endpoints: add param_layout parameter (required to pass parameter data with converters and will allow logic optimizations)

doc/dataflow.rst

@@ -69,6 +69,14 @@ Accessing the endpoints is done by manipulating the signals inside the ``Source`
 * A signal object ``ack``.
 * The data payload ``payload``, which is a record with the layout given to the endpoint constructor.
 
+Endpoints can also be used to manipulate packets, this is done by setting packetized parameter to True which adds:
+
+* A signal object ``sop`` (Start Of Packet).
+* A signal object ``eop`` (End Of Packet).
+
+When used in packetized mode, packet parameters (signals that do no change for the duration of a packet) should to be declared in
+param_layout. Declaring these signals in payload_layout will works in most cases but will prevent logic optimizations.
+
 Busy signal
 ===========
 

migen/actorlib/fifo.py

@@ -11,7 +11,13 @@ class _FIFOActor(Module):
 		###
 
 		description = self.sink.description
-		fifo_layout = [("payload", description.payload_layout)]
+		fifo_layout = [
+			("payload", description.payload_layout),
+			# Note : Can be optimized by passing parameters
+			#        in another fifo. We will only have one
+			#        data per packet.
+			("param", description.param_layout)
+		]
 		if description.packetized:
 			fifo_layout += [("sop", 1), ("eop", 1)]
 
@@ -21,9 +27,11 @@ class _FIFOActor(Module):
 			self.sink.ack.eq(self.fifo.writable),
 			self.fifo.we.eq(self.sink.stb),
 			self.fifo.din.payload.eq(self.sink.payload),
+			self.fifo.din.param.eq(self.sink.param),
 
 			self.source.stb.eq(self.fifo.readable),
 			self.source.payload.eq(self.fifo.dout.payload),
+			self.source.param.eq(self.fifo.dout.param),
 			self.fifo.re.eq(self.source.ack)
 		]
 		if description.packetized:

migen/actorlib/structuring.py

@@ -66,6 +66,11 @@ class Unpack(Module):
 			cases[i] = [source.payload.raw_bits().eq(getattr(sink.payload, "chunk"+str(chunk)).raw_bits())]
 		self.comb += Case(mux, cases).makedefault()
 
+		for f in description_from.param_layout:
+			src = getattr(self.sink, f[0])
+			dst = getattr(self.source, f[0])
+			self.comb += dst.eq(src)
+
 		if description_from.packetized:
 			self.comb += [
 				source.sop.eq(sink.sop & first),
@@ -97,6 +102,11 @@ class Pack(Module):
 			load_part.eq(sink.stb & sink.ack)
 		]
 
+		for f in description_to.param_layout:
+			src = getattr(self.sink, f[0])
+			dst = getattr(self.source, f[0])
+			self.comb += dst.eq(src)
+
 		if description_to.packetized:
 			demux_last = ((demux == (n - 1)) | sink.eop)
 		else:
@@ -146,6 +156,11 @@ class Chunkerize(CombinatorialActor):
 				dst = getattr(getattr(self.source, "chunk"+str(chunk)), f[0])
 				self.comb += dst.eq(src[i*flen(src)//n:(i+1)*flen(src)//n])
 
+		for f in self.sink.description.param_layout:
+			src = getattr(self.sink, f[0])
+			dst = getattr(self.source, f[0])
+			self.comb += dst.eq(src)
+
 class Unchunkerize(CombinatorialActor):
 	def __init__(self, layout_from, n, layout_to, reverse=False):
 		if isinstance(layout_from, EndpointDescription):
@@ -168,6 +183,11 @@ class Unchunkerize(CombinatorialActor):
 				dst = getattr(self.source, f[0])
 				self.comb += dst[i*flen(dst)//n:(i+1)*flen(dst)//n].eq(src)
 
+		for f in self.sink.description.param_layout:
+			src = getattr(self.sink, f[0])
+			dst = getattr(self.source, f[0])
+			self.comb += dst.eq(src)
+
 class Converter(Module):
 	def __init__(self, layout_from, layout_to, reverse=False):
 		self.sink = Sink(layout_from)

migen/flow/actor.py

@@ -13,18 +13,24 @@ def _make_m2s(layout):
 	return r
 
 class EndpointDescription:
-	def __init__(self, payload_layout, packetized=False):
+	def __init__(self, payload_layout, param_layout=[], packetized=False):
 		self.payload_layout = payload_layout
+		self.param_layout = param_layout
 		self.packetized = packetized
 
 	def get_full_layout(self):
-		reserved = {"stb", "ack", "payload", "sop", "eop", "description"}
-		for f in self.payload_layout:
+		reserved = {"stb", "ack", "payload", "param", "sop", "eop", "description"}
+		attributed = set()
+		for f in self.payload_layout + self.param_layout:
+			if f[0] in attributed:
+				raise ValueError(f[0] + " already attributed in payload or param layout")
 			if f[0] in reserved:
 				raise ValueError(f[0] + " cannot be used in endpoint layout")
+			attributed.add(f[0])
 
 		full_layout = [
 			("payload", _make_m2s(self.payload_layout)),
+			("param", _make_m2s(self.param_layout)),
 			("stb", 1, DIR_M_TO_S),
 			("ack", 1, DIR_S_TO_M)
 		]
@@ -45,7 +51,10 @@ class _Endpoint(Record):
 		Record.__init__(self, self.description.get_full_layout())
 
 	def __getattr__(self, name):
+		try:
 			return getattr(object.__getattribute__(self, "payload"), name)
+		except:
+			return getattr(object.__getattribute__(self, "param"), name)
 
 class Source(_Endpoint):
 	def connect(self, sink):

migen/flow/plumbing.py

@@ -8,7 +8,11 @@ class Buffer(PipelinedActor):
 		self.d = Sink(layout)
 		self.q = Source(layout)
 		PipelinedActor.__init__(self, 1)
-		self.sync += If(self.pipe_ce, self.q.payload.eq(self.d.payload))
+		self.sync += \
+			If(self.pipe_ce,
+				self.q.payload.eq(self.d.payload),
+				self.q.param.eq(self.d.param)
+			)
 
 class Combinator(Module):
 	def __init__(self, layout, subrecords):
@@ -28,6 +32,7 @@ class Combinator(Module):
 		]
 		self.comb += [sink.ack.eq(self.source.ack & self.source.stb) for sink in sinks]
 		self.comb += [self.source.payload.eq(sink.payload) for sink in sinks]
+		self.comb += [self.source.param.eq(sink.param) for sink in sinks]
 
 class Splitter(Module):
 	def __init__(self, layout, subrecords):
@@ -42,6 +47,7 @@ class Splitter(Module):
 		###
 
 		self.comb += [source.payload.eq(self.sink.payload) for source in sources]
+		self.comb += [source.param.eq(self.sink.param) for source in sources]
 		already_acked = Signal(len(sources))
 		self.sync += If(self.sink.stb,
 				already_acked.eq(already_acked | Cat(*[s.ack for s in sources])),