67 lines
2.3 KiB
Python
67 lines
2.3 KiB
Python
"""
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Copyright (c) 2020 Alex Forencich
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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"""
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import cocotb
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from cocotb.triggers import RisingEdge, FallingEdge
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class Reset:
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def _init_reset(self, reset_signal=None, active_level=True):
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self._local_reset = False
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self._ext_reset = False
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self._reset_state = True
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if reset_signal is not None:
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cocotb.start_soon(self._run_reset(reset_signal, bool(active_level)))
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self._update_reset()
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def assert_reset(self, val=None):
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if val is None:
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self.assert_reset(True)
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self.assert_reset(False)
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else:
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self._local_reset = bool(val)
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self._update_reset()
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def _update_reset(self):
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new_state = self._local_reset or self._ext_reset
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if self._reset_state != new_state:
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self._reset_state = new_state
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self._handle_reset(new_state)
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def _handle_reset(self, state):
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pass
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async def _run_reset(self, reset_signal, active_level):
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while True:
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if bool(reset_signal.value):
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await FallingEdge(reset_signal)
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self._ext_reset = not active_level
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self._update_reset()
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else:
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await RisingEdge(reset_signal)
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self._ext_reset = active_level
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self._update_reset()
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