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  • /*
     * Asterisk -- An open source telephony toolkit.
     *
     * Copyright (C) 2007, 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 Technology independent volume control
     *
     * \author Joshua Colp <jcolp@digium.com> 
     *
     * \ingroup functions
     *
     */
    
    #include "asterisk.h"
    
    ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
    
    #include "asterisk/module.h"
    #include "asterisk/channel.h"
    #include "asterisk/pbx.h"
    #include "asterisk/utils.h"
    #include "asterisk/audiohook.h"
    
    struct volume_information {
    	struct ast_audiohook audiohook;
    	int tx_gain;
    	int rx_gain;
    };
    
    static void destroy_callback(void *data)
    {
    	struct volume_information *vi = data;
    
    	/* Destroy the audiohook, and destroy ourselves */
    	ast_audiohook_destroy(&vi->audiohook);
    	free(vi);
    
    	return;
    }
    
    /*! \brief Static structure for datastore information */
    static const struct ast_datastore_info volume_datastore = {
    
    	.type = "volume",
    	.destroy = destroy_callback
    
    };
    
    static int volume_callback(struct ast_audiohook *audiohook, struct ast_channel *chan, struct ast_frame *frame, enum ast_audiohook_direction direction)
    {
    	struct ast_datastore *datastore = NULL;
    	struct volume_information *vi = NULL;
    	int *gain = NULL;
    
    	/* If the audiohook is stopping it means the channel is shutting down.... but we let the datastore destroy take care of it */
    	if (audiohook->status == AST_AUDIOHOOK_STATUS_DONE)
    		return 0;
    
    	/* Grab datastore which contains our gain information */
    	if (!(datastore = ast_channel_datastore_find(chan, &volume_datastore, NULL)))
    		return 0;
    
    	vi = datastore->data;
    
    	/* If this is DTMF then allow them to increase/decrease the gains */
    	if (frame->frametype == AST_FRAME_DTMF) {
    		/* Only use DTMF coming from the source... not going to it */
    		if (direction != AST_AUDIOHOOK_DIRECTION_READ)
    			return 0;
    		if (frame->subclass == '*') {
    			vi->tx_gain += 1;
    			vi->rx_gain += 1;
    		} else if (frame->subclass == '#') {
    			vi->tx_gain -= 1;
    			vi->rx_gain -= 1;
    		}
    	} else if (frame->frametype == AST_FRAME_VOICE) {
    		/* Based on direction of frame grab the gain, and confirm it is applicable */
    		if (!(gain = (direction == AST_AUDIOHOOK_DIRECTION_READ) ? &vi->rx_gain : &vi->tx_gain) || !*gain)
    			return 0;
    		/* Apply gain to frame... easy as pi */
    		ast_frame_adjust_volume(frame, *gain);
    	}
    
    	return 0;
    }
    
    static int volume_write(struct ast_channel *chan, const char *cmd, char *data, const char *value)
    {
    	struct ast_datastore *datastore = NULL;
    	struct volume_information *vi = NULL;
    	int is_new = 0;
    
    	if (!(datastore = ast_channel_datastore_find(chan, &volume_datastore, NULL))) {
    		/* Allocate a new datastore to hold the reference to this volume and audiohook information */
    
    		if (!(datastore = ast_datastore_alloc(&volume_datastore, NULL)))
    
    			return 0;
    		if (!(vi = ast_calloc(1, sizeof(*vi)))) {
    
    			return 0;
    		}
    		ast_audiohook_init(&vi->audiohook, AST_AUDIOHOOK_TYPE_MANIPULATE, "Volume");
    		vi->audiohook.manipulate_callback = volume_callback;
    		ast_set_flag(&vi->audiohook, AST_AUDIOHOOK_WANTS_DTMF);
    		is_new = 1;
    	} else {
    		vi = datastore->data;
    	}
    
    	/* Adjust gain on volume information structure */
    	if (!strcasecmp(data, "tx"))
    		vi->tx_gain = atoi(value);
    	else if (!strcasecmp(data, "rx"))
    		vi->rx_gain = atoi(value);
    
    	if (is_new) {
    		datastore->data = vi;
    		ast_channel_datastore_add(chan, datastore);
    		ast_audiohook_attach(chan, &vi->audiohook);
    	}
    
    	return 0;
    }
    
    static struct ast_custom_function volume_function = {
    	.name = "VOLUME",
    	.synopsis = "Set the TX or RX volume of a channel",
    	.syntax = "VOLUME(TX|RX)",
    	.desc =
    	"  The VOLUME function can be used to increase or decrease the tx or\n"
    	"rx gain of any channel.  For example:\n"
    	"  Set(VOLUME(TX)=3)\n"
    	"  Set(VOLUME(RX)=2)\n",
    	.write = volume_write,
    };
    
    static int unload_module(void)
    {
    	return ast_custom_function_unregister(&volume_function);
    }
    
    static int load_module(void)
    {
    	return ast_custom_function_register(&volume_function);
    }
    
    AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Technology independent volume control");