--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.6pre17/src/spandsp/power_meter.h	Fri Jun 25 15:50:58 2010 +0200
@@ -0,0 +1,154 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * power_meter.h
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2003 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: power_meter.h,v 1.19 2009/05/19 14:15:09 steveu Exp $
+ */
+
+#if !defined(_POWER_METER_H_)
+#define _POWER_METER_H_
+
+/*! \page power_meter_page Power metering
+
+\section power_meter_page_sec_1 What does it do?
+The power metering module implements a simple IIR type running power meter. The damping
+factor of the IIR is selectable when the meter instance is created.
+
+Note that the definition of dBOv is quite vague in most places - is it peak since wave,
+peak square wave, etc.? This code is based on the well defined wording in RFC3389:
+
+"For example, in the case of a u-law system, the reference would be a square wave with
+values +/-8031, and this square wave represents 0dBov.  This translates into 6.18dBm0".
+
+\section power_meter_page_sec_2 How does it work?
+*/
+
+/*!
+    Power meter descriptor. This defines the working state for a
+    single instance of a power measurement device.
+*/
+typedef struct
+{
+    /*! The shift factor, which controls the damping of the power meter. */
+    int shift;
+
+    /*! The current power reading. */
+    int32_t reading;
+} power_meter_t;
+
+typedef struct
+{
+    power_meter_t short_term;
+    power_meter_t medium_term;
+    int signal_present;
+    int32_t surge;
+    int32_t sag;
+    int32_t min;
+} power_surge_detector_state_t;
+
+#if defined(__cplusplus)
+extern "C"
+{
+#endif
+
+/*! Initialise a power meter context.
+    \brief Initialise a power meter context.
+    \param s The power meter context.
+    \param shift The shift to be used by the IIR filter.
+    \return The power meter context. */
+SPAN_DECLARE(power_meter_t *) power_meter_init(power_meter_t *s, int shift);
+
+SPAN_DECLARE(int) power_meter_release(power_meter_t *s);
+
+SPAN_DECLARE(int) power_meter_free(power_meter_t *s);
+
+/*! Change the damping factor of a power meter context.
+    \brief Change the damping factor of a power meter context.
+    \param s The power meter context.
+    \param shift The new shift to be used by the IIR filter.
+    \return The power meter context. */
+SPAN_DECLARE(power_meter_t *) power_meter_damping(power_meter_t *s, int shift);
+
+/*! Update a power meter.
+    \brief Update a power meter.
+    \param s The power meter context.
+    \param amp The amplitude of the new audio sample.
+    \return The current power meter reading. */
+SPAN_DECLARE(int32_t) power_meter_update(power_meter_t *s, int16_t amp);
+
+/*! Get the current power meter reading.
+    \brief Get the current power meter reading.
+    \param s The power meter context.
+    \return The current power meter reading. */
+SPAN_DECLARE(int32_t) power_meter_current(power_meter_t *s);
+
+/*! Get the current power meter reading, in dBm0.
+    \brief Get the current power meter reading, in dBm0.
+    \param s The power meter context.
+    \return The current power meter reading, in dBm0. */
+SPAN_DECLARE(float) power_meter_current_dbm0(power_meter_t *s);
+
+/*! Get the current power meter reading, in dBOv.
+    \brief Get the current power meter reading, in dBOv.
+    \param s The power meter context.
+    \return The current power meter reading, in dBOv. */
+SPAN_DECLARE(float) power_meter_current_dbov(power_meter_t *s);
+
+/*! Get the power meter reading which represents a specified power level in dBm0.
+    \brief Get the current power meter reading, in dBm0.
+    \param level A power level, in dB0m.
+    \return The equivalent power meter reading. */
+SPAN_DECLARE(int32_t) power_meter_level_dbm0(float level);
+
+/*! Get the power meter reading which represents a specified power level in dBOv.
+    \brief Get the current power meter reading, in dBOv.
+    \param level A power level, in dBOv.
+    \return The equivalent power meter reading. */
+SPAN_DECLARE(int32_t) power_meter_level_dbov(float level);
+
+SPAN_DECLARE(int32_t) power_surge_detector(power_surge_detector_state_t *s, int16_t amp);
+
+/*! Get the current surge detector short term meter reading, in dBm0.
+    \brief Get the current surge detector meter reading, in dBm0.
+    \param s The power surge detector context.
+    \return The current power surge detector power reading, in dBm0. */
+SPAN_DECLARE(float) power_surge_detector_current_dbm0(power_surge_detector_state_t *s);
+
+/*! Get the current surge detector short term meter reading, in dBOv.
+    \brief Get the current surge detector meter reading, in dBOv.
+    \param s The power surge detector context.
+    \return The current power surge detector power reading, in dBOv. */
+SPAN_DECLARE(float) power_surge_detector_current_dbov(power_surge_detector_state_t *s);
+
+SPAN_DECLARE(power_surge_detector_state_t *) power_surge_detector_init(power_surge_detector_state_t *s, float min, float surge);
+
+SPAN_DECLARE(int) power_surge_detector_release(power_surge_detector_state_t *s);
+
+SPAN_DECLARE(int) power_surge_detector_free(power_surge_detector_state_t *s);
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif
+/*- End of file ------------------------------------------------------------*/