submodules.pipe_ready = PipeReady(layout)
+            pipeline.append(self.pipe_ready)
+
+        # Buffer Pipeline.
+        self.submodules.pipeline = Pipeline(
+            sink,
+            *pipeline,
+            source
+        )
 
 # Cast ---------------------------------------------------------------------------------------------
 
diff --git a/test/test_stream.py b/test/test_stream.py
index 7da893850..d2865b7d5 100644
--- a/test/test_stream.py
+++ b/test/test_stream.py
@@ -50,3 +50,15 @@ class TestStream(unittest.TestCase):
     def test_pipe_ready(self):
         dut = PipeReady([("data", 8)])
         self.pipe_test(dut)
+
+    def test_buffer_valid(self):
+        dut = Buffer([("data", 8)], pipe_valid=True, pipe_ready=False)
+        self.pipe_test(dut)
+
+    def test_buffer_ready(self):
+        dut = Buffer([("data", 8)], pipe_valid=False, pipe_ready=True)
+        self.pipe_test(dut)
+
+    def test_buffer_valid_ready(self):
+        dut = Buffer([("data", 8)], pipe_valid=True, pipe_ready=True)
+        self.pipe_test(dut)