/*******************************************************************************

    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.

    This file is part of Sortix.

    Sortix 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 3 of the License, or (at your option) any later
    version.

    Sortix 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
    Sortix. If not, see <http://www.gnu.org/licenses/>.

    sound.cpp
    Implements a simple sound system.

*******************************************************************************/

#include <sortix/kernel/platform.h>
#include <sortix/kernel/kthread.h>
#include <sortix/kernel/syscall.h>

#include "cpu.h"
#include "sound.h"

namespace Sortix
{
	namespace Sound
	{
		kthread_mutex_t soundlock;

		void Mute()
		{
			ScopedLock lock(&soundlock);
			uint8_t TMP = (CPU::InPortB(0x61)) & 0xFC;

			CPU::OutPortB(0x61, TMP);
		}

		void Play(unsigned Frequency)
		{
			ScopedLock lock(&soundlock);
			//Set the PIT to the desired frequency
			uint32_t Div = 1193180 / Frequency;
			CPU::OutPortB(0x43, 0xB6);
			CPU::OutPortB(0x42, (uint8_t) (Div) );
			CPU::OutPortB(0x42, (uint8_t) (Div >> 8));

			// And play the sound using the PC speaker
			uint8_t TMP = CPU::InPortB(0x61);

			if ( TMP != (TMP | 3) )
			{
				CPU::OutPortB(0x61, TMP | 3);
			}
		}

		void SysSetFrequency(unsigned frequency)
		{
			if ( frequency == 0 ) { Mute(); } else { Play(frequency); }
		}

		void Init()
		{
			soundlock = KTHREAD_MUTEX_INITIALIZER;
			Syscall::Register(SYSCALL_SET_FREQUENCY, (void*) SysSetFrequency);
		}
	}
}