51 lines
1.3 KiB
Python
51 lines
1.3 KiB
Python
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from migen.fhdl import visit as fhdl
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from migen.corelogic.fsm import FSM
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class AbstractNextState:
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def __init__(self, target_state):
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self.target_state = target_state
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# entry state is first state returned
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class StateAssembler:
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def __init__(self):
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self.states = []
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self.exit_states = []
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def assemble(self, n_states, n_exit_states):
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self.states += n_states
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for exit_state in self.exit_states:
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exit_state.insert(0, AbstractNextState(n_states[0]))
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self.exit_states = n_exit_states
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def ret(self):
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return self.states, self.exit_states
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# like list.index, but using "is" instead of comparison
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def _index_is(l, x):
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for i, e in enumerate(l):
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if e is x:
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return i
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class _LowerAbstractNextState(fhdl.NodeTransformer):
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def __init__(self, fsm, states, stnames):
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self.fsm = fsm
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self.states = states
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self.stnames = stnames
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def visit_unknown(self, node):
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if isinstance(node, AbstractNextState):
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index = _index_is(self.states, node.target_state)
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estate = getattr(self.fsm, self.stnames[index])
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return self.fsm.next_state(estate)
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else:
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return node
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def implement_fsm(states):
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stnames = ["S" + str(i) for i in range(len(states))]
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fsm = FSM(*stnames)
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lans = _LowerAbstractNextState(fsm, states, stnames)
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for i, state in enumerate(states):
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actions = lans.visit(state)
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fsm.act(getattr(fsm, stnames[i]), *actions)
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return fsm
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