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38 lines
689 B
C
38 lines
689 B
C
/*
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* Contributor(s):
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*
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* Eric des Courtis <eric.des.courtis@benbria.com>
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*/
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#include <math.h>
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#ifndef __AVMD_GOERTZEL_H__
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#include "avmd_goertzel.h"
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#endif
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#ifndef __AVMD_BUFFER_H__
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#include "avmd_buffer.h"
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#endif
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extern double avmd_goertzel(circ_buffer_t *b, size_t pos, double f, size_t num)
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{
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double s = 0.0;
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double p = 0.0;
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double p2 = 0.0;
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double coeff;
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size_t i;
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coeff = 2.0 * cos(2.0 * M_PI * f);
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for (i = 0; i < num; i++) {
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/* TODO: optimize to avoid GET_SAMPLE when possible */
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s = GET_SAMPLE(b, i + pos) + (coeff * p) - p2;
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p2 = p;
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p = s;
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}
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return (p2 * p2) + (p * p) - (coeff * p2 * p);
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}
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