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83 lines
2.6 KiB
C
83 lines
2.6 KiB
C
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/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 1999 - 2005, Digium, Inc.
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*
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* Mark Spencer <markster@digium.com>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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* \brief TTY/TDD Generation support
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* \note Includes code and algorithms from the Zapata library.
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*/
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#ifndef _ASTERISK_TDD_H
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#define _ASTERISK_TDD_H
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#define TDD_BYTES_PER_CHAR 2700
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struct tdd_state;
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typedef struct tdd_state TDDSTATE;
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/*! CallerID Initialization */
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/*!
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* Initializes the TDD system. Mostly stuff for inverse FFT
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*/
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void tdd_init(void);
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/*! Generates a CallerID FSK stream in ulaw format suitable for transmission. */
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/*!
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* \param tdd tdd structure
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* \param buf Buffer to use. This needs to be large enough to accomodate all the generated samples.
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* \param string This is the string to send.
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* This function creates a stream of TDD data in ulaw format. It returns the size
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* (in bytes) of the data (if it returns a size of 0, there is probably an error)
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*/
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int tdd_generate(struct tdd_state *tdd, unsigned char *buf, const char *string);
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/*! Create a TDD state machine */
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/*!
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* This function returns a malloc'd instance of the tdd_state data structure.
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* Returns a pointer to a malloc'd tdd_state structure, or NULL on error.
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*/
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struct tdd_state *tdd_new(void);
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/*! Read samples into the state machine, and return character (if any). */
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/*!
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* \param tdd Which state machine to act upon
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* \param ubuf containing your samples
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* \param samples number of samples contained within the buffer.
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*
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* Send received audio to the TDD demodulator.
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* Returns -1 on error, 0 for "needs more samples",
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* and > 0 (the character) if reception of a character is complete.
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*/
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int tdd_feed(struct tdd_state *tdd, unsigned char *ubuf, int samples);
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/*! Free a TDD state machine */
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/*!
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* \param tdd This is the tdd_state state machine to free
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* This function frees tdd_state tdd.
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*/
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void tdd_free(struct tdd_state *tdd);
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/*! Generate Echo Canceller diable tone (2100HZ) */
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/*!
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* \param outbuf This is the buffer to receive the tone data
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* \param len This is the length (in samples) of the tone data to generate
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* Returns 0 if no error, and -1 if error.
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*/
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int ast_tdd_gen_ecdisa(unsigned char *outbuf, int len);
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#endif /* _ASTERISK_TDD_H */
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