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

#include <dsp.h>

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

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

Public Member Functions
	fir_resampler (scheduler *sch, int _ncoeffs, Tc *_coeffs, pipebuf< T > &_in, pipebuf< T > &_out, int _interp=1, int _decim=1)
void	run ()
Public Member Functions inherited from leansdr::runnable
	runnable (scheduler *_sch, const char *name)
Public Member Functions inherited from leansdr::runnable_common
	runnable_common (const char *_name)
virtual	~runnable_common ()
virtual void	shutdown ()

Public Attributes
float *	freq_tap
float	tap_multiplier
float	freq_tol
Public Attributes inherited from leansdr::runnable_common
const char *	name

Private Member Functions
void	set_freq (float f)

Private Attributes
unsigned int	ncoeffs
Tc *	coeffs
int	interp
int	decim
pipereader< T >	in
pipewriter< T >	out
T *	shifted_coeffs
float	current_freq

Additional Inherited Members
Protected Attributes inherited from leansdr::runnable
scheduler *	sch

Detailed Description

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

Definition at line 348 of file dsp.h.

Constructor & Destructor Documentation

fir_resampler()

template<typename T , typename Tc >

leansdr::fir_resampler< T, Tc >::fir_resampler ( scheduler *  sch, int  _ncoeffs, Tc *  _coeffs, pipebuf< T > &  _in, pipebuf< T > &  _out, int  _interp = 1, int  _decim = 1  )

inline

Definition at line 350 of file dsp.h.

References leansdr::fail().

        : runnable(sch, "fir_resampler"),
          ncoeffs(_ncoeffs), coeffs(_coeffs),
          interp(_interp), decim(_decim),
          in(_in), out(_out, interp),
          freq_tap(NULL), tap_multiplier(1), freq_tol(0.1)
    {
        if (decim != 1)
            fail("fir_resampler: decim not implemented"); // TBD
        shifted_coeffs = new T[ncoeffs];
        set_freq(0);
    }

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Member Function Documentation

run()

template<typename T , typename Tc >

void leansdr::fir_resampler< T, Tc >::run ( )

inlinevirtual

Reimplemented from leansdr::runnable_common.

Definition at line 365 of file dsp.h.

References i, leansdr::cconverter< Tin, Zin, Tout, Zout, Gn, Gd >::in, leansdr::min(), leansdr::cconverter< Tin, Zin, Tout, Zout, Gn, Gd >::out, leansdr::runnable::sch, and leansdr::scheduler::verbose.

    {
        if (in.readable() < ncoeffs)
            return;

        if (freq_tap)
        {
            float new_freq = *freq_tap * tap_multiplier;
            if (fabs(current_freq - new_freq) > freq_tol)
            {
                if (sch->verbose)
                    fprintf(stderr, "Shifting filter %f -> %f\n",
                            current_freq, new_freq);
                set_freq(new_freq);
            }
        }

        if (in.readable() * interp < ncoeffs)
            return;
        unsigned long count = min((in.readable() * interp - ncoeffs) / interp,
                                  out.writable() / interp);
        int latency = (ncoeffs + interp) / interp;
        T *pin = in.rd() + latency, *pend = pin + count, *pout = out.wr();
        // TBD use coeffs when current_freq=0 (fewer mults if float)
        for (; pin < pend; ++pin)
        {
            for (int i = 0; i < interp; ++i, ++pout)
            {
                T *pi = pin;
                T *pc = shifted_coeffs + i, *pcend = shifted_coeffs + ncoeffs;
                T x = 0;
                for (; pc < pcend; pc += interp, --pi)
                    x = x + (*pc) * (*pi);
                *pout = x;
            }
        }
        in.read(count);
        out.written(count * interp);
    }

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set_freq()

template<typename T , typename Tc >

void leansdr::fir_resampler< T, Tc >::set_freq ( float  f )

inlineprivate

Definition at line 420 of file dsp.h.

References i, and M_PI.

    {
        for (int i = 0; i < ncoeffs; ++i)
        {
            float a = 2 * M_PI * f * i;
            float c = cosf(a), s = sinf(a);
            // TBD Support T=complex
            shifted_coeffs[i].re = coeffs[i] * c;
            shifted_coeffs[i].im = coeffs[i] * s;
        }
        current_freq = f;
    }

Member Data Documentation

coeffs

template<typename T , typename Tc >

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

private

Definition at line 407 of file dsp.h.

current_freq

template<typename T , typename Tc >

float leansdr::fir_resampler< T, Tc >::current_freq

private

Definition at line 419 of file dsp.h.

decim

template<typename T , typename Tc >

int leansdr::fir_resampler< T, Tc >::decim

private

Definition at line 408 of file dsp.h.

freq_tap

template<typename T , typename Tc >

float* leansdr::fir_resampler< T, Tc >::freq_tap

Definition at line 413 of file dsp.h.

freq_tol

template<typename T , typename Tc >

float leansdr::fir_resampler< T, Tc >::freq_tol

Definition at line 415 of file dsp.h.

in

template<typename T , typename Tc >

pipereader<T> leansdr::fir_resampler< T, Tc >::in

private

Definition at line 409 of file dsp.h.

interp

template<typename T , typename Tc >

int leansdr::fir_resampler< T, Tc >::interp

private

Definition at line 408 of file dsp.h.

ncoeffs

template<typename T , typename Tc >

unsigned int leansdr::fir_resampler< T, Tc >::ncoeffs

private

Definition at line 406 of file dsp.h.

out

template<typename T , typename Tc >

pipewriter<T> leansdr::fir_resampler< T, Tc >::out

private

Definition at line 410 of file dsp.h.

shifted_coeffs

template<typename T , typename Tc >

T* leansdr::fir_resampler< T, Tc >::shifted_coeffs

private

Definition at line 418 of file dsp.h.

tap_multiplier

template<typename T , typename Tc >

float leansdr::fir_resampler< T, Tc >::tap_multiplier

Definition at line 414 of file dsp.h.

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

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