spandsp  0.0.6
v42bis.h
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 
26 /*! \page v42bis_page V.42bis modem data compression
27 \section v42bis_page_sec_1 What does it do?
28 The v.42bis specification defines a data compression scheme, to work in
29 conjunction with the error correction scheme defined in V.42.
30 
31 \section v42bis_page_sec_2 How does it work?
32 */
33 
34 #if !defined(_SPANDSP_V42BIS_H_)
35 #define _SPANDSP_V42BIS_H_
36 
37 #define V42BIS_MIN_STRING_SIZE 6
38 #define V42BIS_MAX_STRING_SIZE 250
39 #define V42BIS_MIN_DICTIONARY_SIZE 512
40 #define V42BIS_MAX_BITS 12
41 #define V42BIS_MAX_CODEWORDS 4096 /* 2^V42BIS_MAX_BITS */
42 #define V42BIS_TABLE_SIZE 5021 /* This should be a prime >(2^V42BIS_MAX_BITS) */
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 ------------------------------------------------------------*/
int v42bis_free(v42bis_state_t *s)
Definition: v42bis.c:716
int v42bis_decompress_flush(v42bis_state_t *s)
Definition: v42bis.c:586
int v42bis_decompress(v42bis_state_t *s, const uint8_t *buf, int len)
Definition: v42bis.c:384
void v42bis_compression_control(v42bis_state_t *s, int mode)
Definition: v42bis.c:618
Definition: private/v42bis.h:130
int v42bis_compress(v42bis_state_t *s, const uint8_t *buf, int len)
Definition: v42bis.c:115
v42bis_state_t * v42bis_init(v42bis_state_t *s, int negotiated_p0, int negotiated_p1, int negotiated_p2, v42bis_frame_handler_t frame_handler, void *frame_user_data, int max_frame_len, v42bis_data_handler_t data_handler, void *data_user_data, int max_data_len)
Definition: v42bis.c:633
int v42bis_compress_flush(v42bis_state_t *s)
Definition: v42bis.c:338
int v42bis_release(v42bis_state_t *s)
Definition: v42bis.c:710