93 lines
2.9 KiB
Python
93 lines
2.9 KiB
Python
# 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.regression import TestFactory
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from cocotb.result import SimTimeoutError
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from cocotb.triggers import ClockCycles, FallingEdge, RisingEdge, Timer, with_timeout
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from .util import compare_lists, send_recovered_bits, timeout, with_valids
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def scramble(bits):
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lfsr = random.randrange(1, 0x7ff)
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for bit in bits:
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ldd = (lfsr >> 10) ^ ((lfsr >> 8) & 1)
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yield bit ^ ldd
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lfsr <<= 1
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lfsr &= 0x7ff
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lfsr |= ldd
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async def send_scrambled(descrambler, data, valids):
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descrambler.signal_status.value = 1
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await send_recovered_bits(descrambler.clk, descrambler.scrambled,
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descrambler.scrambled_valid, scramble(data), valids)
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descrambler.signal_status.value = 0
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@timeout(10, 'us')
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async def test_unlock(descrambler, valids):
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descrambler.signal_status.value = 0
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descrambler.scrambled_valid.value = 0
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descrambler.test_mode.value = 1
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await Timer(1)
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await cocotb.start(Clock(descrambler.clk, 8, units='ns').start())
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await cocotb.start(send_scrambled(descrambler,
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itertools.chain(itertools.repeat(1, 60),
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itertools.repeat(0, 625//2),
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itertools.repeat(1, 29),
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itertools.repeat(0)),
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valids))
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await ClockCycles(descrambler.clk, 60)
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assert descrambler.locked.value
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try:
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await with_timeout(FallingEdge(descrambler.locked), 6, 'us')
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except SimTimeoutError:
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pass
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else:
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assert False
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await FallingEdge(descrambler.locked)
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with_valids(globals(), test_unlock)
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@timeout(10, 'us')
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async def test_descramble(descrambler, valids):
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descrambler.signal_status.value = 0
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descrambler.scrambled_valid.value = 0
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descrambler.test_mode.value = 0
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await Timer(1)
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await cocotb.start(Clock(descrambler.clk, 8, units='ns').start())
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ins = [1] * 60 + [0] + [random.randrange(2) for _ in range(1000)]
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await cocotb.start(send_scrambled(descrambler, ins, valids))
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outs = []
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await RisingEdge(descrambler.locked)
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while descrambler.locked.value:
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await RisingEdge(descrambler.clk)
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valid = descrambler.unscrambled_valid.value
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if valid == 0:
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pass
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elif valid == 1:
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outs.append(descrambler.unscrambled[1].value)
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else:
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outs.append(descrambler.unscrambled[1].value)
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outs.append(descrambler.unscrambled[0].value)
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best_corr = -1
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best_off = None
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for off in range(28, 42):
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corr = sum(i == o for i, o in zip(ins[off:], outs))
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if corr > best_corr:
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best_corr = corr
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best_off = off
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print(f"best offset is {best_off} correlation {best_corr/(len(ins) - best_off)}")
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compare_lists(ins[best_off:], outs)
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with_valids(globals(), test_descramble)
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