res_speech.c

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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
 *
 * \author Joshua Colp <jcolp@digium.com>
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 368751 $");

#include "asterisk/channel.h"
#include "asterisk/module.h"
#include "asterisk/lock.h"
#include "asterisk/linkedlists.h"
#include "asterisk/cli.h"
#include "asterisk/term.h"
#include "asterisk/speech.h"


static AST_RWLIST_HEAD_STATIC(engines, ast_speech_engine);
static struct ast_speech_engine *default_engine = NULL;

/*! \brief Find a speech recognition engine of specified name, if NULL then use the default one */
static struct ast_speech_engine *find_engine(const char *engine_name)
{
   struct ast_speech_engine *engine = NULL;

   /* If no name is specified -- use the default engine */
   if (ast_strlen_zero(engine_name))
      return default_engine;

   AST_RWLIST_RDLOCK(&engines);
   AST_RWLIST_TRAVERSE(&engines, engine, list) {
      if (!strcasecmp(engine->name, engine_name)) {
         break;
      }
   }
   AST_RWLIST_UNLOCK(&engines);

   return engine;
}

/*! \brief Activate a loaded (either local or global) grammar */
int ast_speech_grammar_activate(struct ast_speech *speech, const char *grammar_name)
{
   return (speech->engine->activate ? speech->engine->activate(speech, grammar_name) : -1);
}

/*! \brief Deactivate a loaded grammar on a speech structure */
int ast_speech_grammar_deactivate(struct ast_speech *speech, const char *grammar_name)
{
   return (speech->engine->deactivate ? speech->engine->deactivate(speech, grammar_name) : -1);
}

/*! \brief Load a local grammar on a speech structure */
int ast_speech_grammar_load(struct ast_speech *speech, const char *grammar_name, const char *grammar)
{
   return (speech->engine->load ? speech->engine->load(speech, grammar_name, grammar) : -1);
}

/*! \brief Unload a local grammar from a speech structure */
int ast_speech_grammar_unload(struct ast_speech *speech, const char *grammar_name)
{
   return (speech->engine->unload ? speech->engine->unload(speech, grammar_name) : -1);
}

/*! \brief Return the results of a recognition from the speech structure */
struct ast_speech_result *ast_speech_results_get(struct ast_speech *speech)
{
   return (speech->engine->get ? speech->engine->get(speech) : NULL);
}

/*! \brief Free a list of results */
int ast_speech_results_free(struct ast_speech_result *result)
{
   struct ast_speech_result *current_result = result, *prev_result = NULL;
   int res = 0;

   while (current_result != NULL) {
      prev_result = current_result;
      /* Deallocate what we can */
      if (current_result->text != NULL) {
         ast_free(current_result->text);
         current_result->text = NULL;
      }
      if (current_result->grammar != NULL) {
         ast_free(current_result->grammar);
         current_result->grammar = NULL;
      }
      /* Move on and then free ourselves */
      current_result = AST_LIST_NEXT(current_result, list);
      ast_free(prev_result);
      prev_result = NULL;
   }

   return res;
}

/*! \brief Start speech recognition on a speech structure */
void ast_speech_start(struct ast_speech *speech)
{

   /* Clear any flags that may affect things */
   ast_clear_flag(speech, AST_SPEECH_SPOKE);
   ast_clear_flag(speech, AST_SPEECH_QUIET);
   ast_clear_flag(speech, AST_SPEECH_HAVE_RESULTS);

   /* If results are on the structure, free them since we are starting again */
   if (speech->results) {
      ast_speech_results_free(speech->results);
      speech->results = NULL;
   }

   /* If the engine needs to start stuff up, do it */
   if (speech->engine->start)
      speech->engine->start(speech);

   return;
}

/*! \brief Write in signed linear audio to be recognized */
int ast_speech_write(struct ast_speech *speech, void *data, int len)
{
   /* Make sure the speech engine is ready to accept audio */
   if (speech->state != AST_SPEECH_STATE_READY)
      return -1;

   return speech->engine->write(speech, data, len);
}

/*! \brief Signal to the engine that DTMF was received */
int ast_speech_dtmf(struct ast_speech *speech, const char *dtmf)
{
   int res = 0;

   if (speech->state != AST_SPEECH_STATE_READY)
      return -1;

   if (speech->engine->dtmf != NULL) {
      res = speech->engine->dtmf(speech, dtmf);
   }

   return res;
}

/*! \brief Change an engine specific attribute */
int ast_speech_change(struct ast_speech *speech, const char *name, const char *value)
{
   return (speech->engine->change ? speech->engine->change(speech, name, value) : -1);
}

/*! \brief Create a new speech structure using the engine specified */
struct ast_speech *ast_speech_new(const char *engine_name, const struct ast_format_cap *cap)
{
   struct ast_speech_engine *engine = NULL;
   struct ast_speech *new_speech = NULL;
   struct ast_format_cap *joint = NULL;
   struct ast_format best;

   ast_format_set(&best, AST_FORMAT_SLINEAR, 0);

   /* Try to find the speech recognition engine that was requested */
   if (!(engine = find_engine(engine_name)))
      return NULL;

   /* Before even allocating the memory below do some codec negotiation, we choose the best codec possible and fall back to signed linear if possible */
   if ((joint = ast_format_cap_joint(engine->formats, cap))) {
      ast_best_codec(joint, &best);
      joint = ast_format_cap_destroy(joint);
   } else if (!ast_format_cap_iscompatible(engine->formats, &best)) {
      return NULL;
   }

   /* Allocate our own speech structure, and try to allocate a structure from the engine too */
   if (!(new_speech = ast_calloc(1, sizeof(*new_speech))))
      return NULL;

   /* Initialize the lock */
   ast_mutex_init(&new_speech->lock);

   /* Make sure no results are present */
   new_speech->results = NULL;

   /* Copy over our engine pointer */
   new_speech->engine = engine;

   /* Can't forget the format audio is going to be in */
   ast_format_copy(&new_speech->format, &best);

   /* We are not ready to accept audio yet */
   ast_speech_change_state(new_speech, AST_SPEECH_STATE_NOT_READY);

   /* Pass ourselves to the engine so they can set us up some more and if they error out then do not create a structure */
   if (engine->create(new_speech, &best)) {
      ast_mutex_destroy(&new_speech->lock);
      ast_free(new_speech);
      new_speech = NULL;
   }

   return new_speech;
}

/*! \brief Destroy a speech structure */
int ast_speech_destroy(struct ast_speech *speech)
{
   int res = 0;

   /* Call our engine so we are destroyed properly */
   speech->engine->destroy(speech);

   /* Deinitialize the lock */
   ast_mutex_destroy(&speech->lock);

   /* If results exist on the speech structure, destroy them */
   if (speech->results)
      ast_speech_results_free(speech->results);

   /* If a processing sound is set - free the memory used by it */
   if (speech->processing_sound)
      ast_free(speech->processing_sound);

   /* Aloha we are done */
   ast_free(speech);

   return res;
}

/*! \brief Change state of a speech structure */
int ast_speech_change_state(struct ast_speech *speech, int state)
{
   int res = 0;

   switch (state) {
   case AST_SPEECH_STATE_WAIT:
      /* The engine heard audio, so they spoke */
      ast_set_flag(speech, AST_SPEECH_SPOKE);
   default:
      speech->state = state;
      break;
   }

   return res;
}

/*! \brief Change the type of results we want */
int ast_speech_change_results_type(struct ast_speech *speech, enum ast_speech_results_type results_type)
{
   speech->results_type = results_type;

   return (speech->engine->change_results_type ? speech->engine->change_results_type(speech, results_type) : 0);
}

/*! \brief Register a speech recognition engine */
int ast_speech_register(struct ast_speech_engine *engine)
{
   int res = 0;

   /* Confirm the engine meets the minimum API requirements */
   if (!engine->create || !engine->write || !engine->destroy) {
      ast_log(LOG_WARNING, "Speech recognition engine '%s' did not meet minimum API requirements.\n", engine->name);
      return -1;
   }

   /* If an engine is already loaded with this name, error out */
   if (find_engine(engine->name)) {
      ast_log(LOG_WARNING, "Speech recognition engine '%s' already exists.\n", engine->name);
      return -1;
   }

   ast_verb(2, "Registered speech recognition engine '%s'\n", engine->name);

   /* Add to the engine linked list and make default if needed */
   AST_RWLIST_WRLOCK(&engines);
   AST_RWLIST_INSERT_HEAD(&engines, engine, list);
   if (!default_engine) {
      default_engine = engine;
      ast_verb(2, "Made '%s' the default speech recognition engine\n", engine->name);
   }
   AST_RWLIST_UNLOCK(&engines);

   return res;
}

/*! \brief Unregister a speech recognition engine */
int ast_speech_unregister(const char *engine_name)
{
   struct ast_speech_engine *engine = NULL;
   int res = -1;

   if (ast_strlen_zero(engine_name))
      return -1;

   AST_RWLIST_WRLOCK(&engines);
   AST_RWLIST_TRAVERSE_SAFE_BEGIN(&engines, engine, list) {
      if (!strcasecmp(engine->name, engine_name)) {
         /* We have our engine... removed it */
         AST_RWLIST_REMOVE_CURRENT(list);
         /* If this was the default engine, we need to pick a new one */
         if (engine == default_engine) {
            default_engine = AST_RWLIST_FIRST(&engines);
         }
         ast_verb(2, "Unregistered speech recognition engine '%s'\n", engine_name);
         /* All went well */
         res = 0;
         break;
      }
   }
   AST_RWLIST_TRAVERSE_SAFE_END;
   AST_RWLIST_UNLOCK(&engines);

   return res;
}

static int unload_module(void)
{
   /* We can not be unloaded */
   return -1;
}

static int load_module(void)
{
   return AST_MODULE_LOAD_SUCCESS;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS | AST_MODFLAG_LOAD_ORDER, "Generic Speech Recognition API",
      .load = load_module,
      .unload = unload_module,
      .load_pri = AST_MODPRI_APP_DEPEND,
      );