channel.c

					      .datalen = ast_codec_get_len(spy->read_queue.format, samples),
	};
	struct ast_frame stack_write_frame = { .frametype = AST_FRAME_VOICE,
					       .subclass = spy->write_queue.format,
					       .data = write_buf,
					       .samples = samples,
					       .datalen = ast_codec_get_len(spy->write_queue.format, samples),
	};

	/* if a flush has been requested, dump everything in whichever queue is larger */
	if (ast_test_flag(spy, CHANSPY_TRIGGER_FLUSH)) {
		if (spy->read_queue.samples > spy->write_queue.samples) {
			if (ast_test_flag(spy, CHANSPY_READ_VOLADJUST)) {
				for (result = spy->read_queue.head; result; result = result->next)
					ast_frame_adjust_volume(result, spy->read_vol_adjustment);
			}
			result = spy->read_queue.head;
			spy->read_queue.head = NULL;
			spy->read_queue.samples = 0;
			ast_clear_flag(spy, CHANSPY_TRIGGER_FLUSH);
			return result;
		} else {
			if (ast_test_flag(spy, CHANSPY_WRITE_VOLADJUST)) {
				for (result = spy->write_queue.head; result; result = result->next)
					ast_frame_adjust_volume(result, spy->write_vol_adjustment);
			}
			result = spy->write_queue.head;
			spy->write_queue.head = NULL;
			spy->write_queue.samples = 0;
			ast_clear_flag(spy, CHANSPY_TRIGGER_FLUSH);
			return result;
		}
	}

	if ((spy->read_queue.samples < samples) || (spy->write_queue.samples < samples))
		return NULL;

	/* short-circuit if both head frames have exactly what we want */
	if ((spy->read_queue.head->samples == samples) &&
	    (spy->write_queue.head->samples == samples)) {
		read_frame = spy->read_queue.head;
		spy->read_queue.head = read_frame->next;
		read_frame->next = NULL;

		write_frame = spy->write_queue.head;
		spy->write_queue.head = write_frame->next;
		write_frame->next = NULL;

		spy->read_queue.samples -= samples;
		spy->write_queue.samples -= samples;

		need_dup = 0;
	} else {
		copy_data_from_queue(&spy->read_queue, read_buf, samples);
		copy_data_from_queue(&spy->write_queue, write_buf, samples);

		read_frame = &stack_read_frame;
		write_frame = &stack_write_frame;
		need_dup = 1;
	}
	
	if (ast_test_flag(spy, CHANSPY_READ_VOLADJUST))
		ast_frame_adjust_volume(read_frame, spy->read_vol_adjustment);

	if (ast_test_flag(spy, CHANSPY_WRITE_VOLADJUST))
		ast_frame_adjust_volume(write_frame, spy->write_vol_adjustment);

	if (ast_test_flag(spy, CHANSPY_MIXAUDIO)) {
		ast_frame_slinear_sum(read_frame, write_frame);

		if (need_dup)
			result = ast_frdup(read_frame);
		else {
			result = read_frame;
			ast_frfree(write_frame);
		}
	} else {
		if (need_dup) {
			result = ast_frdup(read_frame);
			result->next = ast_frdup(write_frame);
		} else {
			result = read_frame;
			result->next = write_frame;
		}
	}

	return result;
}

static void *silence_generator_alloc(struct ast_channel *chan, void *data)
{
	/* just store the data pointer in the channel structure */
	return data;
}

static void silence_generator_release(struct ast_channel *chan, void *data)
{
	/* nothing to do */
}

static int silence_generator_generate(struct ast_channel *chan, void *data, int len, int samples)
{
	short buf[samples];
	int x;
	struct ast_frame frame = {
		.frametype = AST_FRAME_VOICE,
		.subclass = AST_FORMAT_SLINEAR,
		.data = buf,
		.samples = samples,
		.datalen = sizeof(buf),
	};

	for (x = 0; x < samples; x++)
		buf[x] = 0;

	if (ast_write(chan, &frame))
		return -1;

	return 0;
}

static struct ast_generator silence_generator = {
	.alloc = silence_generator_alloc,
	.release = silence_generator_release,
	.generate = silence_generator_generate,
};

struct ast_silence_generator {
	int old_write_format;
};

struct ast_silence_generator *ast_channel_start_silence_generator(struct ast_channel *chan)
{
	struct ast_silence_generator *state;

	if (!(state = ast_calloc(1, sizeof(*state)))) {
		return NULL;
	}

	state->old_write_format = chan->writeformat;

	if (ast_set_write_format(chan, AST_FORMAT_SLINEAR) < 0) {
		ast_log(LOG_ERROR, "Could not set write format to SLINEAR\n");
		free(state);
		return NULL;
	}

	ast_activate_generator(chan, &silence_generator, state);

	if (option_debug)
		ast_log(LOG_DEBUG, "Started silence generator on '%s'\n", chan->name);

	return state;
}

void ast_channel_stop_silence_generator(struct ast_channel *chan, struct ast_silence_generator *state)
{
	if (!state)
		return;

	ast_deactivate_generator(chan);

	if (option_debug)
		ast_log(LOG_DEBUG, "Stopped silence generator on '%s'\n", chan->name);

	if (ast_set_write_format(chan, state->old_write_format) < 0)
		ast_log(LOG_ERROR, "Could not return write format to its original state\n");

	free(state);
}


/*! \ brief Convert channel reloadreason (ENUM) to text string for manager event */
const char *channelreloadreason2txt(enum channelreloadreason reason)
{
	switch (reason) {
	case CHANNEL_MODULE_LOAD:
		return "LOAD (Channel module load)";

	case CHANNEL_MODULE_RELOAD:
		return "RELOAD (Channel module reload)";

	case CHANNEL_CLI_RELOAD:
		return "CLIRELOAD (Channel module reload by CLI command)";

	default:
		return "MANAGERRELOAD (Channel module reload by manager)";
	}
};