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// license:BSD-3-Clause
// copyright-holders:Nigel Barnes
/***************************************************************************

    Peaksoft Prestel Module

    Also known as the New Era Interface from Peaksoft/Harry Whitehouse, which
    includes a through port for DOS cartridges.

    TODO:
    - add throughport, not known how CTS/SCS lines are switched between slots.

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

#include "emu.h"
#include "dragon_serial.h"
#include "machine/6850acia.h"
#include "machine/clock.h"
#include "bus/rs232/rs232.h"


namespace {

class dragon_serial_device : public device_t, public device_cococart_interface
{
public:
	dragon_serial_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
		: device_t(mconfig, DRAGON_SERIAL, tag, owner, clock)
		, device_cococart_interface(mconfig, *this )
		, m_eprom(*this, "eprom")
		, m_acia(*this, "acia")
	{
	}

protected:
	// device_t overrides
	virtual void device_start() override { }
	virtual u8 *get_cart_base() override { return m_eprom->base(); }
	virtual memory_region *get_cart_memregion() override { return m_eprom; }

	// optional information overrides
	virtual void device_add_mconfig(machine_config &config) override ATTR_COLD;
	virtual const tiny_rom_entry *device_rom_region() const override ATTR_COLD;

	virtual u8 cts_read(offs_t offset) override;
	virtual u8 scs_read(offs_t offset) override;
	virtual void scs_write(offs_t offset, u8 data) override;

private:
	required_memory_region m_eprom;
	required_device<acia6850_device> m_acia;
};


//-------------------------------------------------
//  ROM( dragon_serial )
//-------------------------------------------------

ROM_START(dragon_serial)
	ROM_REGION(0x2000, "eprom", 0)
	ROM_LOAD("comron_peaksoft.rom", 0x0000, 0x2000, CRC(9d18cf46) SHA1(14124dfb4bd78d1907e80d779cd7f3bae30564c9))
ROM_END

const tiny_rom_entry *dragon_serial_device::device_rom_region() const
{
	return ROM_NAME( dragon_serial );
}


//-------------------------------------------------
//  device_add_mconfig - add device configuration
//-------------------------------------------------

void dragon_serial_device::device_add_mconfig(machine_config &config)
{
	ACIA6850(config, m_acia, 0);
	m_acia->txd_handler().set("rs232", FUNC(rs232_port_device::write_txd));
	m_acia->rts_handler().set("rs232", FUNC(rs232_port_device::write_rts));
	m_acia->irq_handler().set([this](int state) { set_line_value(line::NMI, state); });

	clock_device &rx_clock(CLOCK(config, "rx_clock", 2.4576_MHz_XTAL / 32));  // 1200 baud
	rx_clock.signal_handler().set(m_acia, FUNC(acia6850_device::write_rxc));

	clock_device &tx_clock(CLOCK(config, "tx_clock", 2.4576_MHz_XTAL / 512)); // 75 baud
	tx_clock.signal_handler().set(m_acia, FUNC(acia6850_device::write_txc));

	rs232_port_device &rs232(RS232_PORT(config, "rs232", default_rs232_devices, "null_modem"));
	rs232.rxd_handler().set(m_acia, FUNC(acia6850_device::write_rxd));
	rs232.cts_handler().set(m_acia, FUNC(acia6850_device::write_cts));
	rs232.dcd_handler().set(m_acia, FUNC(acia6850_device::write_dcd)).invert();
}


//-------------------------------------------------
//  cts_read
//-------------------------------------------------

u8 dragon_serial_device::cts_read(offs_t offset)
{
	return m_eprom->base()[offset & 0x1fff];
}

//-------------------------------------------------
//  scs_read
//-------------------------------------------------

u8 dragon_serial_device::scs_read(offs_t offset)
{
	uint8_t result = 0x00;

	switch (offset)
	{
	case 0x14: case 0x15:
		result = m_acia->read(offset & 1);
		break;
	}

	return result;
}

//-------------------------------------------------
//  scs_write
//-------------------------------------------------

void dragon_serial_device::scs_write(offs_t offset, u8 data)
{
	switch (offset)
	{
	case 0x14: case 0x15:
		m_acia->write(offset & 1, data);
		break;
	}
}

} // anonymous namespace


DEFINE_DEVICE_TYPE_PRIVATE(DRAGON_SERIAL, device_cococart_interface, dragon_serial_device, "dragon_serial", "Dragon Peaksoft Prestel Module")