actorlib/structuring: add reverse parameter to Unpack and Pack

diff --git a/migen/actorlib/structuring.py b/migen/actorlib/structuring.py
index e671fed05705dac6378fdf4a512ecc5d6ca352b6..d2f690b9c176069f79d245e460ce37cdda31016d 100644 (file)
--- a/migen/actorlib/structuring.py
+++ b/migen/actorlib/structuring.py
@@ -12,7 +12,7 @@ class Cast(CombinatorialActor):
                self.sink = Sink(_rawbits_layout(layout_from))
                self.source = Source(_rawbits_layout(layout_to))
                CombinatorialActor.__init__(self)
-       
+
                ###
 
                sigs_from = self.sink.payload.flatten()
@@ -29,11 +29,11 @@ def pack_layout(l, n):
        return [("chunk"+str(i), l) for i in range(n)]
 
 class Unpack(Module):
-       def __init__(self, n, layout_to):
+       def __init__(self, n, layout_to, reverse=False):
                self.sink = Sink(pack_layout(layout_to, n))
                self.source = Source(layout_to)
                self.busy = Signal()
-       
+
                ###
 
                mux = Signal(max=n)
@@ -54,24 +54,26 @@ class Unpack(Module):
                ]
                cases = {}
                for i in range(n):
-                       cases[i] = [self.source.payload.raw_bits().eq(getattr(self.sink.payload, "chunk"+str(i)).raw_bits())]
+                       chunk = n-i-1 if reverse else i
+                       cases[i] = [self.source.payload.raw_bits().eq(getattr(self.sink.payload, "chunk"+str(chunk)).raw_bits())]
                self.comb += Case(mux, cases).makedefault()
 
 class Pack(Module):
-       def __init__(self, layout_from, n):
+       def __init__(self, layout_from, n, reverse=False):
                self.sink = Sink(layout_from)
                self.source = Source(pack_layout(layout_from, n))
                self.busy = Signal()
-       
+
                ###
 
                demux = Signal(max=n)
-               
+
                load_part = Signal()
                strobe_all = Signal()
                cases = {}
                for i in range(n):
-                       cases[i] = [getattr(self.source.payload, "chunk"+str(i)).raw_bits().eq(self.sink.payload.raw_bits())]
+                       chunk = n-i-1 if reverse else i
+                       cases[i] = [getattr(self.source.payload, "chunk"+str(chunk)).raw_bits().eq(self.sink.payload.raw_bits())]
                self.comb += [
                        self.busy.eq(strobe_all),
                        self.sink.ack.eq(~strobe_all | self.source.ack),