--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.6pre17/src/spandsp/tone_detect.h	Fri Jun 25 15:50:58 2010 +0200
@@ -0,0 +1,248 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * tone_detect.h - General telephony tone detection.
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2001, 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.h,v 1.45 2009/02/10 13:06:47 steveu Exp $
+ */
+
+#if !defined(_SPANDSP_TONE_DETECT_H_)
+#define _SPANDSP_TONE_DETECT_H_
+
+/*!
+    Goertzel filter descriptor.
+*/
+struct goertzel_descriptor_s
+{
+#if defined(SPANDSP_USE_FIXED_POINT)
+    int16_t fac;
+#else
+    float fac;
+#endif
+    int samples;
+};
+
+/*!
+    Goertzel filter state descriptor.
+*/
+struct goertzel_state_s
+{
+#if defined(SPANDSP_USE_FIXED_POINT)
+    int16_t v2;
+    int16_t v3;
+    int16_t fac;
+#else
+    float v2;
+    float v3;
+    float fac;
+#endif
+    int samples;
+    int current_sample;
+};
+
+/*!
+    Goertzel filter descriptor.
+*/
+typedef struct goertzel_descriptor_s goertzel_descriptor_t;
+
+/*!
+    Goertzel filter state descriptor.
+*/
+typedef struct goertzel_state_s goertzel_state_t;
+
+#if defined(__cplusplus)
+extern "C"
+{
+#endif
+
+/*! \brief Create a descriptor for use with either a Goertzel transform */
+SPAN_DECLARE(void) make_goertzel_descriptor(goertzel_descriptor_t *t,
+                                            float freq,
+                                            int samples);
+
+/*! \brief Initialise the state of a Goertzel transform.
+    \param s The Goertzel context. If NULL, a context is allocated with malloc.
+    \param t The Goertzel descriptor.
+    \return A pointer to the Goertzel state. */
+SPAN_DECLARE(goertzel_state_t *) goertzel_init(goertzel_state_t *s,
+                                               goertzel_descriptor_t *t);
+
+SPAN_DECLARE(int) goertzel_release(goertzel_state_t *s);
+
+SPAN_DECLARE(int) goertzel_free(goertzel_state_t *s);
+
+/*! \brief Reset the state of a Goertzel transform.
+    \param s The Goertzel context. */
+SPAN_DECLARE(void) goertzel_reset(goertzel_state_t *s);
+
+/*! \brief Update the state of a Goertzel transform.
+    \param s The Goertzel context.
+    \param amp The samples to be transformed.
+    \param samples The number of samples.
+    \return The number of samples unprocessed */
+SPAN_DECLARE(int) goertzel_update(goertzel_state_t *s,
+                                  const int16_t amp[],
+                                  int samples);
+
+/*! \brief Evaluate the final result of a Goertzel transform.
+    \param s The Goertzel context.
+    \return The result of the transform. The expected result for a pure sine wave
+            signal of level x dBm0, at the very centre of the bin is:
+    [Floating point] ((samples_per_goertzel_block*32768.0/1.4142)*10^((x - DBM0_MAX_SINE_POWER)/20.0))^2
+    [Fixed point] ((samples_per_goertzel_block*256.0/1.4142)*10^((x - DBM0_MAX_SINE_POWER)/20.0))^2 */
+#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
+
+/*! \brief Update the state of a Goertzel transform.
+    \param s The Goertzel context.
+    \param amp The sample to be transformed. */
+static __inline__ void goertzel_sample(goertzel_state_t *s, int16_t amp)
+{
+#if defined(SPANDSP_USE_FIXED_POINT)
+    int16_t x;
+    int16_t v1;
+#else
+    float v1;
+#endif
+
+    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 >> 7);
+#else
+    s->v3 = s->fac*s->v2 - v1 + amp;
+#endif
+    s->current_sample++;
+}
+/*- End of function --------------------------------------------------------*/
+
+/* 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. This is sufficient for the longest Goertzel we currently use. */
+#if defined(SPANDSP_USE_FIXED_POINT)
+#define goertzel_preadjust_amp(amp) (((int16_t) amp) >> 7)
+#else
+#define goertzel_preadjust_amp(amp) ((float) amp)
+#endif
+
+/* Minimal update the state of a Goertzel transform. This is similar to
+   goertzel_sample, but more suited to blocks of Goertzels. It assumes
+   the amplitude is pre-shifted, and does not update the per-state sample
+   count.
+    \brief Update the state of a Goertzel transform.
+    \param s The Goertzel context.
+    \param amp The adjusted sample to be transformed. */
+#if defined(SPANDSP_USE_FIXED_POINT)
+static __inline__ void goertzel_samplex(goertzel_state_t *s, int16_t amp)
+#else
+static __inline__ void goertzel_samplex(goertzel_state_t *s, float amp)
+#endif
+{
+#if defined(SPANDSP_USE_FIXED_POINT)
+    int16_t x;
+    int16_t v1;
+#else
+    float v1;
+#endif
+
+    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 + amp;
+#else
+    s->v3 = s->fac*s->v2 - v1 + amp;
+#endif
+}
+/*- End of function --------------------------------------------------------*/
+
+/*! Generate a Hamming weighted coefficient set, to be used for a periodogram analysis.
+    \param coeffs The generated coefficients.
+    \param freq The frequency to be matched by the periodogram, in Hz.
+    \param sample_rate The sample rate of the signal, in samples per second.
+    \param window_len The length of the periodogram window. This must be an even number.
+    \return The number of generated coefficients.
+*/
+SPAN_DECLARE(int) periodogram_generate_coeffs(complexf_t coeffs[], float freq, int sample_rate, int window_len);
+
+/*! Generate the phase offset to be expected between successive periodograms evaluated at the 
+    specified interval.
+    \param offset A point to the generated phase offset.
+    \param freq The frequency being matched by the periodogram, in Hz.
+    \param sample_rate The sample rate of the signal, in samples per second.
+    \param interval The interval between periodograms, in samples.
+    \return The scaling factor.
+*/
+SPAN_DECLARE(float) periodogram_generate_phase_offset(complexf_t *offset, float freq, int sample_rate, int interval);
+
+/*! Evaluate a periodogram.
+    \param coeffs A set of coefficients generated by periodogram_generate_coeffs().
+    \param amp The complex amplitude of the signal.
+    \param len The length of the periodogram, in samples. This must be an even number.
+    \return The periodogram result.
+*/
+SPAN_DECLARE(complexf_t) periodogram(const complexf_t coeffs[], const complexf_t amp[], int len);
+
+/*! Prepare data for evaluating a set of periodograms.
+    \param sum A vector of sums of pairs of signal samples. This will be half the length of len.
+    \param diff A vector of differences between pairs of signal samples. This will be half the length of len.
+    \param amp The complex amplitude of the signal.
+    \param len The length of the periodogram, in samples. This must be an even number.
+    \return The length of the vectors sum and diff.
+*/
+SPAN_DECLARE(int) periodogram_prepare(complexf_t sum[], complexf_t diff[], const complexf_t amp[], int len);
+
+/*! Evaluate a periodogram, based on data prepared by periodogram_prepare(). This is more efficient
+    than using periodogram() when several periodograms are to be applied to the same signal.
+    \param coeffs A set of coefficients generated by periodogram_generate_coeffs().
+    \param sum A vector of sums produced by periodogram_prepare().
+    \param diff A vector of differences produced by periodogram_prepare().
+    \param len The length of the periodogram, in samples. This must be an even number.
+    \return The periodogram result.
+*/
+SPAN_DECLARE(complexf_t) periodogram_apply(const complexf_t coeffs[], const complexf_t sum[], const complexf_t diff[], int len);
+
+/*! Apply a phase offset, to find the frequency error between periodogram evaluations.
+    specified interval.
+    \param phase_offset A point to the expected phase offset.
+    \param scale The scaling factor to be used.
+    \param last_result A pointer to the previous periodogram result.
+    \param result A pointer to the current periodogram result.
+    \return The frequency error, in Hz.
+*/
+SPAN_DECLARE(float) periodogram_freq_error(const complexf_t *phase_offset, float scale, const complexf_t *last_result, const complexf_t *result);
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif
+/*- End of file ------------------------------------------------------------*/