--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.3/spandsp-0.0.3/src/spandsp/tone_detect.h	Fri Jun 25 16:00:21 2010 +0200
@@ -0,0 +1,108 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * tone_detect.h - General telephony tone detection, and specific
+ *                 detection of Bell MF, and MFC/R2.
+ *
+ * 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 General Public License version 2, 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU 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 1.27 2006/10/24 13:45:28 steveu Exp $
+ */
+
+#if !defined(_TONE_DETECT_H_)
+#define _TONE_DETECT_H_
+
+/*!
+    Floating point Goertzel filter descriptor.
+*/
+typedef struct
+{
+    float fac;
+    int samples;
+} goertzel_descriptor_t;
+
+/*!
+    Floating point Goertzel filter state descriptor.
+*/
+typedef struct
+{
+    float v2;
+    float v3;
+    float fac;
+    int samples;
+    int current_sample;
+} goertzel_state_t;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*! \brief Create a descriptor for use with either a Goertzel transform */
+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. */
+goertzel_state_t *goertzel_init(goertzel_state_t *s,
+                                goertzel_descriptor_t *t);
+
+/*! \brief Reset the state of a Goertzel transform.
+    \param s The Goertzel context.
+    \param t The Goertzel descriptor.
+    \return A pointer to the Goertzel state. */
+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 */
+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. */
+float goertzel_result(goertzel_state_t *s);
+
+/*! \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)
+{
+    float v1;
+
+    v1 = s->v2;
+    s->v2 = s->v3;
+    s->v3 = s->fac*s->v2 - v1 + amp;
+    s->current_sample++;
+}
+/*- End of function --------------------------------------------------------*/
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+/*- End of file ------------------------------------------------------------*/