--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.6pre17/src/spandsp/silence_gen.h	Fri Jun 25 15:50:58 2010 +0200
@@ -0,0 +1,143 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * silence_gen.c - A silence generator, for inserting timed silences.
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2006 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: silence_gen.h,v 1.19 2009/09/04 14:38:47 steveu Exp $
+ */
+
+#if !defined(_SPANDSP_SILENCE_GEN_H_)
+#define _SPANDSP_SILENCE_GEN_H_
+
+typedef struct silence_gen_state_s silence_gen_state_t;
+
+#if defined(__cplusplus)
+extern "C"
+{
+#endif
+
+/*! Generate a block of silent audio samples.
+    \brief Generate a block of silent audio samples.
+    \param s The silence generator context.
+    \param amp The audio sample buffer.
+    \param max_len The number of samples to be generated.
+    \return The number of samples actually generated. This will be zero when
+            there is nothing to send.
+*/
+SPAN_DECLARE_NONSTD(int) silence_gen(silence_gen_state_t *s, int16_t *amp, int max_len);
+
+/*! Set a silence generator context to output continuous silence.
+    \brief Set a silence generator context to output continuous silence.
+    \param s The silence generator context.
+*/
+SPAN_DECLARE(void) silence_gen_always(silence_gen_state_t *s);
+
+/*! Set a silence generator context to output a specified period of silence.
+    \brief Set a silence generator context to output a specified period of silence.
+    \param s The silence generator context.
+    \param silent_samples The number of samples to be generated.
+*/
+SPAN_DECLARE(void) silence_gen_set(silence_gen_state_t *s, int silent_samples);
+
+/*! Alter the period of a silence generator context by a specified amount.
+    \brief Alter the period of a silence generator context by a specified amount.
+    \param s The silence generator context.
+    \param silent_samples The number of samples to change the setting by. A positive number
+                          increases the duration. A negative number reduces it. The duration
+                          is prevented from going negative.
+*/
+SPAN_DECLARE(void) silence_gen_alter(silence_gen_state_t *s, int silent_samples);
+
+/*! Find how long a silence generator context has to run.
+    \brief Find how long a silence generator context has to run.
+    \param s The silence generator context.
+    \return The number of samples remaining.
+*/
+SPAN_DECLARE(int) silence_gen_remainder(silence_gen_state_t *s);
+
+/*! Find the total silence generated to date by a silence generator context.
+    \brief Find the total silence generated to date.
+    \param s The silence generator context.
+    \return The number of samples generated.
+*/
+SPAN_DECLARE(int) silence_gen_generated(silence_gen_state_t *s);
+
+/*! Change the status reporting function associated with a silence generator context.
+    \brief Change the status reporting function associated with a silence generator context.
+    \param s The silence generator context.
+    \param handler The callback routine used to report status changes.
+    \param user_data An opaque pointer. */
+SPAN_DECLARE(void) silence_gen_status_handler(silence_gen_state_t *s, modem_tx_status_func_t handler, void *user_data);
+
+/*! Initialise a timed silence generator context.
+    \brief Initialise a timed silence generator context.
+    \param s The silence generator context.
+    \param silent_samples The initial number of samples to set the silence to.
+    \return A pointer to the silence generator context.
+*/
+SPAN_DECLARE(silence_gen_state_t *) silence_gen_init(silence_gen_state_t *s, int silent_samples);
+
+SPAN_DECLARE(int) silence_gen_release(silence_gen_state_t *s);
+
+SPAN_DECLARE(int) silence_gen_free(silence_gen_state_t *s);
+
+/* The following dummy routines, to absorb data, don't really have a proper home,
+   so they have been put here. */
+
+/*! A dummy routine to use as a receive callback, when we aren't really
+    trying to process what is received. It just absorbs and ignores the
+    data.
+    \brief Dummy receive callback.
+    \param user_data The context.
+    \param amp The signal.buffer
+    \param len The length of the signal buffer
+    \return 0.
+*/
+SPAN_DECLARE_NONSTD(int) span_dummy_rx(void *user_data, const int16_t amp[], int len);
+
+/*! A dummy routine to use as a signal modifier callback, when we aren't
+    really trying to process the signal. It just returns without affecting
+    anything.
+    \brief Dummy signal modifier callback.
+    \param user_data The context.
+    \param amp The signal.buffer
+    \param len The length of the signal buffer
+    \return 0.
+*/
+SPAN_DECLARE(int) span_dummy_mod(void *user_data, int16_t amp[], int len);
+
+/*! A dummy routine to use as a receive fillin callback, when we aren't really
+    trying to process what is received. It just absorbs and ignores the
+    request.
+    \brief Dummy receive fillin callback.
+    \param user_data The context.
+    \param len The length of the signal buffer
+    \return 0.
+*/
+SPAN_DECLARE_NONSTD(int) span_dummy_rx_fillin(void *user_data, int len);
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif
+/*- End of file ------------------------------------------------------------*/