Volume.hxx

/*
 * Copyright 2003-2019 The Music Player Daemon Project
 * http://www.musicpd.org
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#ifndef MPD_VOLUME_HXX
#define MPD_VOLUME_HXX

#include "util/Compiler.h"

class MultipleOutputs;
class BufferedOutputStream;

void
InvalidateHardwareVolume() noexcept;

gcc_pure
int
volume_level_get(const MultipleOutputs &outputs) noexcept;

bool
volume_level_change(MultipleOutputs &outputs, unsigned volume);

bool
read_sw_volume_state(const char *line, MultipleOutputs &outputs);

void
save_sw_volume_state(BufferedOutputStream &os);

/**
 * Generates a hash number for the current state of the software
 * volume control.  This is used by timer_save_state_file() to
 * determine whether the state has changed and the state file should
 * be saved.
 */
gcc_pure
unsigned
sw_volume_state_get_hash() noexcept;

#endif