leansdr::fir_sampler< T, Tc > Struct Template Reference

#include <sdr.h>

Inheritance diagram for leansdr::fir_sampler< T, Tc >:

Collaboration diagram for leansdr::fir_sampler< T, Tc >:

Public Member Functions
	fir_sampler (int _ncoeffs, Tc *_coeffs, int _subsampling=1)
int	readahead ()
complex< T >	interp (const complex< T > *pin, float mu, float phase)
void	update_freq (float freqw, int period)
Public Member Functions inherited from leansdr::sampler_interface< T >
virtual	~sampler_interface ()

Private Member Functions
void	do_update_freq (float freqw)

Private Attributes
trig16	trig
int	ncoeffs
Tc *	coeffs
int	subsampling
cf32 *	shifted_coeffs
int	update_freq_phase

Detailed Description

template<typename T, typename Tc>
struct leansdr::fir_sampler< T, Tc >

Definition at line 958 of file sdr.h.

Constructor & Destructor Documentation

fir_sampler()

template<typename T, typename Tc>

leansdr::fir_sampler< T, Tc >::fir_sampler ( int  _ncoeffs, Tc *  _coeffs, int  _subsampling = 1  )

inline

Definition at line 960 of file sdr.h.

                                                                 : ncoeffs(_ncoeffs),
                                                                   coeffs(_coeffs),
                                                                   subsampling(_subsampling),
                                                                   shifted_coeffs(new complex<T>[ncoeffs]),
                                                                   update_freq_phase(0)
    {
        do_update_freq(0); // In case application never calls update_freq()
    }

Member Function Documentation

do_update_freq()

template<typename T, typename Tc>

void leansdr::fir_sampler< T, Tc >::do_update_freq ( float  freqw )

inlineprivate

Definition at line 1015 of file sdr.h.

References leansdr::auto_notch< T >::slot::i.

    {
        float f = freqw / subsampling;
        for (int i = 0; i < ncoeffs; ++i)
            shifted_coeffs[i] = trig.expi(-f * (i - ncoeffs / 2)) * coeffs[i];
    }

interp()

template<typename T, typename Tc>

complex<T> leansdr::fir_sampler< T, Tc >::interp ( const complex< T > *  pin, float  mu, float  phase  )

inlinevirtual

Implements leansdr::sampler_interface< T >.

Definition at line 974 of file sdr.h.

    {
        // Apply FIR filter with subsampling
        complex<T> acc(0, 0);
        complex<T> *pc = shifted_coeffs + (int)((1 - mu) * subsampling);
        complex<T> *pcend = shifted_coeffs + ncoeffs;

        if (subsampling == 1)
        {
            // Special case for heavily oversampled signals,
            // where filtering is expensive.
            // gcc-4.9.2 can vectorize this form with NEON on ARM.
            while (pc < pcend)
                acc += (*pc++) * (*pin++);
        }
        else
        {
            // Not vectorized because the coefficients are not
            // guaranteed to be contiguous in memory.
            for (; pc < pcend; pc += subsampling, ++pin)
                acc += (*pc) * (*pin);
        }

        // Derotate
        return trig.expi(-phase) * acc;
    }

readahead()

template<typename T, typename Tc>

int leansdr::fir_sampler< T, Tc >::readahead ( )

inlinevirtual

Implements leansdr::sampler_interface< T >.

Definition at line 969 of file sdr.h.

    {
        return ncoeffs - 1;
    }

update_freq()

template<typename T, typename Tc>

void leansdr::fir_sampler< T, Tc >::update_freq ( float  freqw, int  period  )

inlinevirtual

Reimplemented from leansdr::sampler_interface< T >.

Definition at line 1001 of file sdr.h.

    {
        // Throttling: Update one coeff per 16 processed samples,
        // to keep the overhead of freq tracking below about 10%.
        update_freq_phase -= period;

        if (update_freq_phase <= 0)
        {
            update_freq_phase = ncoeffs * 16;
            do_update_freq(freqw);
        }
    }

Member Data Documentation

coeffs

template<typename T, typename Tc>

Tc* leansdr::fir_sampler< T, Tc >::coeffs

private

Definition at line 1024 of file sdr.h.

ncoeffs

template<typename T, typename Tc>

int leansdr::fir_sampler< T, Tc >::ncoeffs

private

Definition at line 1023 of file sdr.h.

shifted_coeffs

template<typename T, typename Tc>

cf32* leansdr::fir_sampler< T, Tc >::shifted_coeffs

private

Definition at line 1026 of file sdr.h.

subsampling

template<typename T, typename Tc>

int leansdr::fir_sampler< T, Tc >::subsampling

private

Definition at line 1025 of file sdr.h.

trig

template<typename T, typename Tc>

trig16 leansdr::fir_sampler< T, Tc >::trig

private

Definition at line 1022 of file sdr.h.

update_freq_phase

template<typename T, typename Tc>

int leansdr::fir_sampler< T, Tc >::update_freq_phase

private

Definition at line 1027 of file sdr.h.

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The documentation for this struct was generated from the following file:

• plugins/channelrx/demoddatv/leansdr/sdr.h