Enforce max queue depth on streaming sources

cocotbext/eth/xgmii.py

@@ -27,7 +27,7 @@ import struct
 import zlib
 
 import cocotb
-from cocotb.queue import Queue
+from cocotb.queue import Queue, QueueFull
 from cocotb.triggers import RisingEdge, Timer, First, Event
 from cocotb.utils import get_sim_time
 
@@ -154,6 +154,7 @@ class XgmiiSource(Reset):
 
         self.active = False
         self.queue = Queue()
+        self.dequeue_event = Event()
         self.current_frame = None
         self.idle_event = Event()
         self.idle_event.set()
@@ -165,6 +166,9 @@ class XgmiiSource(Reset):
         self.queue_occupancy_bytes = 0
         self.queue_occupancy_frames = 0
 
+        self.queue_occupancy_limit_bytes = -1
+        self.queue_occupancy_limit_frames = -1
+
         self.width = len(self.data)
         self.byte_width = len(self.ctrl)
 
@@ -185,6 +189,9 @@ class XgmiiSource(Reset):
         self._init_reset(reset, reset_active_level)
 
     async def send(self, frame):
+        while self.full():
+            self.dequeue_event.clear()
+            await self.dequeue_event.wait()
         frame = XgmiiFrame(frame)
         await self.queue.put(frame)
         self.idle_event.clear()
@@ -192,6 +199,8 @@ class XgmiiSource(Reset):
         self.queue_occupancy_frames += 1
 
     def send_nowait(self, frame):
+        if self.full():
+            raise QueueFull()
         frame = XgmiiFrame(frame)
         self.queue.put_nowait(frame)
         self.idle_event.clear()
@@ -204,6 +213,14 @@ class XgmiiSource(Reset):
     def empty(self):
         return self.queue.empty()
 
+    def full(self):
+        if self.queue_occupancy_limit_bytes > 0 and self.queue_occupancy_bytes > self.queue_occupancy_limit_bytes:
+            return True
+        elif self.queue_occupancy_limit_frames > 0 and self.queue_occupancy_frames > self.queue_occupancy_limit_frames:
+            return True
+        else:
+            return False
+
     def idle(self):
         return self.empty() and not self.active
 
@@ -212,6 +229,7 @@ class XgmiiSource(Reset):
             frame = self.queue.get_nowait()
             frame.sim_time_end = None
             frame.handle_tx_complete()
+        self.dequeue_event.set()
         self.idle_event.set()
         self.queue_occupancy_bytes = 0
         self.queue_occupancy_frames = 0
@@ -265,6 +283,7 @@ class XgmiiSource(Reset):
                     if not self.queue.empty():
                         # send frame
                         frame = self.queue.get_nowait()
+                        self.dequeue_event.set()
                         self.queue_occupancy_bytes -= len(frame)
                         self.queue_occupancy_frames -= 1
                         self.current_frame = frame