src/rate_poly_fir0.h

   1 /* Effect: change sample rate  Copyright (c) 2008,12 robs@users.sourceforge.net
   2  *
   3  * This library is free software; you can redistribute it and/or modify it
   4  * under the terms of the GNU Lesser General Public License as published by
   5  * the Free Software Foundation; either version 2.1 of the License, or (at
   6  * your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public License
  14  * along with this library; if not, write to the Free Software Foundation,
  15  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  16  */
  17
  18 /* Resample using a non-interpolated poly-phase FIR with length LEN.*/
  19 /* Input must be followed by LEN-1 samples. */
  20
  21 #define _ sum += (coef(p->shared->poly_fir_coefs, 0, FIR_LENGTH, divided.rem, 0, j)) *at[j], ++j;
  22
  23 static void FUNCTION(stage_t * p, fifo_t * output_fifo)
  24 {
  25   sample_t const * input = stage_read_p(p);
  26   int i, num_in = stage_occupancy(p), max_num_out = 1 + num_in*p->out_in_ratio;
  27   sample_t * output = fifo_reserve(output_fifo, max_num_out);
  28   div_t divided2;
  29
  30   for (i = 0; p->at.parts.integer < num_in * p->L; ++i, p->at.parts.integer += p->step.parts.integer) {
  31     div_t divided = div(p->at.parts.integer, p->L);
  32     sample_t const * at = input + divided.quot;
  33     sample_t sum = 0;
  34     int j = 0;
  35     CONVOLVE
  36     output[i] = sum;
  37   }
  38   assert(max_num_out - i >= 0);
  39   fifo_trim_by(output_fifo, max_num_out - i);
  40   divided2 = div(p->at.parts.integer, p->L);
  41   fifo_read(&p->fifo, divided2.quot, NULL);
  42   p->at.parts.integer = divided2.rem;
  43 }
  44
  45 #undef _
  46 #undef CONVOLVE
  47 #undef FIR_LENGTH
  48 #undef FUNCTION