--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.6pre17/src/tone_detect.c	Fri Jun 25 15:50:58 2010 +0200
@@ -0,0 +1,302 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * tone_detect.c - General telephony tone detection.
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2001-2003, 2005 Steve Underwood
+ *
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1,
+ * as published by the Free Software Foundation.
+ *
+ * This program 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 program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * $Id: tone_detect.c,v 1.53 2009/04/12 09:12:10 steveu Exp $
+ */
+ 
+/*! \file */
+
+#if defined(HAVE_CONFIG_H)
+#include "config.h"
+#endif
+
+#include <inttypes.h>
+#include <stdlib.h>
+#if defined(HAVE_TGMATH_H)
+#include <tgmath.h>
+#endif
+#if defined(HAVE_MATH_H)
+#include <math.h>
+#endif
+#include "floating_fudge.h"
+#include <string.h>
+#include <stdio.h>
+#include <time.h>
+#include <fcntl.h>
+
+#include "spandsp/telephony.h"
+#include "spandsp/complex.h"
+#include "spandsp/complex_vector_float.h"
+#include "spandsp/tone_detect.h"
+#include "spandsp/tone_generate.h"
+
+#include "spandsp/private/tone_detect.h"
+
+#if !defined(M_PI)
+/* C99 systems may not define M_PI */
+#define M_PI 3.14159265358979323846264338327
+#endif
+
+SPAN_DECLARE(void) make_goertzel_descriptor(goertzel_descriptor_t *t, float freq, int samples)
+{
+#if defined(SPANDSP_USE_FIXED_POINT)
+    t->fac = 16383.0f*2.0f*cosf(2.0f*M_PI*(freq/(float) SAMPLE_RATE));
+#else
+    t->fac = 2.0f*cosf(2.0f*M_PI*(freq/(float) SAMPLE_RATE));
+#endif
+    t->samples = samples;
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(goertzel_state_t *) goertzel_init(goertzel_state_t *s,
+                                               goertzel_descriptor_t *t)
+{
+    if (s == NULL)
+    {
+        if ((s = (goertzel_state_t *) malloc(sizeof(*s))) == NULL)
+            return NULL;
+    }
+#if defined(SPANDSP_USE_FIXED_POINT)
+    s->v2 =
+    s->v3 = 0;
+#else
+    s->v2 =
+    s->v3 = 0.0f;
+#endif
+    s->fac = t->fac;
+    s->samples = t->samples;
+    s->current_sample = 0;
+    return s;
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(int) goertzel_release(goertzel_state_t *s)
+{
+    return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(int) goertzel_free(goertzel_state_t *s)
+{
+    if (s)
+        free(s);
+    return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(void) goertzel_reset(goertzel_state_t *s)
+{
+#if defined(SPANDSP_USE_FIXED_POINT)
+    s->v2 =
+    s->v3 = 0;
+#else
+    s->v2 =
+    s->v3 = 0.0f;
+#endif
+    s->current_sample = 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(int) goertzel_update(goertzel_state_t *s,
+                                  const int16_t amp[],
+                                  int samples)
+{
+    int i;
+#if defined(SPANDSP_USE_FIXED_POINT)
+    int16_t x;
+    int16_t v1;
+#else
+    float v1;
+#endif
+
+    if (samples > s->samples - s->current_sample)
+        samples = s->samples - s->current_sample;
+    for (i = 0;  i < samples;  i++)
+    {
+        v1 = s->v2;
+        s->v2 = s->v3;
+#if defined(SPANDSP_USE_FIXED_POINT)
+        x = (((int32_t) s->fac*s->v2) >> 14);
+        /* Scale down the input signal to avoid overflows. 9 bits is enough to
+           monitor the signals of interest with adequate dynamic range and
+           resolution. In telephony we generally only start with 13 or 14 bits,
+           anyway. */
+        s->v3 = x - v1 + (amp[i] >> 7);
+#else
+        s->v3 = s->fac*s->v2 - v1 + amp[i];
+#endif
+    }
+    s->current_sample += samples;
+    return samples;
+}
+/*- End of function --------------------------------------------------------*/
+
+#if defined(SPANDSP_USE_FIXED_POINT)
+SPAN_DECLARE(int32_t) goertzel_result(goertzel_state_t *s)
+#else
+SPAN_DECLARE(float) goertzel_result(goertzel_state_t *s)
+#endif
+{
+#if defined(SPANDSP_USE_FIXED_POINT)
+    int16_t v1;
+    int32_t x;
+    int32_t y;
+#else
+    float v1;
+#endif
+
+    /* Push a zero through the process to finish things off. */
+    v1 = s->v2;
+    s->v2 = s->v3;
+#if defined(SPANDSP_USE_FIXED_POINT)
+    x = (((int32_t) s->fac*s->v2) >> 14);
+    s->v3 = x - v1;
+#else
+    s->v3 = s->fac*s->v2 - v1;
+#endif
+    /* Now calculate the non-recursive side of the filter. */
+    /* The result here is not scaled down to allow for the magnification
+       effect of the filter (the usual DFT magnification effect). */
+#if defined(SPANDSP_USE_FIXED_POINT)
+    x = (int32_t) s->v3*s->v3;
+    y = (int32_t) s->v2*s->v2;
+    x += y;
+    y = ((int32_t) s->v3*s->fac) >> 14;
+    y *= s->v2;
+    x -= y;
+    x <<= 1;
+    goertzel_reset(s);
+    /* The number returned in a floating point build will be 16384^2 times
+       as big as for a fixed point build, due to the 14 bit shifts
+       (or the square of the 7 bit shifts, depending how you look at it). */
+    return x;
+#else
+    v1 = s->v3*s->v3 + s->v2*s->v2 - s->v2*s->v3*s->fac;
+    v1 *= 2.0;
+    goertzel_reset(s);
+    return v1;
+#endif
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(complexf_t) periodogram(const complexf_t coeffs[], const complexf_t amp[], int len)
+{
+    complexf_t sum;
+    complexf_t diff;
+    complexf_t x;
+    int i;
+
+    x = complex_setf(0.0f, 0.0f);
+    for (i = 0;  i < len/2;  i++)
+    {
+        sum = complex_addf(&amp[i], &amp[len - 1 - i]);
+        diff = complex_subf(&amp[i], &amp[len - 1 - i]);
+        x.re += (coeffs[i].re*sum.re - coeffs[i].im*diff.im);
+        x.im += (coeffs[i].re*sum.im + coeffs[i].im*diff.re);
+    }
+    return x;
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(int) periodogram_prepare(complexf_t sum[], complexf_t diff[], const complexf_t amp[], int len)
+{
+    int i;
+
+    for (i = 0;  i < len/2;  i++)
+    {
+        sum[i] = complex_addf(&amp[i], &amp[len - 1 - i]);
+        diff[i] = complex_subf(&amp[i], &amp[len - 1 - i]);
+    }
+    return len/2;
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(complexf_t) periodogram_apply(const complexf_t coeffs[], const complexf_t sum[], const complexf_t diff[], int len)
+{
+    complexf_t x;
+    int i;
+
+    x = complex_setf(0.0f, 0.0f);
+    for (i = 0;  i < len/2;  i++)
+    {
+        x.re += (coeffs[i].re*sum[i].re - coeffs[i].im*diff[i].im);
+        x.im += (coeffs[i].re*sum[i].im + coeffs[i].im*diff[i].re);
+    }
+    return x;
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(int) periodogram_generate_coeffs(complexf_t coeffs[], float freq, int sample_rate, int window_len)
+{
+    float window;
+    float sum;
+    float x;
+    int i;
+
+    sum = 0.0f;
+    for (i = 0;  i < window_len/2;  i++)
+    {
+        /* Apply a Hamming window as we go */
+        window = 0.53836f - 0.46164f*cosf(2.0f*3.1415926535f*i/(window_len - 1.0f));
+        x = (i - window_len/2.0f + 0.5f)*freq*2.0f*3.1415926535f/sample_rate;
+        coeffs[i].re = cosf(x)*window;
+        coeffs[i].im = -sinf(x)*window;
+        sum += window;
+    }
+    /* Rescale for unity gain in the periodogram. The 2.0 factor is to allow for the full window,
+       rather than just the half over which we have summed the coefficients. */
+    sum = 1.0f/(2.0f*sum);
+    for (i = 0;  i < window_len/2;  i++)
+    {
+        coeffs[i].re *= sum;
+        coeffs[i].im *= sum;
+    }
+    return window_len/2;
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(float) periodogram_generate_phase_offset(complexf_t *offset, float freq, int sample_rate, int interval)
+{
+    float x;
+
+    /* The phase offset is how far the phase rotates in one frame */
+    x = 2.0f*3.1415926535f*(float) interval/(float) sample_rate;
+    offset->re = cosf(freq*x);
+    offset->im = sinf(freq*x);
+    return 1.0f/x;
+}
+/*- End of function --------------------------------------------------------*/
+
+SPAN_DECLARE(float) periodogram_freq_error(const complexf_t *phase_offset, float scale, const complexf_t *last_result, const complexf_t *result)
+{
+    complexf_t prediction;
+
+    /* Rotate the last result by the expected phasor offset to the current result. Then
+       find the difference between that predicted position, and the actual one. When
+       scaled by the current signal level, this gives us the frequency error. */
+    prediction = complex_mulf(last_result, phase_offset);
+    return scale*(result->im*prediction.re - result->re*prediction.im)/(result->re*result->re + result->im*result->im);
+}
+/*- End of function --------------------------------------------------------*/
+/*- End of file ------------------------------------------------------------*/