From 7d0e179a035e4f9d8517250d4737d5dce169647b Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sebastien@milkymist.org>
Date: Wed, 20 Jun 2012 16:35:01 +0200
Subject: [PATCH] actorlib: structuring (untested)

---
 migen/actorlib/structuring.py | 90 +++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 migen/actorlib/structuring.py

diff --git a/migen/actorlib/structuring.py b/migen/actorlib/structuring.py
new file mode 100644
index 000000000..dff402780
--- /dev/null
+++ b/migen/actorlib/structuring.py
@@ -0,0 +1,90 @@
+from migen.fhdl.structure import *
+from migen.flow.actor import *
+
+class Cast(CombinatorialActor):
+	def __init__(self, layout_from, layout_to):
+		super().__init__(
+			("sink", Sink, layout_from),
+			("source", Source, layout_to))
+	
+	def get_process_fragment(self):
+		sigs_from = self.token("sink").flatten()
+		sigs_to = self.token("source").flatten()
+		if sum(len(s) for s in sigs_from) != sum(len(s) for s in sigs_to):
+			raise TypeError
+		return Fragment([
+			Cat(*sigs_to).eq(Cat(*sigs_from))
+		])
+
+class Chop(Actor):
+	def __init__(self, n, layout_to):
+		self.n = n
+		layout_from = [("chunk{0}".format(i), layout_to)
+			for i in range(self.n)]
+		super().__init__(
+			("sink", Sink, layout_from),
+			("source", Source, layout_to))
+	
+	def get_fragment(self):
+		muxbits = bits_for(self.n-1)
+		mux = Signal(BV(muxbits))
+		last = Signal()
+		comb = [
+			last.eq(mux == (self.n-1)),
+			self.endpoints["source"].stb.eq(self.endpoints["sink"].stb),
+			self.endpoints["sink"].ack.eq(last & self.endpoints["source"].ack)
+		]
+		sync = [
+			If(self.endpoints["source"].stb & self.endpoints["source"].ack,
+				If(last,
+					mux.eq(0)
+				).Else(
+					mux.eq(mux + 1)
+				)
+			)
+		]
+		cases = [(Constant(i, BV(muxbits)),
+			Cat(*self.token("source").flatten()).eq(*self.token("sink").subrecord("chunk{0}".format(i)).flatten()))
+			for i in range(self.n)]
+		cases[-1][0] = Default()
+		comb.append(Case(mux, *cases))
+		return Fragment(comb, sync)
+
+class Pack(Actor):
+	def __init__(self, layout_from, n):
+		self.n = n
+		layout_to = [("chunk{0}".format(i), layout_from)
+			for i in range(self.n)]
+		super().__init__(
+			("sink", Sink, layout_from),
+			("source", Source, layout_to))
+	
+	def get_fragment(self):
+		demuxbits = bits_for(self.n-1)
+		demux = Signal(BV(demuxbits))
+		
+		load_part = Signal()
+		strobe_all = Signal()
+		cases = [(Constant(i, BV(demuxbits)),
+			Cat(*self.token("source").subrecord("chunk{0}".format(i)).flatten()).eq(*self.token("sink").flatten())
+			for i in range(self.n)]
+		comb = [
+			self.endpoints["sink"].ack.eq(~strobe_all | self.endpoints["source"].ack),
+			self.endpoints["source"].stb.eq(strobe_all),
+			load_part.eq(self.endpoints["sink"].stb & self.endpoints["sink"].ack)
+		]
+		sync = [
+			If(self.endpoints["source"].ack,
+				strobe_all.eq(0)
+			),
+			If(load_part,
+				Case(demux, *cases),
+				If(demux == (self.n - 1),
+					demux.eq(0),
+					strobe_all.eq(1)
+				).Else(
+					demux.eq(demux + 1)
+				)
+			)
+		]
+		return Fragment(comb, sync)