146 lines
3.3 KiB
C
146 lines
3.3 KiB
C
/*
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* filter.c -- FIR filter
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*
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* Copyright (C) 2001, 2002, 2003
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* Tomi Manninen (oh2bns@sral.fi)
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*
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* This file is part of gMFSK.
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*
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* gMFSK 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 2 of the License, or
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* (at your option) any later version.
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*
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* gMFSK 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 gMFSK; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <stdlib.h>
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#include <string.h>
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#include "hmalloc.h"
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#include "filter.h"
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#undef DEBUG
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#ifdef DEBUG
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#include <stdio.h>
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#endif
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/* ---------------------------------------------------------------------- */
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/*
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* This gets used when not optimising
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*/
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#ifndef __OPTIMIZE__
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float filter_mac(const float *a, const float *b, int size)
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{
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float sum = 0;
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int i;
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for (i = 0; i < size; i++)
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sum += a[i] * b[i];
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return sum;
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}
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#endif
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/* ---------------------------------------------------------------------- */
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struct filter *filter_init(int len, float *taps)
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{
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struct filter *f;
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f = (struct filter *) hmalloc(sizeof(struct filter));
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memset(f, 0, sizeof(struct filter));
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f->taps = (float *) hmalloc(len * sizeof(float));
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memcpy(f->taps, taps, len * sizeof(float));
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f->length = len;
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f->pointer = f->length;
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return f;
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}
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void filter_free(struct filter *f)
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{
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if (f) {
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hfree(f->taps);
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hfree(f);
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}
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}
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/* ---------------------------------------------------------------------- */
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void filter_run(struct filter *f, float in, float *out)
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{
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float *ptr = f->buffer + f->pointer++;
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*ptr = in;
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// TODO: optimize: pass filter length as constant to enable
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// using optimized __mac_c and fix the number of rounds there!
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#ifndef __HAVE_ARCH_MAC
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*out = filter_mac(ptr - f->length, f->taps, f->length);
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#else
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*out = mac(ptr - f->length, f->taps, f->length);
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#endif
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//*out = filter_mac(ptr - f->length, f->taps, 53);
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if (f->pointer == BufferLen) {
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memcpy(f->buffer,
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f->buffer + BufferLen - f->length,
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f->length * sizeof(float));
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f->pointer = f->length;
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}
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}
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short filter_run_buf(struct filter *f, short *in, float *out, int step, int len)
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{
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int id = 0;
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int od = 0;
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short maxval = 0;
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int pointer = f->pointer;
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float *buffer = f->buffer;
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while (od < len) {
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buffer[pointer] = in[id];
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// look for peak volume
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if (in[id] > maxval)
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maxval = in[id];
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#ifndef __HAVE_ARCH_MAC
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out[od] = filter_mac(&buffer[pointer - f->length], f->taps, f->length);
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#else
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out[od] = mac(&buffer[pointer - f->length], f->taps, f->length);
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#endif
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pointer++;
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/* the buffer is much smaller than the incoming chunks */
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if (pointer == BufferLen) {
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memcpy(buffer,
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buffer + BufferLen - f->length,
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f->length * sizeof(float));
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pointer = f->length;
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}
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id += step;
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od++;
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}
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f->pointer = pointer;
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return maxval;
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}
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/* ---------------------------------------------------------------------- */
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