Mercurial > hg > audiostuff
comparison spandsp-0.0.6pre17/src/spandsp/v42bis.h @ 4:26cd8f1ef0b1
import spandsp-0.0.6pre17
author | Peter Meerwald <pmeerw@cosy.sbg.ac.at> |
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date | Fri, 25 Jun 2010 15:50:58 +0200 |
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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 ------------------------------------------------------------*/ |