3 * Copyright 2009 Free Software Foundation, Inc.
5 * This file is part of GNU Radio
7 * GNU Radio is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 3, or (at your option)
12 * GNU Radio is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with GNU Radio; see the file COPYING. If not, write to
19 * the Free Software Foundation, Inc., 51 Franklin Street,
20 * Boston, MA 02110-1301, USA.
27 #include <gr_pfb_arb_resampler_ccf.h>
28 #include <gr_fir_ccf.h>
29 #include <gr_fir_util.h>
30 #include <gr_io_signature.h>
33 gr_pfb_arb_resampler_ccf_sptr gr_make_pfb_arb_resampler_ccf (float rate,
34 const std::vector<float> &taps,
35 unsigned int filter_size)
37 return gr_pfb_arb_resampler_ccf_sptr (new gr_pfb_arb_resampler_ccf (rate, taps,
42 gr_pfb_arb_resampler_ccf::gr_pfb_arb_resampler_ccf (float rate,
43 const std::vector<float> &taps,
44 unsigned int filter_size)
45 : gr_block ("pfb_arb_resampler_ccf",
46 gr_make_io_signature (1, 1, sizeof(gr_complex)),
47 gr_make_io_signature (1, 1, sizeof(gr_complex))),
50 /* The number of filters is specified by the user as the filter size;
51 this is also the interpolation rate of the filter. We use it and the
52 rate provided to determine the decimation rate. This acts as a
53 rational resampler. The flt_rate is calculated as the residual
54 between the integer decimation rate and the real decimation rate and
55 will be used to determine to interpolation point of the resampling
58 d_int_rate = filter_size;
59 d_dec_rate = (unsigned int)floor(d_int_rate/rate);
60 d_flt_rate = (d_int_rate/rate) - d_dec_rate;
62 // Store the last filter between calls to work
67 d_filters = std::vector<gr_fir_ccf*>(d_int_rate);
68 d_diff_filters = std::vector<gr_fir_ccf*>(d_int_rate);
70 // Create an FIR filter for each channel and zero out the taps
71 std::vector<float> vtaps(0, d_int_rate);
72 for(int i = 0; i < d_int_rate; i++) {
73 d_filters[i] = gr_fir_util::create_gr_fir_ccf(vtaps);
74 d_diff_filters[i] = gr_fir_util::create_gr_fir_ccf(vtaps);
77 // Now, actually set the filters' taps
78 std::vector<float> dtaps;
79 create_diff_taps(taps, dtaps);
80 set_taps(taps, d_taps, d_filters);
81 set_taps(dtaps, d_dtaps, d_diff_filters);
84 gr_pfb_arb_resampler_ccf::~gr_pfb_arb_resampler_ccf ()
86 for(unsigned int i = 0; i < d_int_rate; i++) {
92 gr_pfb_arb_resampler_ccf::set_taps (const std::vector<float> &newtaps,
93 std::vector< std::vector<float> > &ourtaps,
94 std::vector<gr_fir_ccf*> &ourfilter)
98 unsigned int ntaps = newtaps.size();
99 d_taps_per_filter = (unsigned int)ceil((double)ntaps/(double)d_int_rate);
101 // Create d_numchan vectors to store each channel's taps
102 ourtaps.resize(d_int_rate);
104 // Make a vector of the taps plus fill it out with 0's to fill
105 // each polyphase filter with exactly d_taps_per_filter
106 std::vector<float> tmp_taps;
108 while((float)(tmp_taps.size()) < d_int_rate*d_taps_per_filter) {
109 tmp_taps.push_back(0.0);
112 // Partition the filter
113 for(i = 0; i < d_int_rate; i++) {
114 // Each channel uses all d_taps_per_filter with 0's if not enough taps to fill out
115 ourtaps[d_int_rate-1-i] = std::vector<float>(d_taps_per_filter, 0);
116 for(j = 0; j < d_taps_per_filter; j++) {
117 ourtaps[d_int_rate - 1 - i][j] = tmp_taps[i + j*d_int_rate];
120 // Build a filter for each channel and add it's taps to it
121 ourfilter[i]->set_taps(ourtaps[d_int_rate-1-i]);
124 // Set the history to ensure enough input items for each filter
125 set_history (d_taps_per_filter + 1);
131 gr_pfb_arb_resampler_ccf::create_diff_taps(const std::vector<float> &newtaps,
132 std::vector<float> &difftaps)
134 float maxtap = 1e-20;
136 difftaps.push_back(0); //newtaps[0]);
137 for(unsigned int i = 1; i < newtaps.size()-1; i++) {
138 float tap = newtaps[i+1] - newtaps[i-1];
139 difftaps.push_back(tap);
144 difftaps.push_back(0);//-newtaps[newtaps.size()-1]);
146 // Scale the differential taps; helps scale error term to better update state
147 // FIXME: should this be scaled this way or use the same gain as the taps?
148 for(unsigned int i = 0; i < difftaps.size(); i++) {
149 difftaps[i] /= maxtap;
154 gr_pfb_arb_resampler_ccf::print_taps()
157 for(i = 0; i < d_int_rate; i++) {
158 printf("filter[%d]: [", i);
159 for(j = 0; j < d_taps_per_filter; j++) {
160 printf(" %.4e", d_taps[i][j]);
167 gr_pfb_arb_resampler_ccf::general_work (int noutput_items,
168 gr_vector_int &ninput_items,
169 gr_vector_const_void_star &input_items,
170 gr_vector_void_star &output_items)
172 gr_complex *in = (gr_complex *) input_items[0];
173 gr_complex *out = (gr_complex *) output_items[0];
177 return 0; // history requirements may have changed.
180 int i = 0, j, count = d_start_index;
183 // Restore the last filter position
186 // produce output as long as we can and there are enough input samples
187 while((i < noutput_items) && (count < ninput_items[0]-1)) {
189 // start j by wrapping around mod the number of channels
190 while((j < d_int_rate) && (i < noutput_items)) {
191 // Take the current filter output
192 o0 = d_filters[j]->filter(&in[count]);
193 o1 = d_diff_filters[j]->filter(&in[count]);
195 out[i] = o0 + o1*d_flt_rate; // linearly interpolate between samples
200 if(i < noutput_items) { // keep state for next entry
201 float ss = (int)(j / d_int_rate); // number of items to skip ahead by
202 count += ss; // we have fully consumed another input
203 j = j % d_int_rate; // roll filter around
207 // Store the current filter position and start of next sample
209 d_start_index = std::max(0, count - ninput_items[0]);
211 // consume all we've processed but no more than we can
212 consume_each(std::min(count, ninput_items[0]));