X-Git-Url: https://git.gag.com/?a=blobdiff_plain;ds=sidebyside;f=gnuradio-core%2Fsrc%2Flib%2Ffilter%2Fgri_fft_filter_ccc_generic.cc;fp=gnuradio-core%2Fsrc%2Flib%2Ffilter%2Fgri_fft_filter_ccc_generic.cc;h=1bf4a6f4bffa894f0930ed23f98518e3e02f4de0;hb=fd9980f919b6f05e2fbea404fea322825ce438f0;hp=0000000000000000000000000000000000000000;hpb=2415ccdbf9d97878a0888bbdff30d699ae2326dd;p=debian%2Fgnuradio diff --git a/gnuradio-core/src/lib/filter/gri_fft_filter_ccc_generic.cc b/gnuradio-core/src/lib/filter/gri_fft_filter_ccc_generic.cc new file mode 100644 index 00000000..1bf4a6f4 --- /dev/null +++ b/gnuradio-core/src/lib/filter/gri_fft_filter_ccc_generic.cc @@ -0,0 +1,167 @@ +/* -*- c++ -*- */ +/* + * Copyright 2010 Free Software Foundation, Inc. + * + * This file is part of GNU Radio + * + * GNU Radio is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 3, or (at your option) + * any later version. + * + * GNU Radio is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GNU Radio; see the file COPYING. If not, write to + * the Free Software Foundation, Inc., 51 Franklin Street, + * Boston, MA 02110-1301, USA. + */ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include +#include +#include +#include +#include +#include +#include + +gri_fft_filter_ccc_generic::gri_fft_filter_ccc_generic (int decimation, + const std::vector &taps) + : d_fftsize(-1), d_decimation(decimation), d_fwdfft(0), d_invfft(0) +{ + set_taps(taps); +} + +gri_fft_filter_ccc_generic::~gri_fft_filter_ccc_generic () +{ + delete d_fwdfft; + delete d_invfft; +} + +#if 0 +static void +print_vector_complex(const std::string label, const std::vector &x) +{ + std::cout << label; + for (unsigned i = 0; i < x.size(); i++) + std::cout << x[i] << " "; + std::cout << "\n"; +} +#endif + + +/* + * determines d_ntaps, d_nsamples, d_fftsize, d_xformed_taps + */ +int +gri_fft_filter_ccc_generic::set_taps (const std::vector &taps) +{ + int i = 0; + compute_sizes(taps.size()); + + d_tail.resize(tailsize()); + for (i = 0; i < tailsize(); i++) + d_tail[i] = 0; + + gr_complex *in = d_fwdfft->get_inbuf(); + gr_complex *out = d_fwdfft->get_outbuf(); + + float scale = 1.0 / d_fftsize; + + // Compute forward xform of taps. + // Copy taps into first ntaps slots, then pad with zeros + for (i = 0; i < d_ntaps; i++) + in[i] = taps[i] * scale; + + for (; i < d_fftsize; i++) + in[i] = 0; + + d_fwdfft->execute(); // do the xform + + // now copy output to d_xformed_taps + for (i = 0; i < d_fftsize; i++) + d_xformed_taps[i] = out[i]; + + return d_nsamples; +} + +// determine and set d_ntaps, d_nsamples, d_fftsize + +void +gri_fft_filter_ccc_generic::compute_sizes(int ntaps) +{ + int old_fftsize = d_fftsize; + d_ntaps = ntaps; + d_fftsize = (int) (2 * pow(2.0, ceil(log(ntaps) / log(2)))); + d_nsamples = d_fftsize - d_ntaps + 1; + + if (0) + fprintf(stderr, "gri_fft_filter_ccc_generic: ntaps = %d, fftsize = %d, nsamples = %d\n", + d_ntaps, d_fftsize, d_nsamples); + + assert(d_fftsize == d_ntaps + d_nsamples -1 ); + + if (d_fftsize != old_fftsize){ // compute new plans + delete d_fwdfft; + delete d_invfft; + d_fwdfft = new gri_fft_complex(d_fftsize, true); + d_invfft = new gri_fft_complex(d_fftsize, false); + d_xformed_taps.resize(d_fftsize); + } +} + +int +gri_fft_filter_ccc_generic::filter (int nitems, const gr_complex *input, gr_complex *output) +{ + int dec_ctr = 0; + int j = 0; + int ninput_items = nitems * d_decimation; + + for (int i = 0; i < ninput_items; i += d_nsamples){ + + memcpy(d_fwdfft->get_inbuf(), &input[i], d_nsamples * sizeof(gr_complex)); + + for (j = d_nsamples; j < d_fftsize; j++) + d_fwdfft->get_inbuf()[j] = 0; + + d_fwdfft->execute(); // compute fwd xform + + gr_complex *a = d_fwdfft->get_outbuf(); + gr_complex *b = &d_xformed_taps[0]; + gr_complex *c = d_invfft->get_inbuf(); + + for (j = 0; j < d_fftsize; j+=1) { // filter in the freq domain + c[j] = a[j] * b[j]; + } + + d_invfft->execute(); // compute inv xform + + // add in the overlapping tail + + for (j = 0; j < tailsize(); j++) + d_invfft->get_outbuf()[j] += d_tail[j]; + + // copy nsamples to output + j = dec_ctr; + while (j < d_nsamples) { + *output++ = d_invfft->get_outbuf()[j]; + j += d_decimation; + } + dec_ctr = (j - d_nsamples); + + // stash the tail + memcpy(&d_tail[0], d_invfft->get_outbuf() + d_nsamples, + tailsize() * sizeof(gr_complex)); + } + + assert(dec_ctr == 0); + + return nitems; +}