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Sebastien Bourdeauducq
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Jun 25, 2013
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Original file line number | Diff line number | Diff line change |
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@@ -1,14 +1,14 @@ | ||
from migen.fhdl.std import * | ||
from migen.fhdl import verilog | ||
from migen.genlib.fsm import FSM | ||
from migen.genlib.fsm import FSM, NextState | ||
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class Example(Module): | ||
def __init__(self): | ||
self.s = Signal() | ||
myfsm = FSM("FOO", "BAR") | ||
myfsm = FSM() | ||
self.submodules += myfsm | ||
myfsm.act(myfsm.FOO, self.s.eq(1), myfsm.next_state(myfsm.BAR)) | ||
myfsm.act(myfsm.BAR, self.s.eq(0), myfsm.next_state(myfsm.FOO)) | ||
myfsm.act("FOO", self.s.eq(1), NextState("BAR")) | ||
myfsm.act("BAR", self.s.eq(0), NextState("FOO")) | ||
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example = Example() | ||
print(verilog.convert(example, {example.s})) |
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Original file line number | Diff line number | Diff line change |
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@@ -1,41 +1,73 @@ | ||
from collections import OrderedDict | ||
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from migen.fhdl.std import * | ||
from migen.fhdl.module import FinalizeError | ||
from migen.fhdl.visit import NodeTransformer | ||
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class FSM: | ||
def __init__(self, *states, delayed_enters=[]): | ||
nstates = len(states) + sum([d[2] for d in delayed_enters]) | ||
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self._state = Signal(max=nstates) | ||
self._next_state = Signal(max=nstates) | ||
for n, state in enumerate(states): | ||
setattr(self, state, n) | ||
self.actions = [[] for i in range(len(states))] | ||
class AnonymousState: | ||
pass | ||
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# do not use namedtuple here as it inherits tuple | ||
# and the latter is used elsewhere in FHDL | ||
class NextState: | ||
def __init__(self, state): | ||
self.state = state | ||
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class _LowerNextState(NodeTransformer): | ||
def __init__(self, next_state_signal, encoding, aliases): | ||
self.next_state_signal = next_state_signal | ||
self.encoding = encoding | ||
self.aliases = aliases | ||
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for name, target, delay in delayed_enters: | ||
target_state = getattr(self, target) | ||
if delay: | ||
name_state = len(self.actions) | ||
setattr(self, name, name_state) | ||
for i in range(delay-1): | ||
self.actions.append([self.next_state(name_state+i+1)]) | ||
self.actions.append([self.next_state(target_state)]) | ||
else: | ||
# alias | ||
setattr(self, name, target_state) | ||
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def reset_state(self, state): | ||
self._state.reset = state | ||
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def next_state(self, state): | ||
return self._next_state.eq(state) | ||
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def visit_unknown(self, node): | ||
if isinstance(node, NextState): | ||
try: | ||
actual_state = self.aliases[node.state] | ||
except KeyError: | ||
actual_state = node.state | ||
return self.next_state_signal.eq(self.encoding[actual_state]) | ||
else: | ||
return node | ||
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class FSM(Module): | ||
def __init__(self): | ||
self.actions = OrderedDict() | ||
self.state_aliases = dict() | ||
self.reset_state = None | ||
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def act(self, state, *statements): | ||
if self.finalized: | ||
raise FinalizeError | ||
if state not in self.actions: | ||
self.actions[state] = [] | ||
self.actions[state] += statements | ||
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def delayed_enter(self, name, target, delay): | ||
if self.finalized: | ||
raise FinalizeError | ||
if delay: | ||
state = name | ||
for i in range(delay): | ||
if i == delay - 1: | ||
next_state = target | ||
else: | ||
next_state = AnonymousState() | ||
self.act(state, NextState(next_state)) | ||
state = next_state | ||
else: | ||
self.state_aliases[name] = target | ||
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def get_fragment(self): | ||
cases = dict((s, a) for s, a in enumerate(self.actions) if a) | ||
comb = [ | ||
self._next_state.eq(self._state), | ||
Case(self._state, cases) | ||
def do_finalize(self): | ||
nstates = len(self.actions) | ||
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self.encoding = dict((s, n) for n, s in enumerate(self.actions.keys())) | ||
self.state = Signal(max=nstates) | ||
self.next_state = Signal(max=nstates) | ||
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lns = _LowerNextState(self.next_state, self.encoding, self.state_aliases) | ||
cases = dict((self.encoding[k], lns.visit(v)) for k, v in self.actions.items() if v) | ||
self.comb += [ | ||
self.next_state.eq(self.state), | ||
Case(self.state, cases) | ||
] | ||
sync = [self._state.eq(self._next_state)] | ||
return Fragment(comb, sync) | ||
self.sync += self.state.eq(self.next_state) |
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