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37 lines
714 B
C++
37 lines
714 B
C++
// Copyright 2020 modemm17 LLC.
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#pragma once
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#include <bit>
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#include <cstdint>
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#include "Util.h"
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namespace modemm17
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{
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struct M17Synchronizer
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{
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uint16_t expected_;
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int allowable_errors_;
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uint16_t buffer_ = 0;
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M17Synchronizer(uint16_t word = 0x3243, int bit_errors = 1)
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: expected_(word), allowable_errors_(bit_errors)
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{}
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bool operator()(int bits)
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{
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// Add one symbol (2 bits) of data to the synchronizer.
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// Returns true when a sync word has been detected.
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buffer_ = ((buffer_ << 2) | bits) & 0xFFFF;
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auto tmp = buffer_ ^ expected_;
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return popcount(tmp) <= allowable_errors_;
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}
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void reset() { buffer_ = 0; }
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};
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} // modemm17
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