simulation: Add cocotb python library for XLS

The library contains XLSChannel, XLSChannelDriver and XLSChannelMonitor classes.

* XLSChannel - provides a mechanism for wrapping all signals related to XLS channels into one object.
* XLSChannelDriver - may be used to send data to XLS channel
* XLSChannelMonitor - may be used to monitor transaction taking place in XLS Channel

Internal-tag: [#46586]
Signed-off-by: Robert Winkler <rwinkler@antmicro.com>

xls/simulation/cocotb/BUILD

@@ -0,0 +1,30 @@
+# Copyright 2023 The XLS Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+load("@xls_pip_deps//:requirements.bzl", "requirement")
+
+package(
+    default_visibility = ["//xls:xls_public"],
+    licenses = ["notice"],  # Apache 2.0
+)
+
+py_library(
+    name = "cocotb_xls",
+    srcs = ["cocotb_xls.py"],
+    imports = ["."],
+    deps = [
+        requirement("cocotb"),
+        requirement("cocotb_bus"),
+    ],
+)

xls/simulation/cocotb/cocotb_xls.py

@@ -0,0 +1,80 @@
+# Copyright 2023 The XLS Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from typing import Any, Sequence, Union
+
+import cocotb
+from cocotb.binary import BinaryValue
+from cocotb.handle import SimHandleBase
+from cocotb.triggers import RisingEdge
+from cocotb_bus.bus import Bus
+from cocotb_bus.drivers import BusDriver
+from cocotb_bus.monitors import BusMonitor
+
+Transaction = Union[BinaryValue, Sequence[BinaryValue]]
+
+XLS_CHANNEL_SIGNALS = ["data", "rdy", "vld"]
+XLS_CHANNEL_OPTIONAL_SIGNALS = []
+
+
+class XLSChannel(Bus):
+  _signals = XLS_CHANNEL_SIGNALS
+  _optional_signals = XLS_CHANNEL_OPTIONAL_SIGNALS
+
+  def __init__(self, entity, name, **kwargs: Any):
+    super().__init__(entity, name, self._signals, self._optional_signals, **kwargs)
+
+
+class XLSChannelDriver(BusDriver):
+  _signals = XLS_CHANNEL_SIGNALS
+  _optional_signals = XLS_CHANNEL_OPTIONAL_SIGNALS
+
+  def __init__(self, entity: SimHandleBase, name: str, clock: SimHandleBase, **kwargs: Any):
+    BusDriver.__init__(self, entity, name, clock, **kwargs)
+
+    self.bus.data.setimmediatevalue(0)
+    self.bus.vld.setimmediatevalue(0)
+
+  async def _driver_send(self, transaction: Transaction, sync: bool = True, **kwargs: Any) -> None:
+    if sync:
+      await RisingEdge(self.clock)
+
+    data_to_send = (transaction if isinstance(transaction, Sequence) else [transaction])
+
+    for word in data_to_send:
+      self.bus.vld.value = 1
+      self.bus.data.value = word
+
+      while True:
+        await RisingEdge(self.clock)
+        if self.bus.rdy.value:
+          break
+
+      self.bus.vld.value = 0
+
+
+class XLSChannelMonitor(BusMonitor):
+  _signals = XLS_CHANNEL_SIGNALS
+  _optional_signals = XLS_CHANNEL_OPTIONAL_SIGNALS
+
+  def __init__(self, entity: SimHandleBase, name: str, clock: SimHandleBase, **kwargs: Any):
+    BusMonitor.__init__(self, entity, name, clock, **kwargs)
+
+  @cocotb.coroutine
+  async def _monitor_recv(self) -> None:
+    while True:
+      await RisingEdge(self.clock)
+      if self.bus.rdy.value:
+        vec = self.bus.data.value
+        self._recv(vec)