flow: actor class

diff --git a/migen/flow/__init__.py b/migen/flow/__init__.py
new file mode 100644 (file)
index 0000000..e69de29

diff --git a/migen/flow/actor.py b/migen/flow/actor.py
new file mode 100644 (file)
index 0000000..774a922
--- /dev/null
+++ b/migen/flow/actor.py
@@ -0,0 +1,114 @@
+from migen.fhdl.structure import *
+from migen.corelogic.optree import optree
+
+class SchedulingModel:
+       COMBINATORIAL, SEQUENTIAL, PIPELINE, DYNAMIC = range(6)
+       
+       def __init__(self, model, latency=1):
+               self.model = model
+               self.latency = latency
+       
+       def __str__(self):
+               if self.model == SchedulingModel.COMBINATORIAL:
+                       return "<SchedulingModel: COMBINATORIAL>"
+               elif self.model == SchedulingModel.SEQUENTIAL:
+                       return "<SchedulingModel: SEQUENTIAL({0})>".format(self.latency)
+               elif self.model == SchedulingModel.PIPELINE:
+                       return "<SchedulingModel: PIPELINE({0})>".format(self.latency)
+               elif self.model == SchedulingModel.DYNAMIC:
+                       return "<SchedulingModel: DYNAMIC>"
+               else:
+                       raise AttributeError
+
+class Sink:
+       def __init__(self, actor, token):
+               self.actor = actor
+               self.token = token
+               self.stb_i = Signal()
+               self.ack_o = Signal()
+
+class Source:
+       def __init__(self, actor, token):
+               self.actor = actor
+               self.token = token
+               self.stb_o = Signal()
+               self.ack_i = Signal()
+
+def _control_fragment_comb(l_stb_i, l_ack_o, l_stb_o, l_ack_i):
+       en = Signal()
+       comb = [en.eq(optree('&', l_stb_i + l_ack_i))]
+       comb += [o.eq(en) for o in l_ack_o + l_stb_o]
+       return Fragment(comb)
+
+def _control_fragment_seq(latency, l_stb_i, l_ack_o, l_stb_o, l_ack_i, trigger):
+       ready = Signal()
+       timer = Signal(BV(bits_for(latency)))
+       comb = [ready.eq(timer == 0))]
+       sync = [
+               If(trigger,
+                       timer.eq(latency)
+               ).Elif(~ready,
+                       timer.eq(timer - 1)
+               )
+       ]
+       
+       nsources = len(l_stb_o)
+       mask = Signal(BV(nsources))
+       sync.append(If(trigger, mask.eq(0)).Else(mask.eq(mask | Cat(*l_ack_i))))
+
+       comb.append(Cat(*l_stb_o).eq(Replicate(len(l_stb_o), ready) & ~mask))
+       comb.append(Cat(*l_ack_o).eq(Replicate(len(l_ack_o), trigger)))
+       
+       stb_all = Signal()
+       comb.append(stb_all.eq(optree('&', l_stb_i)))
+       comb.append(trigger.eq(ready & stb_all & ((mask | Cat(*l_ack_i)) == Replicate(nsources, 1))))
+
+       return Fragment(comb, sync)
+
+def _control_fragment_pipe(latency, l_stb_i, l_ack_o, l_stb_o, l_ack_i, pipe_ce):
+       stb_all = Signal()
+       comb = [stb_all.eq(optree('&', l_stb_i))]
+       valid = Signal(BV(latency))
+       if latency > 1:
+               sync = [If(pipe_ce, valid.eq(Cat(stb_all, valid[1:])))]
+       else:
+               sync = [If(pipe_ce, valid.eq(stb_all))]
+       last_valid = valid[latency-1]
+       
+       nsources = len(l_stb_o)
+       mask = Signal(BV(nsources))
+       sync.append(If(pipe_ce, mask.eq(0)).Else(mask.eq(mask | Cat(*l_ack_i))))
+       
+       comb.append(Cat(*l_stb_o).eq(Replicate(len(l_stb_o), last_valid) & ~mask))
+       comb.append(Cat(*l_ack_o).eq(Replicate(len(l_ack_o), pipe_ce)))
+       
+       comb.append(pipe_ce.eq(~last_valid | ((mask | Cat(*l_ack_i)) == Replicate(nsources, 1))))
+       
+       return Fragment(comb, sync)
+
+class Actor:
+       def __init__(self, scheduling_model, sinks, sources):
+               self.scheduling_model = scheduling_model
+               self.sinks = sinks
+               self.sources = sources
+               if self.scheduling_model.model == SEQUENTIAL:
+                       self.trigger = Signal()
+               elif self.scheduling_model.model == PIPELINE:
+                       self.pipe_ce = Signal()
+       
+       def get_control_fragment():
+               l_stb_i = [e.stb_i for e in self.sinks]
+               l_ack_o = [e.ack_o for e in self.sinks]
+               l_stb_o = [e.stb_o for e in self.sources]
+               l_ack_i = [e.ack_i for e in self.sources]
+               if self.scheduling_model.model == COMBINATORIAL:
+                       return _control_fragment_comb(l_stb_i, l_ack_o, l_stb_o, l_ack_i)
+               elif self.scheduling_model.model == SEQUENTIAL:
+                       return _control_fragment_seq(self.scheduling_model.latency, l_stb_i, l_ack_o, l_stb_o, l_ack_i, self.trigger)
+               elif self.scheduling_model.model == PIPELINE:
+                       return _control_fragment_pipe(self.scheduling_model.latency, l_stb_i, l_ack_o, l_stb_o, l_ack_i, self.pipe_ce)
+               elif self.scheduling_model.model == DYNAMIC:
+                       raise NotImplementedError("Actor classes with dynamic scheduling must overload get_control_fragment")
+       
+       def get_process_fragment():
+               raise NotImplementedError("Actor classes must overload get_process_fragment")