--- /dev/null
+/* -*- c++ -*- */
+/*
+ * Copyright 2004,2007 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 <gr_io_signature.h>
+#include <gr_fractional_interpolator_ff.h>
+#include <gri_mmse_fir_interpolator.h>
+#include <stdexcept>
+
+// Public constructor
+gr_fractional_interpolator_ff_sptr gr_make_fractional_interpolator_ff(float phase_shift, float interp_ratio)
+{
+ return gr_fractional_interpolator_ff_sptr(new gr_fractional_interpolator_ff(phase_shift, interp_ratio));
+}
+
+gr_fractional_interpolator_ff::gr_fractional_interpolator_ff(float phase_shift, float interp_ratio)
+ : gr_block ("fractional_interpolator_ff",
+ gr_make_io_signature (1, 1, sizeof (float)),
+ gr_make_io_signature (1, 1, sizeof (float))),
+ d_mu (phase_shift), d_mu_inc (interp_ratio), d_interp(new gri_mmse_fir_interpolator())
+{
+ if (interp_ratio <= 0)
+ throw std::out_of_range ("interpolation ratio must be > 0");
+ if (phase_shift < 0 || phase_shift > 1)
+ throw std::out_of_range ("phase shift ratio must be > 0 and < 1");
+
+ set_relative_rate (1.0 / interp_ratio);
+}
+
+gr_fractional_interpolator_ff::~gr_fractional_interpolator_ff()
+{
+ delete d_interp;
+}
+
+void
+gr_fractional_interpolator_ff::forecast(int noutput_items, gr_vector_int &ninput_items_required)
+{
+ unsigned ninputs = ninput_items_required.size();
+ for (unsigned i=0; i < ninputs; i++)
+
+ ninput_items_required[i] =
+ (int) ceil((noutput_items * d_mu_inc) + d_interp->ntaps());
+}
+
+int
+gr_fractional_interpolator_ff::general_work(int noutput_items,
+ gr_vector_int &ninput_items,
+ gr_vector_const_void_star &input_items,
+ gr_vector_void_star &output_items)
+{
+ const float *in = (const float *) input_items[0];
+ float *out = (float *) output_items[0];
+
+ int ii = 0; // input index
+ int oo = 0; // output index
+
+ while (oo < noutput_items) {
+
+ out[oo++] = d_interp->interpolate(&in[ii], d_mu);
+
+ double s = d_mu + d_mu_inc;
+ double f = floor (s);
+ int incr = (int) f;
+ d_mu = s - f;
+ ii += incr;
+ }
+
+ consume_each (ii);
+
+ return noutput_items;
+}