RTLSDRRX.hxx

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#pragma once
/*
Copyright (c) 2026 Matthew H. Reilly (kb1vc)
All rights reserved.
 
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
 
    Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.
    Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions and the following disclaimer in
    the documentation and/or other materials provided with the
    distribution.
 
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

 
#include "RadioRX.hxx"
#include "Params.hxx"
#include "QuadratureOscillator.hxx"
#include "RTLSDRDev.hxx"
#include <SoDa/ReSampler.hxx>
#include <vector>
#include <complex>
#include <memory>
#include <mutex>
#include <thread>
#include <atomic>
 
namespace SoDa {
 
  class RTLSDRRX;
  using RTLSDRRXPtr = std::shared_ptr<RTLSDRRX>;
 
  class RTLSDRRX : public RadioRX {
  protected:
    RTLSDRRX(RTLSDRDevPtr dev_in, ParamsPtr params);
 
  public:
    ~RTLSDRRX() = default;
 
    static RTLSDRRXPtr make(RTLSDRDevPtr dev_in, ParamsPtr params) {
      auto ret = std::shared_ptr<RTLSDRRX>(new RTLSDRRX(dev_in, params));
      ret->self = ret;
      ret->registerThread(ret);
      return ret;
    }
 
    void init() override;
 
    void setNCOFreq(double freq) override;
    bool downConvert() override;
 
    void startStream()   override;
    void stopStream()    override;
    bool streamEnabled() override { return streaming; }
    void enableIFStreamer(bool enable) override { if_streaming_enabled = enable; }
 
  private:
    void doMixer(std::vector<std::complex<float>> & buf);
    static void asyncCallback(unsigned char* buf, uint32_t len, void* ctx);
 
    RTLSDRDevPtr rtl;
 
    static constexpr float        HW_RATE    = 2048000.0f;  // RTL2832U actual USB delivery rate
    static constexpr unsigned int READ_BYTES = 16384;  // always divisible by 512
    static constexpr unsigned int RAW_ACCU_MAX = 8;    // max resampler blocks to buffer (~400ms)
 
    unsigned int rs_in_size;   
    unsigned int rs_out_size;  
    unsigned int rf_buf_size;  
 
    double rx_sample_rate;     
 
    std::atomic<bool> streaming{false};
    bool if_streaming_enabled;
 
    std::atomic<unsigned int> diag_reads{0};  
    unsigned int diag_resamp_runs;            
    unsigned int diag_published;              
 
    SoDa::ReSamplerPtr hw_resampler;  
 
    std::mutex                          raw_accu_mutex;
    std::vector<std::complex<float>>    raw_accu;  
    std::vector<std::complex<float>>    rs_in;     
    std::vector<std::complex<float>>    rs_out;    
    std::vector<std::complex<float>>    accu;      
 
    std::thread async_rx_thread;
 
    QuadratureOscillator IF_osc;
 
    std::weak_ptr<RTLSDRRX> self;
  };
 
} // namespace SoDa