00001 /* 00002 * Asterisk -- An open source telephony toolkit. 00003 * 00004 * Copyright (C) 1999 - 2005, Digium, Inc. 00005 * 00006 * Mark Spencer <markster@digium.com> 00007 * 00008 * See http://www.asterisk.org for more information about 00009 * the Asterisk project. Please do not directly contact 00010 * any of the maintainers of this project for assistance; 00011 * the project provides a web site, mailing lists and IRC 00012 * channels for your use. 00013 * 00014 * This program is free software, distributed under the terms of 00015 * the GNU General Public License Version 2. See the LICENSE file 00016 * at the top of the source tree. 00017 */ 00018 00019 /*! \file 00020 * \brief TTY/TDD Generation support 00021 * \note Includes code and algorithms from the Zapata library. 00022 */ 00023 00024 #ifndef _ASTERISK_TDD_H 00025 #define _ASTERISK_TDD_H 00026 00027 #define TDD_BYTES_PER_CHAR 2700 00028 00029 struct tdd_state; 00030 typedef struct tdd_state TDDSTATE; 00031 00032 /*! CallerID Initialization */ 00033 /*! 00034 * Initializes the TDD system. Mostly stuff for inverse FFT 00035 */ 00036 void tdd_init(void); 00037 00038 /*! Generates a CallerID FSK stream in ulaw format suitable for transmission. */ 00039 /*! 00040 * \param tdd tdd structure 00041 * \param buf Buffer to use. This needs to be large enough to accomodate all the generated samples. 00042 * \param string This is the string to send. 00043 * This function creates a stream of TDD data in ulaw format. It returns the size 00044 * (in bytes) of the data (if it returns a size of 0, there is probably an error) 00045 */ 00046 int tdd_generate(struct tdd_state *tdd, unsigned char *buf, const char *string); 00047 00048 /*! Create a TDD state machine */ 00049 /*! 00050 * This function returns a malloc'd instance of the tdd_state data structure. 00051 * Returns a pointer to a malloc'd tdd_state structure, or NULL on error. 00052 */ 00053 struct tdd_state *tdd_new(void); 00054 00055 /*! Read samples into the state machine, and return character (if any). */ 00056 /*! 00057 * \param tdd Which state machine to act upon 00058 * \param ubuf containing your samples 00059 * \param samples number of samples contained within the buffer. 00060 * 00061 * Send received audio to the TDD demodulator. 00062 * Returns -1 on error, 0 for "needs more samples", 00063 * and > 0 (the character) if reception of a character is complete. 00064 */ 00065 int tdd_feed(struct tdd_state *tdd, unsigned char *ubuf, int samples); 00066 00067 /*! Free a TDD state machine */ 00068 /*! 00069 * \param tdd This is the tdd_state state machine to free 00070 * This function frees tdd_state tdd. 00071 */ 00072 void tdd_free(struct tdd_state *tdd); 00073 00074 /*! Generate Echo Canceller diable tone (2100HZ) */ 00075 /*! 00076 * \param outbuf This is the buffer to receive the tone data 00077 * \param len This is the length (in samples) of the tone data to generate 00078 * Returns 0 if no error, and -1 if error. 00079 */ 00080 int ast_tdd_gen_ecdisa(unsigned char *outbuf, int len); 00081 00082 #endif /* _ASTERISK_TDD_H */