124 lines
2.6 KiB
C++
124 lines
2.6 KiB
C++
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// ----------------------------------------------------------------------------
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//
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// Copyright (C) 2006-2012 Fons Adriaensen <fons@linuxaudio.org>
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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//
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// ----------------------------------------------------------------------------
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <math.h>
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#include "zita-resampler/resampler-table.h"
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using namespace ArdourZita;
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Resampler_table *Resampler_table::_list = 0;
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Resampler_mutex Resampler_table::_mutex;
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static double sinc (double x)
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{
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x = fabs (x);
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if (x < 1e-6) return 1.0;
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x *= M_PI;
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return sin (x) / x;
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}
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static double wind (double x)
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{
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x = fabs (x);
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if (x >= 1.0) return 0.0f;
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x *= M_PI;
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return 0.384 + 0.500 * cos (x) + 0.116 * cos (2 * x);
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}
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Resampler_table::Resampler_table (double fr, unsigned int hl, unsigned int np)
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: _next (0)
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, _refc (0)
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, _fr (fr)
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, _hl (hl)
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, _np (np)
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{
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unsigned int i, j;
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double t;
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float *p;
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_ctab = new float [hl * (np + 1)];
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p = _ctab;
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for (j = 0; j <= np; j++) {
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t = (double) j / (double) np;
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for (i = 0; i < hl; i++) {
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p [hl - i - 1] = (float)(fr * sinc (t * fr) * wind (t / hl));
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t += 1;
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}
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p += hl;
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}
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}
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Resampler_table::~Resampler_table (void)
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{
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delete[] _ctab;
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}
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Resampler_table*
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Resampler_table::create (double fr, unsigned int hl, unsigned int np)
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{
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Resampler_table *P;
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_mutex.lock ();
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P = _list;
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while (P) {
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if ((fr >= P->_fr * 0.999) && (fr <= P->_fr * 1.001) && (hl == P->_hl) && (np == P->_np)) {
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P->_refc++;
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_mutex.unlock ();
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return P;
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}
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P = P->_next;
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}
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P = new Resampler_table (fr, hl, np);
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P->_refc = 1;
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P->_next = _list;
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_list = P;
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_mutex.unlock ();
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return P;
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}
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void
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Resampler_table::destroy (Resampler_table *T)
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{
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Resampler_table *P, *Q;
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_mutex.lock ();
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if (T) {
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T->_refc--;
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if (T->_refc == 0) {
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P = _list;
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Q = 0;
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while (P) {
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if (P == T) {
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if (Q) Q->_next = T->_next;
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else _list = T->_next;
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break;
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}
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Q = P;
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P = P->_next;
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}
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delete T;
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}
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}
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_mutex.unlock ();
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}
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