class compress : public gr::sync_block

{



public:

#if GNURADIO_VERSION < 0x030900

typedef boost::shared_ptr<compress> sptr;

#else

typedef std::shared_ptr<compress> sptr;

#endif

	static compress::sptr make(float threshold, float gain)

	{

		return gnuradio::get_initial_sptr(new compress(threshold, gain));

	}

	compress(float threshold, float gain);

	virtual ~compress();

	int work(int noutput_items,

			gr_vector_const_void_star &input_items,

			gr_vector_void_star &output_items) override;



private:

	float d_threshold;

	float d_gain;

};



compress::compress(float threshold, float gain): gr::sync_block ("compress",

						gr::io_signature::make (1, 1, sizeof(float)),

						gr::io_signature::make (1, 1, sizeof(float))),

						d_threshold(threshold),

						d_gain(gain)

{

}



compress::~compress()

{

}



int compress::work(int noutput_items,

		gr_vector_const_void_star &input_items,

		gr_vector_void_star &output_items)

{

	const float *in = (const float *) input_items[0];

	float *out = (float *) output_items[0];

	for(int k=0;k<noutput_items;k++)

	{

		float m=std::max(std::abs(in[k]),1e-20f);

		float lm=std::log10(m)*10.f;

		float g=d_gain;

		if(lm>d_threshold)

		{

			g=g/d_threshold*lm;

		}

		float ga=pow(10.f,g*0.1f);

		out[k]=in[k]*ga;

	}

	return noutput_items;

}