55 lines
1.4 KiB
Python
55 lines
1.4 KiB
Python
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# SPDX-License-Identifier: AGPL-3.0-Only
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# Copyright (C) 2022 Sean Anderson <seanga2@gmail.com>
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import itertools
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import random
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import cocotb
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from cocotb.clock import Clock
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from cocotb.triggers import FallingEdge, RisingEdge, Timer
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from .util import alist, ReverseList, print_list_at, compare_lists
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threshold = 32
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def descramble(scrambled):
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locked = False
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lfsr = ReverseList([0] * 11)
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for s in scrambled:
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ldd = lfsr[8] ^ lfsr[10]
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if s ^ ldd:
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consecutive += 1
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else:
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consecutive = 0
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if consecutive >= threshold:
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locked = True
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if locked:
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yield s ^ ldd
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lfsr.append(ldd)
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else:
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lfsr.append(0 if s else 1)
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@cocotb.test(timeout_time=10, timeout_unit='us')
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async def test_scramble(scrambler):
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scrambler.unscrambled.value = 1
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await Timer(1)
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await cocotb.start(Clock(scrambler.clk, 8, units='ns').start())
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idles = threshold + 10
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ins = [1] * idles + [0] + [random.randrange(2) for _ in range(1000)]
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async def send():
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for bit in ins:
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await FallingEdge(scrambler.clk)
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scrambler.unscrambled.value = bit
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await cocotb.start(send())
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outs = []
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for _ in ins:
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await RisingEdge(scrambler.clk)
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outs.append(scrambler.scrambled.value)
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compare_lists(ins[idles-1:], list(descramble(outs)))
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