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sortix--sortix/sortix/sound.cpp
2011-08-23 21:02:15 +02:00

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1.6 KiB
C++

/******************************************************************************
COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.
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.h
Implements a simple sound system.
******************************************************************************/
#include "platform.h"
#include "sound.h"
namespace Sortix
{
namespace Sound
{
void Mute()
{
uint8_t TMP = (CPU::InPortB(0x61)) & 0xFC;
CPU::OutPortB(0x61, TMP);
}
void Play(nat Frequency)
{
//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(CPU::InterruptRegisters* R)
{
unsigned frequency = R->ebx;
if ( frequency == 0 ) { Mute(); } else { Play(frequency); }
}
}
}