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 * Initializes the TDD system. Mostly stuff for inverse FFT 00034 */ 00035 void tdd_init(void); 00036 00037 /*! Generates a CallerID FSK stream in ulaw format suitable for transmission. 00038 * \param tdd tdd structure 00039 * \param buf Buffer to use. This needs to be large enough to accomodate all the generated samples. 00040 * \param string This is the string to send. 00041 * This function creates a stream of TDD data in ulaw format. It returns the size 00042 * (in bytes) of the data (if it returns a size of 0, there is probably an error) 00043 */ 00044 int tdd_generate(struct tdd_state *tdd, unsigned char *buf, const char *string); 00045 00046 /*! Create a TDD state machine 00047 * This function returns a malloc'd instance of the tdd_state data structure. 00048 * Returns a pointer to a malloc'd tdd_state structure, or NULL on error. 00049 */ 00050 struct tdd_state *tdd_new(void); 00051 00052 /*! Read samples into the state machine, and return character (if any). 00053 * \param tdd Which state machine to act upon 00054 * \param ubuf containing your samples 00055 * \param samples number of samples contained within the buffer. 00056 * 00057 * Send received audio to the TDD demodulator. 00058 * Returns -1 on error, 0 for "needs more samples", 00059 * and > 0 (the character) if reception of a character is complete. 00060 */ 00061 int tdd_feed(struct tdd_state *tdd, unsigned char *ubuf, int samples); 00062 00063 /*! Free a TDD state machine 00064 * \param tdd This is the tdd_state state machine to free 00065 * This function frees tdd_state tdd. 00066 */ 00067 void tdd_free(struct tdd_state *tdd); 00068 00069 /*! Generate Echo Canceller disable tone (2100HZ) 00070 * \param outbuf This is the buffer to receive the tone data 00071 * \param len This is the length (in samples) of the tone data to generate 00072 * Returns 0 if no error, and -1 if error. 00073 */ 00074 int ast_tdd_gen_ecdisa(unsigned char *outbuf, int len); 00075 00076 00077 /*! Generate hold tone 00078 * \param outbuf This is the buffer to receive the tone data 00079 */ 00080 int tdd_gen_holdtone(unsigned char* outbuf); 00081 00082 #endif /* _ASTERISK_TDD_H */