Asterisk - The Open Source Telephony Project GIT-master-2de1a68
tdd.h
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1/*
2 * Asterisk -- An open source telephony toolkit.
3 *
4 * Copyright (C) 1999 - 2005, Digium, Inc.
5 *
6 * Mark Spencer <markster@digium.com>
7 *
8 * See http://www.asterisk.org for more information about
9 * the Asterisk project. Please do not directly contact
10 * any of the maintainers of this project for assistance;
11 * the project provides a web site, mailing lists and IRC
12 * channels for your use.
13 *
14 * This program is free software, distributed under the terms of
15 * the GNU General Public License Version 2. See the LICENSE file
16 * at the top of the source tree.
17 */
18
19/*! \file
20 * \brief TTY/TDD Generation support
21 * \note Includes code and algorithms from the Zapata library.
22 */
23
24#ifndef _ASTERISK_TDD_H
25#define _ASTERISK_TDD_H
26
27#define TDD_BYTES_PER_CHAR 2700
28
29struct tdd_state;
30typedef struct tdd_state TDDSTATE;
31
32/*! CallerID Initialization
33 * Initializes the TDD system. Mostly stuff for inverse FFT
34 */
35void tdd_init(void);
36
37/*! Generates a CallerID FSK stream in ulaw format suitable for transmission.
38 * \param tdd tdd structure
39 * \param buf Buffer to use. This needs to be large enough to accomodate all the generated samples.
40 * \param string This is the string to send.
41 * This function creates a stream of TDD data in ulaw format. It returns the size
42 * (in bytes) of the data (if it returns a size of 0, there is probably an error)
43*/
44int tdd_generate(struct tdd_state *tdd, unsigned char *buf, const char *string);
45
46/*! Create a TDD state machine
47 * This function returns a malloc'd instance of the tdd_state data structure.
48 * Returns a pointer to a malloc'd tdd_state structure, or NULL on error.
49 */
50struct tdd_state *tdd_new(void);
51
52/*! Read samples into the state machine, and return character (if any).
53 * \param tdd Which state machine to act upon
54 * \param ubuf containing your samples
55 * \param samples number of samples contained within the buffer.
56 *
57 * Send received audio to the TDD demodulator.
58 * Returns -1 on error, 0 for "needs more samples",
59 * and > 0 (the character) if reception of a character is complete.
60 */
61int tdd_feed(struct tdd_state *tdd, unsigned char *ubuf, int samples);
62
63/*! Free a TDD state machine
64 * \param tdd This is the tdd_state state machine to free
65 * This function frees tdd_state tdd.
66 */
67void tdd_free(struct tdd_state *tdd);
68
69/*! Generate Echo Canceller disable tone (2100HZ)
70 * \param outbuf This is the buffer to receive the tone data
71 * \param len This is the length (in samples) of the tone data to generate
72 * Returns 0 if no error, and -1 if error.
73 */
74int ast_tdd_gen_ecdisa(unsigned char *outbuf, int len);
75
76
77/*! Generate hold tone
78 * \param buf This is the buffer to receive the tone data
79*/
80int tdd_gen_holdtone(unsigned char* buf);
81
82#endif /* _ASTERISK_TDD_H */
char buf[BUFSIZE]
Definition: eagi_proxy.c:66
static int len(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t buflen)
Definition: tdd.c:47
int tdd_generate(struct tdd_state *tdd, unsigned char *buf, const char *string)
Definition: tdd.c:296
int tdd_gen_holdtone(unsigned char *buf)
Definition: tdd.c:285
struct tdd_state * tdd_new(void)
Definition: tdd.c:103
void tdd_free(struct tdd_state *tdd)
Definition: tdd.c:218
int ast_tdd_gen_ecdisa(unsigned char *outbuf, int len)
Definition: tdd.c:148
void tdd_init(void)
Definition: tdd.c:94
int tdd_feed(struct tdd_state *tdd, unsigned char *ubuf, int samples)
Definition: tdd.c:161