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// license: GPL-2.0+
// copyright-holders: Dirk Best
/***************************************************************************
National Semiconductor MM5837
Digital Noise Source
___ ___
VDD 1 |* u | 5 N/C
VGG 2 | | 6 N/C
OUTPUT 3 | | 7 N/C
VSS 4 |_______| 8 N/C
***************************************************************************/
#ifndef MAME_SOUND_MM5837_H
#define MAME_SOUND_MM5837_H
#pragma once
//**************************************************************************
// TYPE DEFINITIONS
//**************************************************************************
class mm5837_device : public device_t
{
public:
// construction/destruction
mm5837_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock = 0);
// configuration
void set_vdd_voltage(int voltage) { m_vdd = voltage; }
auto output_callback() { return m_output_cb.bind(); }
protected:
// device-level overrides
virtual void device_start() override;
virtual void device_reset() override;
virtual void device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr) override;
private:
// taken from the book 'mims circuit scrapbook, vol. 1'
// this is the frequency the chip runs at when given a vdd voltage of -0 to -15
static constexpr int m_frequency[16] = { 0, 0, 0, 0, 0, 0, 1, 2267, 8731, 16382, 23531, 32564, 38347, 40010, 37800, 33173 };
// callbacks
devcb_write_line m_output_cb;
// voltage (as positive number)
int m_vdd;
// output timer
emu_timer *m_timer;
// state
uint32_t m_shift;
};
// device type definition
DECLARE_DEVICE_TYPE(MM5837, mm5837_device)
#endif // MAME_SOUND_MM5837_H
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