resampling.h

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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef SP_RESAMPLING_H
#define SP_RESAMPLING_H
 
namespace sp
{
 
template <class T1> arma::Col<T1> upsample( const arma::Col<T1>& x, const int p )
{
    long int      N = x.size();
    arma::Col<T1> y;
    y.set_size( p * N );
    y.zeros();
    for( long int n = 0; n < N; n++ )
        y[p * n] = x[n];
    return y;
}
 
template <class T1> arma::Col<T1> downsample( const arma::Col<T1>& x, const int q )
{
    arma::Col<T1> y;
    int           N = int( floor( 1.0 * x.size() / q ) );
    y.set_size( N );
    for( long int n = 0; n < N; n++ )
        y[n] = x[n * q];
    return y;
}
 
template <class T1> class resampling
{
  private:
    FIR_filt<T1, double, T1> aa_filt;
    arma::vec                H; 
    arma::vec                K; 
    arma::uword              P; 
    arma::uword              Q; 
 
  public:
    resampling( const arma::uword _P, const arma::uword _Q, const arma::vec _H )
    {
        P = _P;
        Q = _Q;
        H = _H;
        K = H.n_elem;
        aa_filt.set_coeffs( H );
    }
 
    resampling( const arma::uword _P, const arma::uword _Q )
    {
        P             = _P;
        Q             = _Q;
        arma::uword M = ( P > Q ) ? P : Q;
        H             = fir1( 8 * M, 1.0f / M );
        K             = H.n_elem;
        aa_filt.set_coeffs( H );
    }
 
    ~resampling()
    {
    }
 
    void downfir( const arma::Col<T1>& in, arma::Col<T1>& out )
    {
        arma::uword sz = in.n_elem;
        for( arma::uword n = 0; n < sz; n++ )
        {
            T1 tmp = aa_filt( in[n] );
            if( n % Q == 0 )
                out[n / Q] = tmp;
        }
    }
 
    void upfir( const arma::Col<T1>& in, arma::Col<T1>& out )
    {
        arma::uword sz = P * in.n_elem;
        for( arma::uword n = 0; n < sz; n++ )
        {
            if( n % P == 0 )
                out[n] = P * aa_filt( in[n / P] );
            else
                out[n] = P * aa_filt( 0.0 );
        }
    }
 
    void upfirdown( const arma::Col<T1>& in, arma::Col<T1>& out )
    {
        arma::uword sz = P * in.n_elem;
        T1          tmp;
        for( arma::uword n = 0; n < sz; n++ )
        {
            if( n % P == 0 )
                tmp = aa_filt( in[n / P] );
            else
                tmp = aa_filt( 0.0 );
            if( n % Q == 0 )
                out[n / Q] = P * tmp;
        }
    }
};
 
} // namespace sp
#endif