--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.3/spandsp-0.0.3/tests/line_model.h	Fri Jun 25 16:00:21 2010 +0200
@@ -0,0 +1,154 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * line_model.h - Model a telephone line.
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2004 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: line_model.h,v 1.12 2006/10/24 13:45:29 steveu Exp $
+ */
+
+/*! \file */
+
+/*! \page line_model_page Telephone line model
+\section line_model_page_sec_1 What does it do?
+The telephone line modelling module provides simple modelling of one way and two
+way telephone lines.
+
+The path being modelled is:
+
+    -    terminal
+    -      | < hybrid echo (2-way models)
+    -      |
+    -      | < noise and filtering
+    -      |
+    -      | < hybrid echo (2-way models)
+    -     CO
+    -      |
+    -      | < A-law distortion + bulk delay
+    -      |
+    -     CO
+    -      | < hybrid echo (2-way models)
+    -      |
+    -      | < noise and filtering
+    -      |
+    -      | < hybrid echo (2-way models)
+    -    terminal
+*/
+
+#if !defined(_LINE_MODEL_H_)
+#define _LINE_MODEL_H_
+
+#define LINE_FILTER_SIZE 129
+
+/*!
+    One way line model descriptor. This holds the complete state of
+    a line model with transmission in only one direction.
+*/
+typedef struct
+{
+    codec_munge_state_t *munge;
+
+    /*! The coefficients for the near end analogue section simulation filter */
+    float *near_filter;
+    /*! The number of coefficients for the near end analogue section simulation filter */
+    int near_filter_len;
+    /*! Last transmitted samples (ring buffer, used by the line filter) */
+    float near_buf[LINE_FILTER_SIZE];
+    /*! Pointer of the last transmitted sample in buf */
+    int near_buf_ptr;
+    /*! The noise source for local analogue section of the line */
+    awgn_state_t near_noise;
+
+    /*! The bulk delay of the path, in samples */
+    int bulk_delay;
+    /*! A pointer to the current write position in the bulk delay store. */
+    int bulk_delay_ptr;
+    /*! The data store for simulating the bulk delay */
+    int16_t bulk_delay_buf[8000];
+
+    /*! The coefficients for the far end analogue section simulation filter */
+    float *far_filter;
+    /*! The number of coefficients for the far end analogue section simulation filter */
+    int far_filter_len;
+    /*! Last transmitted samples (ring buffer, used by the line filter) */
+    float far_buf[LINE_FILTER_SIZE];
+    /*! Pointer of the last transmitted sample in buf */
+    int far_buf_ptr;
+    /*! The noise source for distant analogue section of the line */
+    awgn_state_t far_noise;
+
+    /*! The scaling factor for the local CPE hybrid echo */
+    float near_cpe_hybrid_echo;
+    /*! The scaling factor for the local CO hybrid echo */
+    float near_co_hybrid_echo;
+
+    /*! The scaling factor for the far CPE hybrid echo */
+    float far_cpe_hybrid_echo;
+    /*! The scaling factor for the far CO hybrid echo */
+    float far_co_hybrid_echo;
+} one_way_line_model_state_t;
+
+/*!
+    Two way line model descriptor. This holds the complete state of
+    a line model with transmission in both directions.
+*/
+typedef struct
+{
+    one_way_line_model_state_t line1;
+    one_way_line_model_state_t line2;
+    float fout1;
+    float fout2; 
+} both_ways_line_model_state_t;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void both_ways_line_model(both_ways_line_model_state_t *s, 
+                          int16_t *output1,
+                          const int16_t *input1,
+                          int16_t *output2,
+                          const int16_t *input2,
+                          int samples);
+
+both_ways_line_model_state_t *both_ways_line_model_init(int model1,
+                                                        float noise1,
+                                                        int model2,
+                                                        float noise2,
+                                                        int codec);
+
+int both_ways_line_model_release(both_ways_line_model_state_t *s);
+
+void one_way_line_model(one_way_line_model_state_t *s, 
+                        int16_t *output,
+                        const int16_t *input,
+                        int samples);
+
+one_way_line_model_state_t *one_way_line_model_init(int model, float noise, int codec);
+
+int one_way_line_model_release(one_way_line_model_state_t *s);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+/*- End of file ------------------------------------------------------------*/