actorlib: structuring (untested)

diff --git a/migen/actorlib/structuring.py b/migen/actorlib/structuring.py
new file mode 100644 (file)
index 0000000..dff4027
--- /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)