litex/migen/flow/actor.py

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from migen.fhdl.structure import *
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from migen.corelogic.misc import optree
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from migen.corelogic.record import *
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class SchedulingModel:
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COMBINATORIAL, SEQUENTIAL, PIPELINE, DYNAMIC = range(4)
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def __init__(self, model, latency=1):
self.model = model
self.latency = latency
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def __repr__(self):
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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
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class Endpoint:
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def __init__(self, token):
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self.token = token
if isinstance(self, Sink):
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self.stb = Signal(name="stb_i")
self.ack = Signal(name="ack_o")
else:
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self.stb = Signal(name="stb_o")
self.ack = Signal(name="ack_i")
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def token_signal(self):
sigs = self.token.flatten()
assert(len(sigs) == 1)
return sigs[0]
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def __hash__(self):
return id(self)
def __repr__(self):
return "<Endpoint " + str(self.token) + ">"
class Sink(Endpoint):
def __repr__(self):
return "<Sink " + str(self.token) + ">"
class Source(Endpoint):
def __repr__(self):
return "<Source " + str(self.token) + ">"
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def _control_fragment_comb(stb_i, ack_o, stb_o, ack_i, busy):
return Fragment([stb_o.eq(stb_i), ack_o.eq(ack_i), busy.eq(0)])
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def _control_fragment_seq(latency, stb_i, ack_o, stb_o, ack_i, busy, trigger):
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ready = Signal()
timer = Signal(BV(bits_for(latency)))
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comb = [ready.eq(timer == 0)]
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sync = [
If(trigger,
timer.eq(latency)
).Elif(~ready,
timer.eq(timer - 1)
)
]
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mask = Signal()
comb += [
stb_o.eq(ready & mask),
trigger.eq(stb_i & (ack_i | ~mask) & ready),
ack_o.eq(trigger),
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busy.eq(~ready)
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]
sync += [
If(trigger, mask.eq(1)),
If(stb_o & ack_i, mask.eq(0))
]
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return Fragment(comb, sync)
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def _control_fragment_pipe(latency, stb_i, ack_o, stb_o, ack_i, busy, pipe_ce):
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valid = Signal(BV(latency))
if latency > 1:
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sync = [If(pipe_ce, valid.eq(Cat(stb_i, valid[:latency-1])))]
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else:
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sync = [If(pipe_ce, valid.eq(stb_i))]
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last_valid = valid[latency-1]
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comb = [
pipe_ce.eq(ack_i | ~last_valid),
ack_o.eq(pipe_ce),
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stb_o.eq(last_valid),
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busy.eq(optree("|", [valid[i] for i in range(latency)]))
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]
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return Fragment(comb, sync)
class Actor:
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def __init__(self, scheduling_model, *endpoint_descriptions, endpoints=None):
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self.scheduling_model = scheduling_model
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if endpoints is None:
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self.endpoints = {}
for desc in endpoint_descriptions:
# desc: (name, Sink/Source, token layout or existing record)
if isinstance(desc[2], Record):
token = desc[2]
else:
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token = Record(desc[2])
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ep = desc[1](token)
self.endpoints[desc[0]] = ep
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else:
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self.endpoints = endpoints
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self.busy = Signal()
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if self.scheduling_model.model == SchedulingModel.SEQUENTIAL:
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self.trigger = Signal()
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elif self.scheduling_model.model == SchedulingModel.PIPELINE:
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self.pipe_ce = Signal()
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def token(self, ep):
return self.endpoints[ep].token
def filter_endpoints(self, cl):
return [k for k, v in self.endpoints.items() if isinstance(v, cl)]
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def sinks(self):
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return self.filter_endpoints(Sink)
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def sources(self):
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return self.filter_endpoints(Source)
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def get_control_fragment(self):
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def get_single_ep(l):
if len(l) != 1:
raise ValueError("Actors with automatic control fragment must have exactly one sink and one source. Consider using plumbing actors.")
return self.endpoints[l[0]]
sink = get_single_ep(self.sinks())
source = get_single_ep(self.sources())
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stb_i = sink.stb
ack_o = sink.ack
stb_o = source.stb
ack_i = source.ack
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if self.scheduling_model.model == SchedulingModel.COMBINATORIAL:
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return _control_fragment_comb(stb_i, ack_o, stb_o, ack_i, self.busy)
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elif self.scheduling_model.model == SchedulingModel.SEQUENTIAL:
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return _control_fragment_seq(self.scheduling_model.latency, stb_i, ack_o, stb_o, ack_i, self.busy, self.trigger)
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elif self.scheduling_model.model == SchedulingModel.PIPELINE:
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return _control_fragment_pipe(self.scheduling_model.latency, stb_i, ack_o, stb_o, ack_i, self.busy, self.pipe_ce)
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elif self.scheduling_model.model == SchedulingModel.DYNAMIC:
raise NotImplementedError("Actor classes with dynamic scheduling must overload get_control_fragment or get_fragment")
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def get_process_fragment(self):
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raise NotImplementedError("Actor classes must overload get_process_fragment")
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def get_fragment(self):
return self.get_control_fragment() + self.get_process_fragment()
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def __repr__(self):
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return "<" + self.__class__.__name__ + " " + repr(self.scheduling_model) + " " + repr(self.sinks()) + " " + repr(self.sources()) + ">"
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def get_conn_fragment(source, sink):
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assert isinstance(source, Source)
assert isinstance(sink, Sink)
assert sink.token.compatible(source.token)
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sigs_source = source.token.flatten()
sigs_sink = sink.token.flatten()
comb = [
source.ack.eq(sink.ack),
sink.stb.eq(source.stb),
Cat(*sigs_sink).eq(Cat(*sigs_source))
]
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return Fragment(comb)