/* Effect: change sample rate  Copyright (c) 2008,12 robs@users.sourceforge.net * * This library is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation; either version 2.1 of the License, or (at * your option) any later version. * * This library 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 Lesser * General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this library; if not, write to the Free Software Foundation, * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA */ /* Resample using an interpolated poly-phase FIR with length LEN.*//* Input must be followed by LEN-1 samples. */ #define a (coef(p->shared->poly_fir_coefs, COEF_INTERP, FIR_LENGTH, phase, 0,j))#define b (coef(p->shared->poly_fir_coefs, COEF_INTERP, FIR_LENGTH, phase, 1,j))#define c (coef(p->shared->poly_fir_coefs, COEF_INTERP, FIR_LENGTH, phase, 2,j))#define d (coef(p->shared->poly_fir_coefs, COEF_INTERP, FIR_LENGTH, phase, 3,j))#if COEF_INTERP == 0  #define _ sum += a *in[j], ++j;#elif COEF_INTERP == 1  #define _ sum += (b *x + a)*in[j], ++j;#elif COEF_INTERP == 2  #define _ sum += ((c *x + b)*x + a)*in[j], ++j;#elif COEF_INTERP == 3  #define _ sum += (((d*x + c)*x + b)*x + a)*in[j], ++j;#else  #error COEF_INTERP#endif static void FUNCTION(stage_t * p, fifo_t * output_fifo){  sample_t const * input = stage_read_p(p);  int i, num_in = stage_occupancy(p), max_num_out = 1 + num_in*p->out_in_ratio;  sample_t * output = fifo_reserve(output_fifo, max_num_out); #if defined HI_PREC_CLOCK  if (p->use_hi_prec_clock) {    hi_prec_clock_t at = p->at.hi_prec_clock;    for (i = 0; (int)at < num_in; ++i, at += p->step.hi_prec_clock) {      sample_t const * in = input + (int)at;      hi_prec_clock_t fraction = at - (int)at;      int phase = fraction * (1 << PHASE_BITS);#if COEF_INTERP > 0      sample_t x = fraction * (1 << PHASE_BITS) - phase;#endif      sample_t sum = 0;      int j = 0;      CONVOLVE      output[i] = sum;    }    fifo_read(&p->fifo, (int)at, NULL);    p->at.hi_prec_clock = at - (int)at;  } else#endif  {    for (i = 0; p->at.parts.integer < num_in; ++i, p->at.all += p->step.all) {      sample_t const * in = input + p->at.parts.integer;      uint32_t fraction = p->at.parts.fraction;      int phase = fraction >> (32 - PHASE_BITS); /* high-order bits */#if COEF_INTERP > 0              /* low-order bits, scaled to [0,1) */      sample_t x = (sample_t) (fraction << PHASE_BITS) * (1 / MULT32);#endif      sample_t sum = 0;      int j = 0;      CONVOLVE      USED(j);      output[i] = sum;    }    fifo_read(&p->fifo, p->at.parts.integer, NULL);    p->at.parts.integer = 0;  }  assert(max_num_out - i >= 0);  fifo_trim_by(output_fifo, max_num_out - i);} #undef _#undef a#undef b#undef c#undef d#undef COEF_INTERP#undef CONVOLVE#undef FIR_LENGTH#undef FUNCTION#undef PHASE_BITS