44 lines
1.3 KiB
Python
44 lines
1.3 KiB
Python
from migen.fhdl.structure import *
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class FSM:
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def __init__(self, *states, delayed_enters=[]):
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nstates = len(states) + sum([d[2] for d in delayed_enters])
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self._state_bv = BV(bits_for(nstates-1))
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self._state = Signal(self._state_bv)
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self._next_state = Signal(self._state_bv)
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for n, state in enumerate(states):
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setattr(self, state, Constant(n, self._state_bv))
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self.actions = [[] for i in range(len(states))]
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for name, target, delay in delayed_enters:
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target_state = getattr(self, target)
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if delay:
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name_state = len(self.actions)
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setattr(self, name, Constant(name_state, self._state_bv))
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for i in range(delay-1):
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self.actions.append([self.next_state(Constant(name_state+i+1, self._state_bv))])
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self.actions.append([self.next_state(target_state)])
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else:
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# alias
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setattr(self, name, getattr(self, target_state))
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def reset_state(self, state):
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self._state.reset = state
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def next_state(self, state):
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return self._next_state.eq(state)
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def act(self, state, *statements):
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self.actions[state.n] += statements
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def get_fragment(self):
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cases = [[Constant(s, self._state_bv)] + a
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for s, a in enumerate(self.actions) if a]
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comb = [
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self._next_state.eq(self._state),
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Case(self._state, *cases)
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]
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sync = [self._state.eq(self._next_state)]
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return Fragment(comb, sync)
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