kopia lustrzana https://github.com/mobilinkd/tnc3-firmware
47 wiersze
1.2 KiB
C++
47 wiersze
1.2 KiB
C++
// Copyright 2017-2020 Rob Riggs <rob@mobilinkd.com>
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// All rights reserved.
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#include "AfskDemodulator.hpp"
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namespace mobilinkd { namespace tnc { namespace afsk1200 {
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hdlc::IoFrame* Demodulator::operator()(q15_t* samples, size_t len)
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{
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hdlc::IoFrame* result = 0;
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float* fa = audio_filter_(samples);
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for (size_t i = 0; i != len; i++) {
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buffer_[i] = int16_t(fa[i]);
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}
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for (size_t i = 0; i != len; i++) {
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bool level = (buffer_[i] >= 0);
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bool delayed = delay_line_(level);
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buffer_[i] = (int16_t(level ^ delayed) << 1) - 1;
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}
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auto* fc = lpf_filter_.filter(buffer_);
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for (size_t i = 0; i != len; i++) {
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bool bit = fc[i] >= 0;
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auto pll = pll_(bit);
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if (pll.sample) {
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locked_ = pll.locked;
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// We will only ever get one frame because there are
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// not enough bits in a block for more than one.
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if (result) {
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auto tmp = hdlc_decoder_(nrzi_.decode(bit), true);
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if (tmp) hdlc::release(tmp);
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} else {
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result = hdlc_decoder_(nrzi_.decode(bit), true);
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}
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}
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}
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return result;
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}
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}}} // mobilinkd::tnc::afsk1200
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