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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2006, Digium, Inc.
 *
 * Joshua Colp <jcolp@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 * \brief Generic Speech Recognition API
 */

#ifndef _ASTERISK_SPEECH_H
#define _ASTERISK_SPEECH_H

#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif

/* Speech structure flags */
#define AST_SPEECH_QUIET (1 << 0) /* Quiet down output... they are talking */

/* Speech structure states - in order of expected change */
#define AST_SPEECH_STATE_NOT_READY 0 /* Not ready to accept audio */
#define AST_SPEECH_STATE_READY 1 /* Accepting audio */
#define AST_SPEECH_STATE_WAIT 2 /* Wait for results to become available */
#define AST_SPEECH_STATE_DONE 3 /* Processing is done */

/* Speech structure */
struct ast_speech {
	/*! Structure lock */
	ast_mutex_t lock;
	/*! Set flags */
	unsigned int flags;
	/*! Processing sound (used when engine is processing audio and getting results) */
	char *processing_sound;
	/*! Current state of structure */
	int state;
	/*! Expected write format */
	int format;
	/*! Data for speech engine */
	void *data;
	/*! Pointer to the engine used by this speech structure */
	struct ast_speech_engine *engine;
};
  
/* Speech recognition engine structure */
struct ast_speech_engine {
	/*! Name of speech engine */
	char *name;
	/*! Set up the speech structure within the engine */
	int (*new)(struct ast_speech *speech);
	/*! Destroy any data set on the speech structure by the engine */
	int (*destroy)(struct ast_speech *speech);
	/*! Load a local grammar on the speech structure */
	int (*load)(struct ast_speech *speech, char *grammar_name, char *grammar);
	/*! Unload a local grammar */
	int (*unload)(struct ast_speech *speech, char *grammar_name);
	/*! Activate a loaded grammar */
	int (*activate)(struct ast_speech *speech, char *grammar_name);
	/*! Deactivate a loaded grammar */
	int (*deactivate)(struct ast_speech *speech, char *grammar_name);
	/*! Write audio to the speech engine */
	int (*write)(struct ast_speech *speech, void *data, int len);
	/*! Prepare engine to accept audio */
	int (*start)(struct ast_speech *speech);
	/*! Try to get results */
	struct ast_speech_result *(*get)(struct ast_speech *speech);
	/*! Accepted formats by the engine */
	int formats;
	AST_LIST_ENTRY(ast_speech_engine) list;
};

/* Result structure */
struct ast_speech_result {
	/*! Recognized text */
	char *text;
	/*! Result score */
	int score;
	/*! Next result (may not always be present) */
	struct ast_speech_result *next;
};

/*! \brief Activate a grammar on a speech structure */
int ast_speech_grammar_activate(struct ast_speech *speech, char *grammar_name);
/*! \brief Deactivate a grammar on a speech structure */
int ast_speech_grammar_deactivate(struct ast_speech *speech, char *grammar_name);
/*! \brief Load a grammar on a speech structure (not globally) */
int ast_speech_grammar_load(struct ast_speech *speech, char *grammar_name, char *grammar);
/*! \brief Unload a grammar */
int ast_speech_grammar_unload(struct ast_speech *speech, char *grammar_name);
/*! \brief Get speech recognition results */
struct ast_speech_result *ast_speech_results_get(struct ast_speech *speech);
/*! \brief Free a set of results */
int ast_speech_results_free(struct ast_speech_result *result);
/*! \brief Indicate to the speech engine that audio is now going to start being written */
void ast_speech_start(struct ast_speech *speech);
/*! \brief Create a new speech structure */
struct ast_speech *ast_speech_new(char *engine_name, int format);
/*! \brief Destroy a speech structure */
int ast_speech_destroy(struct ast_speech *speech);
/*! \brief Write audio to the speech engine */
int ast_speech_write(struct ast_speech *speech, void *data, int len);
/*! \brief Change state of a speech structure */
int ast_speech_change_state(struct ast_speech *speech, int state);
/*! \brief Register a speech recognition engine */
int ast_speech_register(struct ast_speech_engine *engine);
/*! \brief Unregister a speech recognition engine */
int ast_speech_unregister(char *engine_name);

#if defined(__cplusplus) || defined(c_plusplus)
}
#endif

#endif /* _ASTERISK_SPEECH_H */