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comparison spandsp-0.0.6pre17/src/spandsp/v42bis.h @ 4:26cd8f1ef0b1

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import spandsp-0.0.6pre17
author Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date Fri, 25 Jun 2010 15:50:58 +0200
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3:c6c5a16ce2f2 4:26cd8f1ef0b1
1 /*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * v42bis.h
5 *
6 * Written by Steve Underwood <steveu@coppice.org>
7 *
8 * Copyright (C) 2005 Steve Underwood
9 *
10 * All rights reserved.
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Lesser General Public License version 2.1,
14 * as published by the Free Software Foundation.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with this program; if not, write to the Free Software
23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 *
25 * $Id: v42bis.h,v 1.27 2009/04/11 18:11:19 steveu Exp $
26 */
27
28 /*! \page v42bis_page V.42bis modem data compression
29 \section v42bis_page_sec_1 What does it do?
30 The v.42bis specification defines a data compression scheme, to work in
31 conjunction with the error correction scheme defined in V.42.
32
33 \section v42bis_page_sec_2 How does it work?
34 */
35
36 #if !defined(_SPANDSP_V42BIS_H_)
37 #define _SPANDSP_V42BIS_H_
38
39 #define V42BIS_MAX_BITS 12
40 #define V42BIS_MAX_CODEWORDS 4096 /* 2^V42BIS_MAX_BITS */
41 #define V42BIS_TABLE_SIZE 5021 /* This should be a prime >(2^V42BIS_MAX_BITS) */
42 #define V42BIS_MAX_STRING_SIZE 250
43
44 enum
45 {
46 V42BIS_P0_NEITHER_DIRECTION = 0,
47 V42BIS_P0_INITIATOR_RESPONDER,
48 V42BIS_P0_RESPONDER_INITIATOR,
49 V42BIS_P0_BOTH_DIRECTIONS
50 };
51
52 enum
53 {
54 V42BIS_COMPRESSION_MODE_DYNAMIC = 0,
55 V42BIS_COMPRESSION_MODE_ALWAYS,
56 V42BIS_COMPRESSION_MODE_NEVER
57 };
58
59 typedef void (*v42bis_frame_handler_t)(void *user_data, const uint8_t *pkt, int len);
60 typedef void (*v42bis_data_handler_t)(void *user_data, const uint8_t *buf, int len);
61
62 /*!
63 V.42bis compression/decompression descriptor. This defines the working state for a
64 single instance of V.42bis compress/decompression.
65 */
66 typedef struct v42bis_state_s v42bis_state_t;
67
68 #if defined(__cplusplus)
69 extern "C"
70 {
71 #endif
72
73 /*! Compress a block of octets.
74 \param s The V.42bis context.
75 \param buf The data to be compressed.
76 \param len The length of the data buffer.
77 \return 0 */
78 SPAN_DECLARE(int) v42bis_compress(v42bis_state_t *s, const uint8_t *buf, int len);
79
80 /*! Flush out any data remaining in a compression buffer.
81 \param s The V.42bis context.
82 \return 0 */
83 SPAN_DECLARE(int) v42bis_compress_flush(v42bis_state_t *s);
84
85 /*! Decompress a block of octets.
86 \param s The V.42bis context.
87 \param buf The data to be decompressed.
88 \param len The length of the data buffer.
89 \return 0 */
90 SPAN_DECLARE(int) v42bis_decompress(v42bis_state_t *s, const uint8_t *buf, int len);
91
92 /*! Flush out any data remaining in the decompression buffer.
93 \param s The V.42bis context.
94 \return 0 */
95 SPAN_DECLARE(int) v42bis_decompress_flush(v42bis_state_t *s);
96
97 /*! Set the compression mode.
98 \param s The V.42bis context.
99 \param mode One of the V.42bis compression modes -
100 V42BIS_COMPRESSION_MODE_DYNAMIC,
101 V42BIS_COMPRESSION_MODE_ALWAYS,
102 V42BIS_COMPRESSION_MODE_NEVER */
103 SPAN_DECLARE(void) v42bis_compression_control(v42bis_state_t *s, int mode);
104
105 /*! Initialise a V.42bis context.
106 \param s The V.42bis context.
107 \param negotiated_p0 The negotiated P0 parameter, from the V.42bis spec.
108 \param negotiated_p1 The negotiated P1 parameter, from the V.42bis spec.
109 \param negotiated_p2 The negotiated P2 parameter, from the V.42bis spec.
110 \param frame_handler Frame callback handler.
111 \param frame_user_data An opaque pointer passed to the frame callback handler.
112 \param max_frame_len The maximum length that should be passed to the frame handler.
113 \param data_handler data callback handler.
114 \param data_user_data An opaque pointer passed to the data callback handler.
115 \param max_data_len The maximum length that should be passed to the data handler.
116 \return The V.42bis context. */
117 SPAN_DECLARE(v42bis_state_t *) v42bis_init(v42bis_state_t *s,
118 int negotiated_p0,
119 int negotiated_p1,
120 int negotiated_p2,
121 v42bis_frame_handler_t frame_handler,
122 void *frame_user_data,
123 int max_frame_len,
124 v42bis_data_handler_t data_handler,
125 void *data_user_data,
126 int max_data_len);
127
128 /*! Release a V.42bis context.
129 \param s The V.42bis context.
130 \return 0 if OK */
131 SPAN_DECLARE(int) v42bis_release(v42bis_state_t *s);
132
133 /*! Free a V.42bis context.
134 \param s The V.42bis context.
135 \return 0 if OK */
136 SPAN_DECLARE(int) v42bis_free(v42bis_state_t *s);
137
138 #if defined(__cplusplus)
139 }
140 #endif
141
142 #endif
143 /*- End of file ------------------------------------------------------------*/

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