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// license:BSD-3-Clause
// copyright-holders:Kevin Thacker
/***************************************************************************
Simple beeper sound driver
This is used for computers/systems which can only output a constant tone.
This tone can be turned on and off.
e.g. PCW and PCW16 computer systems
KT - 25-Jun-2000
****************************************************************************/
#include "emu.h"
#include "sound/beep.h"
#define BEEP_RATE (384000)
// device type definition
DEFINE_DEVICE_TYPE(BEEP, beep_device, "beep", "Beep")
beep_device::beep_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: device_t(mconfig, BEEP, tag, owner, clock)
, device_sound_interface(mconfig, *this)
, m_stream(nullptr)
, m_enable(0)
, m_frequency(clock)
{
}
//-------------------------------------------------
// device_start - device-specific startup
//-------------------------------------------------
void beep_device::device_start()
{
m_stream = stream_alloc(0, 1, BEEP_RATE);
m_enable = 0;
m_signal = 1.0;
// register for savestates
save_item(NAME(m_enable));
save_item(NAME(m_frequency));
save_item(NAME(m_incr));
save_item(NAME(m_signal));
}
//-------------------------------------------------
// sound_stream_update - handle a stream update
//-------------------------------------------------
void beep_device::sound_stream_update(sound_stream &stream, std::vector<read_stream_view> const &inputs, std::vector<write_stream_view> &outputs)
{
auto &buffer = outputs[0];
int16_t signal = m_signal;
int clock = 0, rate = BEEP_RATE / 2;
/* get progress through wave */
int incr = m_incr;
if (m_frequency > 0)
clock = m_frequency;
/* if we're not enabled, just fill with 0 */
if ( !m_enable || clock == 0 )
{
buffer.fill(0);
return;
}
/* fill in the sample */
for (int sampindex = 0; sampindex < buffer.samples(); sampindex++)
{
buffer.put(sampindex, signal);
incr -= clock;
while( incr < 0 )
{
incr += rate;
signal = -signal;
}
}
/* store progress through wave */
m_incr = incr;
m_signal = signal;
}
//-------------------------------------------------
// changing state to on from off will restart tone
//-------------------------------------------------
WRITE_LINE_MEMBER(beep_device::set_state)
{
/* only update if new state is not the same as old state */
int on = (state) ? 1 : 0;
if (m_enable == on)
return;
m_stream->update();
m_enable = on;
/* restart wave from beginning */
m_incr = 0;
m_signal = 1.0;
}
//-------------------------------------------------
// setting new frequency starts from beginning
//-------------------------------------------------
void beep_device::set_clock(uint32_t frequency)
{
if (m_frequency == frequency)
return;
m_stream->update();
m_frequency = frequency;
m_signal = 1.0;
m_incr = 0;
}
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